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  Subjects -> CHEMISTRY (Total: 848 journals)
    - ANALYTICAL CHEMISTRY (47 journals)
    - CHEMISTRY (603 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (45 journals)
    - PHYSICAL CHEMISTRY (65 journals)

CHEMISTRY (603 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 6)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 25)
ACS Catalysis     Full-text available via subscription   (Followers: 29)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 24)
ACS Macro Letters     Full-text available via subscription   (Followers: 22)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 36)
ACS Nano     Full-text available via subscription   (Followers: 195)
ACS Photonics     Full-text available via subscription   (Followers: 7)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 20)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 1)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 6)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 4)
Advanced Functional Materials     Hybrid Journal   (Followers: 45)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 52)
Advances in Chemical Science     Open Access   (Followers: 11)
Advances in Chemistry     Open Access   (Followers: 11)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 17)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Enzyme Research     Open Access   (Followers: 8)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 12)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 16)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 39)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 17)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 7)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Alchemy : Jurnal Penelitian Kimia     Open Access  
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 65)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 24)
American Journal of Plant Physiology     Open Access   (Followers: 12)
American Mineralogist     Full-text available via subscription   (Followers: 8)
Anadolu University Journal of Science and Technology     Open Access  
Analyst     Full-text available via subscription   (Followers: 42)
Angewandte Chemie     Hybrid Journal   (Followers: 143)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 193)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 7)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 6)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 23)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 3)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 6)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 9)
Biochemistry     Full-text available via subscription   (Followers: 253)
Biochemistry Insights     Open Access   (Followers: 5)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 3)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 17)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 114)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 100)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 1)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 26)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 2)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 8)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 64)
Catalysis for Sustainable Energy     Open Access   (Followers: 5)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 6)
Cellulose     Hybrid Journal   (Followers: 5)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 7)
Chemical and Engineering News     Free   (Followers: 11)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 71)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 21)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 18)
Chemical Reviews     Full-text available via subscription   (Followers: 155)
Chemical Science     Open Access   (Followers: 19)
Chemical Technology     Open Access   (Followers: 14)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 53)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 7)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 4)
Chemistry - A European Journal     Hybrid Journal   (Followers: 126)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 14)
Chemistry and Materials Research     Open Access   (Followers: 15)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 4)
Chemistry in Education     Open Access   (Followers: 3)
Chemistry International     Hybrid Journal   (Followers: 1)
Chemistry Letters     Full-text available via subscription   (Followers: 45)
Chemistry of Materials     Full-text available via subscription   (Followers: 163)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 8)
ChemPlusChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography Research International     Open Access   (Followers: 6)
Clay Minerals     Full-text available via subscription   (Followers: 8)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 3)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Composite Interfaces     Hybrid Journal   (Followers: 5)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 1)
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 2)
CrystEngComm     Full-text available via subscription   (Followers: 10)
Current Catalysis     Hybrid Journal   (Followers: 1)
Current Metabolomics     Hybrid Journal   (Followers: 3)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 8)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 15)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 46)
Dalton Transactions     Full-text available via subscription   (Followers: 18)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 11)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 3)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 2)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
EDUSAINS     Open Access  
Elements     Full-text available via subscription   (Followers: 1)
Environmental Chemistry     Hybrid Journal   (Followers: 5)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 2)

        1 2 3 4 | Last

Journal Cover Advanced Functional Materials
  [SJR: 5.21]   [H-I: 203]   [45 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1616-301X - ISSN (Online) 1616-3028
   Published by John Wiley and Sons Homepage  [1605 journals]
  • Near-Stoichiometric Bulk Graphane from Halogenated Graphenes (X = Cl/Br/I)
           by the Birch Reduction for High Density Energy Storage
    • Authors: Alex Yong Sheng Eng; Zdeněk Sofer, Daniel Bouša, David Sedmidubský, Štěpán Huber, Martin Pumera
      Abstract: Hydrogen is a clean fuel with high specific energy and its handling and storage are important toward fuel cell research. Particularly, high-density hydrogen storage is crucial for the viability of future hydrogen-powered devices. This leads to the search for suitable methods; one such option is chemical storage in light materials with large surface areas, such as graphene. Here, the bulk production of graphane by Birch reduction of halogenated (Cl/Br/I) graphene precursors is reported as a potentially scalable procedure. Prior treatment with strong hydrohalic acids is used to remove oxygen-groups and to substitute these with halogens, resulting in effective hydrogenation. An unprecedented level of hydrogen storage is obtained from the iodinated-graphene starting material at 7.44 wt%, far above the U.S. Department of Energy's 2020 system target of 5.5 wt% and close to its ultimate 7.5 wt% goal. As the stored hydrogen is chemisorbed on the graphane scaffold it is stable at both room temperature and on atmospheric exposure, where neither temperature control nor pressure regulation is required. Hydrogen may then be desorbed at elevated temperatures above 400 °C.Bulk graphane is prepared from halogenated graphene precursors (X = Cl/Br/I), giving levels of stored hydrogen in the material close to the theoretical limit. The graphane produced is stable in air and hydrogen can be subsequently desorbed at elevated temperature. High density hydrogen storage makes graphane a possible option for future hydrogen-powered devices.
      PubDate: 2017-02-15T07:20:59.263004-05:
      DOI: 10.1002/adfm.201605797
       
  • Near-Infrared Laser-Triggered Nitric Oxide Nanogenerators for the Reversal
           of Multidrug Resistance in Cancer
    • Authors: Ranran Guo; Ye Tian, Yajun Wang, Wuli Yang
      Abstract: The potential therapeutic implications of nitric oxide (NO) for diverse diseases have been under consideration for years; however, the development of precisely controllable NO generation system with potential for clinical application has remained elusive. Herein, intelligent near-infrared (NIR) laser-triggered NO nanogenerators for the treatment of multidrug-resistant (MDR) cancer are fabricated by integrating photothermal agents and heat-sensitive NO donors into a single nanoparticle. Such nanogenerators can absorb 808 nm NIR photons and convert them into ample heat to trigger NO release. The generated NO molecules are demonstrated to successfully achieve multidrug-resistance reversal by inhibiting the expression of P-glycol protein. Consequently, the intracellular accumulation of doxorubicin is effectively increased, resulting in high toxicity to MDR cancer cells in vitro. By virtue of surface modification with targeting ligands, these nanoparticles are able to selectively accumulate in tumor tissue. The therapeutic effects of the nanogenerators are validated in a humanized MDR cancer model. The in vivo experiment indicates that the nanoparticles possess excellent tumor suppression functionality with few side effects upon NIR laser exposure. Therefore, this novel photothermal conversion-based NO-releasing platform is expected to be a potential alternative to clinical MDR cancer treatment and may provide insights with regard to other NO-relevant medical treatments.Near-infrared laser-triggered nitric oxide (NO) nanogenerators are prepared by combining photothermal agents with heat-sensitive NO donors. NO release is realized via the conversion of light to heat, and excellent controllability is achieved in aqueous solution and multidrug-resistant (MDR) cancer cells under near-infrared laser irradiation. Furthermore, the proposed NO-releasing platform can successfully induce multidrug-resistance reversal and tumor inhibition in a humanized MDR cancer model.
      PubDate: 2017-02-15T07:20:38.303178-05:
      DOI: 10.1002/adfm.201606398
       
  • Biocompatible D–A Semiconducting Polymer Nanoparticle with
           Light-Harvesting Unit for Highly Effective Photoacoustic Imaging Guided
           Photothermal Therapy
    • Authors: Jinfeng Zhang; Caixia Yang, Rui Zhang, Rui Chen, Zhenyu Zhang, Wenjun Zhang, Shih-Hao Peng, Xiaoyuan Chen, Gang Liu, Chain-Shu Hsu, Chun-Sing Lee
      Abstract: The development of nanotheranostic agents that integrate diagnosis and therapy for effective personalized precision medicine has obtained tremendous attention in the past few decades. In this report, biocompatible electron donor–acceptor conjugated semiconducting polymer nanoparticles (PPor-PEG NPs) with light-harvesting unit is prepared and developed for highly effective photoacoustic imaging guided photothermal therapy. To the best of our knowledge, it is the first time that the concept of light-harvesting unit is exploited for enhancing the photoacoustic signal and photothermal energy conversion in polymer-based theranostic agent. Combined with additional merits including donor–acceptor pair to favor electron transfer and fluorescence quenching effect after NP formation, the photothermal conversion efficiency of the PPor-PEG NPs is determined to be 62.3%, which is the highest value among reported polymer NPs. Moreover, the as-prepared PPor-PEG NP not only exhibits a remarkable cell-killing ability but also achieves 100% tumor elimination, demonstrating its excellent photothermal therapeutic efficacy. Finally, the as-prepared water-dispersible PPor-PEG NPs show good biocompatibility and biosafety, making them a promising candidate for future clinical applications in cancer theranostics.A water-dispersible and biocompatible D–A semiconducting polymer nanoparticle (PPor-PEG NP) with light-harvesting unit is successfully developed for highly effective photoacoustic imaging guided photothermal therapy. The photothermal conversion efficiency of the PPor-PEG NPs is determined to be as high as 62.3% for achieving 100% tumor elimination.
      PubDate: 2017-02-15T07:16:00.149864-05:
      DOI: 10.1002/adfm.201605094
       
  • A Lyotropic Liquid-Crystal-Based Assembly Avenue toward Highly Oriented
           Vanadium Pentoxide/Graphene Films for Flexible Energy Storage
    • Authors: Haiqing Liu; Yanping Tang, Chi Wang, Zhixiao Xu, Chongqing Yang, Tao Huang, Fan Zhang, Dongqing Wu, Xinliang Feng
      Abstract: A novel lyotropic liquid-crystal (LC) based assembly strategy is developed for the first time, to fabricate composite films of vanadium pentoxide (V2O5) nanobelts and graphene oxide (GO) sheets, with highly oriented layered structures. It is found that similar lamellar LC phases can be simply established by V2O5 nanobelts alone or by a mixture of V2O5 nanobelts and GO nanosheets in their aqueous dispersions. More importantly, the LC phases can be retained with any proportion of V2O5 nanobelts and GO, which allows facile optimization of the ratio of each component in the resulting films. Named VrGO, composite films manifest high electrical conductivity, good mechanical stability, and excellent flexibility, which allow them to be utilized as high performance electrodes in flexible energy storage devices. As demonstrated in this work, the VrGO films containing 67 wt% V2O5 exhibit excellent capacitance of 166 F g−1 at 10 A g−1; superior to those of the previously reported composites of V2O5 and nanocarbon. Moreover, the VrGO film in flexible lithium ion batteries delivers a high capacity of 215 mAh g−1 at 0.1 A g−1; comparable to the best V2O5 based cathode materials.A novel lyotropic liquid-crystal-based assembly strategy is developed for the first time to fabricate composite films of vanadium pentoxide nanobelts and graphene oxide sheets with highly oriented layered structures. The resulting films manifest high electrical conductivity, good mechanical stability, and excellent flexibility, which allow them to be utilized as high performance electrodes in flexible energy storage devices.
      PubDate: 2017-02-15T07:15:40.198533-05:
      DOI: 10.1002/adfm.201606269
       
  • High Current Density Electrical Breakdown of TiS3 Nanoribbon-Based
           Field-Effect Transistors
    • Authors: Aday J. Molina-Mendoza; Joshua O. Island, Wendel S. Paz, Jose Manuel Clamagirand, Jose Ramón Ares, Eduardo Flores, Fabrice Leardini, Carlos Sánchez, Nicolás Agraït, Gabino Rubio-Bollinger, Herre S. J. van der Zant, Isabel J. Ferrer, J. J. Palacios, Andres Castellanos-Gomez
      Abstract: The high field transport characteristics of nanostructured transistors based on layered materials are not only important from a device physics perspective but also for possible applications in next generation electronics. With the growing promise of layered materials as replacements to conventional silicon technology, the high current density properties of the layered material titanium trisulfide (TiS3) are studied here. The high breakdown current densities of up to 1.7 × 106 A cm−2 are observed in TiS3 nanoribbon-based field-effect transistors, which are among the highest found in semiconducting nanomaterials. Investigating the mechanisms responsible for current breakdown, a thermogravimetric analysis of bulk TiS3 is performed and the results with density functional theory and kinetic Monte Carlo calculations are compared. In conclusion, the oxidation of TiS3 and subsequent desorption of sulfur atoms play an important role in the electrical breakdown of the material in ambient conditions. The results show that TiS3 is an attractive material for high power applications and lend insight into the thermal and defect activated mechanisms responsible for electrical breakdown in nanostructured devices.TiS3 nanoribbons-based field-effect transistors are found to stand one of the highest current densities among nanostructured materials. The mechanisms that lead to the nanodevice breakdown are investigated in the bulk material by thermogravimetric analysis measurements and by density functional theory calculations together with kinetic Monte Carlo simulations, and are found to be due to oxygen-mediated sulfur desorption.
      PubDate: 2017-02-15T07:15:34.065794-05:
      DOI: 10.1002/adfm.201605647
       
  • Lithography: Electrowetting-Induced Morphological Evolution of
           Metal-Organic Inverse Opals toward a Water-Lithography Approach (Adv.
           Funct. Mater. 7/2017)
    • Authors: Junchao Liu; Lun Wan, Manbo Zhang, Kejian Jiang, Kai Song, Jingxia Wang, Tomiki Ikeda, Lei Jiang
      Abstract: The cover describes a unique morphology evolution of interconnected inverse opals during electrowetting. The interconnected pores are transformed to the separate hollow spheres of metal-organic inverse opals during the process. This phenomenon can serve as a novel water-lithography approach for the fabrication of colloidal crystal patterns as described by Jingxia Wang and co-workers in article number 1605221.
      PubDate: 2017-02-15T05:45:02.041142-05:
      DOI: 10.1002/adfm.201770043
       
  • Cathode Materials: Atomic Insights into the Enhanced Surface Stability in
           High Voltage Cathode Materials by Ultrathin Coating (Adv. Funct. Mater.
           7/2017)
    • Authors: Xin Fang; Feng Lin, Dennis Nordlund, Matthew Mecklenburg, Mingyuan Ge, Jiepeng Rong, Anyi Zhang, Chenfei Shen, Yihang Liu, Yu Cao, Marca M. Doeff, Chongwu Zhou
      Abstract: Atomic layer deposition of Al2O3 is employed as ultrathin coating on LiNi0.5Mn1.5O4, a high voltage cathode in Li-ion batteries. X-ray absorption spectroscopy and scanning transmission electron microscopy electron energy loss spectroscopy show that the coating suppresses Mn2+ formation on the surface and decelerates impedance buildup. The detailed analysis by Chongwu Zhou and co-workers is shown in article number 1602873.
      PubDate: 2017-02-15T05:45:00.380501-05:
      DOI: 10.1002/adfm.201770042
       
  • Masthead: (Adv. Funct. Mater. 7/2017)
    • PubDate: 2017-02-15T05:44:58.990315-05:
      DOI: 10.1002/adfm.201770040
       
  • Ferrimagnetic Fibers: Toroidal Protein Adaptor Assembles Ferrimagnetic
           Nanoparticle Fibers with Constructive Magnetic Coupling (Adv. Funct.
           Mater. 7/2017)
    • Authors: Tuan Anh Pham; Andreas Schreiber, Stefan M. Schiller, Helmut Cölfen
      Abstract: In article number 1604532 Stefan M. Schiller, Helmut Cölfen, and co-workers apply the toroidal protein Hcp1 to connect cobalt ferrite nanoparticles (NPs). The cover illustrates the directed molecular assembly and ferrimagnetic coupling of NPs into biohybrid nanofibers. The fibers exhibit enhanced saturation (+28%) and remanence magnetization (+38%) and a coercive field (+12%) comparable to high-end Nd2Fe14B bulk magnets at 2 K.
      PubDate: 2017-02-15T05:44:58.934271-05:
      DOI: 10.1002/adfm.201770039
       
  • Metal-Free Catalysis: Unraveling Surface Basicity and Bulk Morphology
           Relationship on Covalent Triazine Frameworks with Unique Catalytic and Gas
           Adsorption Properties (Adv. Funct. Mater. 7/2017)
    • Authors: Giulia Tuci; Moritz Pilaski, Housseinou Ba, Andrea Rossin, Lapo Luconi, Stefano Caporali, Cuong Pham-Huu, Regina Palkovits, Giuliano Giambastiani
      Abstract: Porous, cross-linked organic architectures containing N-functionalities excellently catalyze the steam- and oxygenfree ethylbenzene dehydrogenation into styrene. Cuong Pham-Huu, Regina Palkovits, Giuliano Giambastiani, and co-workers analyze the catalysts thermal stability and chemico-physical properties in article number 1605672. Chemically accessible surface basicity is shown to control the catalyst deactivation caused by the generation of coke deposits.
      PubDate: 2017-02-15T05:44:56.510404-05:
      DOI: 10.1002/adfm.201770038
       
  • Contents: (Adv. Funct. Mater. 7/2017)
    • PubDate: 2017-02-15T05:44:55.951153-05:
      DOI: 10.1002/adfm.201770041
       
  • Ultrathin Nickel–Cobalt Phosphate 2D Nanosheets for Electrochemical
           Energy Storage under Aqueous/Solid-State Electrolyte
    • Authors: Bing Li; Peng Gu, Yongcheng Feng, Guangxun Zhang, Kesheng Huang, Huaiguo Xue, Huan Pang
      Abstract: 2D materials are ideal for constructing flexible electrochemical energy storage devices due to their great advantages of flexibility, thinness, and transparency. Here, a simple one-step hydrothermal process is proposed for the synthesis of nickel–cobalt phosphate 2D nanosheets, and the structural influence on the pseudocapacitive performance of the obtained nickel–cobalt phosphate is investigated via electrochemical measurement. It is found that the ultrathin nickel–cobalt phosphate 2D nanosheets with an Ni/Co ratio of 4:5 show the best electrochemical performance for energy storage, and the maximum specific capacitance up to 1132.5 F g−1. More importantly, an aqueous and solid-state flexible electrochemical energy storage device has been assembled. The aqueous device shows a high energy density of 32.5 Wh kg−1 at a power density of 0.6 kW kg−1, and the solid-state device shows a high energy density of 35.8 Wh kg−1 at a power density of 0.7 kW kg−1. These excellent performances confirm that the nickel–cobalt phosphate 2D nanosheets are promising materials for applications in electrochemical energy storage devices.Nickel–cobalt phosphate 2D ultrathin nanosheets are synthesized by a one-step hydrothermal process. Several reaction conditions are changed to explore the impact of the materials. The structural influence on the pseudocapacitive performance of the obtained sample is investigated via electrochemical measurement. It is found that the sample with an Ni/Co ratio of 4:5 shows the best electrochemical energy storage.
      PubDate: 2017-02-15T03:40:37.7745-05:00
      DOI: 10.1002/adfm.201605784
       
  • Highly Efficient Three Primary Color Organic Single-Crystal Light-Emitting
           Devices with Balanced Carrier Injection and Transport
    • Authors: Ran Ding; Jing Feng, Feng-Xi Dong, Wei Zhou, Yang Liu, Xu-Lin Zhang, Xue-Peng Wang, Hong-Hua Fang, Bin Xu, Xian-Bin Li, Hai-Yu Wang, Shu Hotta, Hong-Bo Sun
      Abstract: Organic single crystals have a great potential in the field of organic optoelectronics because of their advantages of high carrier mobility and high thermal stability. However, the application of the organic single crystals in light-emitting devices (OLEDs) has been limited by single-layered structure with unbalanced carrier injection and transport. Here, fabrication of a multilayered-structure crystal-based OLED constitutes a major step toward balanced carrier injection and transport by introducing an anodic buffer layer and electron transport layer into the device structure. Three primary color single-crystal-based OLEDs based on the multilayered structure and molecular doping exhibit a maximum luminance and current efficiency of 820 cd cm−2 and 0.9 cd A−1, respectively, which are the highest performance to date for organic single-crystal-based OLEDs. This work paves the way toward high-performance organic optoelectronic devices based on the organic single crystals.Efficient and bright organic single-crystal-based organic light-emitting devices (OLEDs) are achieved by the multilayered structure to improve carrier injection and transport. Three primary colors' OLEDs based on the multilayered structure and molecular doping exhibit a maximum luminance and current efficiency of 820 cd cm−2 and 0.9 cd A−1, respectively, which are the highest performance to date for the organic single-crystal-based OLEDs.
      PubDate: 2017-02-15T03:35:33.988828-05:
      DOI: 10.1002/adfm.201604659
       
  • Nanoengineering Hybrid Supramolecular Multilayered Biomaterials Using
           Polysaccharides and Self-Assembling Peptide Amphiphiles
    • Authors: João Borges; Maria P. Sousa, Goksu Cinar, Sofia G. Caridade, Mustafa O. Guler, João F. Mano
      Abstract: Developing complex supramolecular biomaterials through highly dynamic and reversible noncovalent interactions has attracted great attention from the scientific community aiming key biomedical and biotechnological applications, including tissue engineering, regenerative medicine, or drug delivery. In this study, the authors report the fabrication of hybrid supramolecular multilayered biomaterials, comprising high-molecular-weight biopolymers and oppositely charged low-molecular-weight peptide amphiphiles (PAs), through combination of self-assembly and electrostatically driven layer-by-layer (LbL) assembly approach. Alginate, an anionic polysaccharide, is used to trigger the self-assembling capability of positively charged PA and formation of 1D nanofiber networks. The LbL technology is further used to fabricate supramolecular multilayered biomaterials by repeating the alternate deposition of both molecules. The fabrication process is monitored by quartz crystal microbalance, revealing that both materials can be successfully combined to conceive stable supramolecular systems. The morphological properties of the systems are studied by advanced microscopy techniques, revealing the nanostructured dimensions and 1D nanofibrous network of the assembly formed by the two molecules. Enhanced C2C12 cell adhesion, proliferation, and differentiation are observed on nanostructures having PA as outermost layer. Such supramolecular biomaterials demonstrate to be innovative matrices for cell culture and hold great potential to be used in the near future as promising biomimetic supramolecular nanoplatforms for practical applications.The fabrication of hybrid supramolecular nanostructured multilayered biomaterials, comprising high-molecular-weight alginate biopolymer and oppositely charged low-molecular-weight self-assembling peptide amphiphile molecule, is reported through the combination of self-assembly and electrostatically driven layer-by-layer assembly approach. Enhanced cell adhesion, proliferation, and differentiation are observed on supramolecular nanostructures having peptide amphiphile as the outermost layer, constituting promising bioinstructive matrices for biomedical and healthcare applications.
      PubDate: 2017-02-15T03:25:41.469845-05:
      DOI: 10.1002/adfm.201605122
       
  • 2D Organic–Inorganic Hybrid Thin Films for Flexible UV–Visible
           Photodetectors
    • Authors: Dhinesh Babu Velusamy; Md. Azimul Haque, Manas R. Parida, Fan Zhang, Tom Wu, Omar F. Mohammed, Husam N. Alshareef
      Abstract: Flexible 2D inorganic MoS2 and organic g-C3N4 hybrid thin film photodetectors with tunable composition and photodetection properties are developed using simple solution processing. The hybrid films fabricated on paper substrate show broadband photodetection suitable for both UV and visible light with good responsivity, detectivity, and reliable and rapid photoswitching characteristics comparable to monolayer devices. This excellent performance is retained even after the films are severely deformed at a bending radius of ≈2 mm for hundreds of cycles. The detailed charge transfer and separation processes at the interface between the 2D materials in the hybrid films are confirmed by femtosecond transient absorption spectroscopy with broadband capability.Flexible 2D inorganic MoS2 and organic g-C3N4 hybrid thin film photodetectors with tunable composition and photodetection properties have been developed. The 5:5 hybrid films show broadband photodetection suitable for both UV and visible light with good responsivity, detectivity, and rapid photoswitching characteristics. The charge transfer processes at the interface of hybrid films are confirmed by femtosecond transient absorption spectroscopy.
      PubDate: 2017-02-13T07:20:52.982203-05:
      DOI: 10.1002/adfm.201605554
       
  • Nano/Microrobots Meet Electrochemistry
    • Authors: James Guo Sheng Moo; Carmen C. Mayorga-Martinez, Hong Wang, Bahareh Khezri, Wei Zhe Teo, Martin Pumera
      Abstract: Artificial autonomous self-propelled nano and microrobots are an important part of contemporary technology. They are typically self-powered, taking chemical energy from their environment and converting it to motion. They can move in complex environments and channels, deliver cargo, perform nanosurgery, act as chemotaxis and perform sense-and-act actions. The electrochemistry is closely interwoven within this field. In the case of self-electrophoretically driven nano/microrobots, electrochemical mechanism has been the basis of power, which translates chemical energy to motion. Electrochemistry is also a major tool for the fabrication of these micro and nanodevices. Electrochemistry and electric fields can be used for the directing of nanorobots and for detection of their positions. Ultimately, nano and microrobots can dramatically improve performances of electrochemical sensors and biosensors, as well as of the energy generating devices. Here, all aspects in the fundamentals and applications of electrochemistry in the realm of nano- and microrobots are reviewed.The nexus between electrochemistry and nano/microrobots is closely interwoven. In this confluence, fabrication, powering, control and applications of these self-propelled devices are illustrated. Understanding these fundamentals will push new frontiers for the locomotion of nano/microrobots.
      PubDate: 2017-02-13T07:20:42.12489-05:0
      DOI: 10.1002/adfm.201604759
       
  • Achieving High-Performance Nondoped OLEDs with Extremely Small Efficiency
           Roll-Off by Combining Aggregation-Induced Emission and Thermally Activated
           Delayed Fluorescence
    • Authors: Jingjing Guo; Xiang-Long Li, Han Nie, Wenwen Luo, Shifeng Gan, Shimin Hu, Rongrong Hu, Anjun Qin, Zujin Zhao, Shi-Jian Su, Ben Zhong Tang
      Abstract: Luminescent materials with thermally activated delayed fluorescence (TADF) can harvest singlet and triplet excitons to afford high electroluminescence (EL) efficiencies for organic light-emitting diodes (OLEDs). However, TADF emitters generally have to be dispersed into host matrices to suppress emission quenching and/or exciton annihilation, and most doped OLEDs of TADF emitters encounter a thorny problem of swift efficiency roll-off as luminance increases. To address this issue, in this study, a new tailor-made luminogen (dibenzothiophene-benzoyl-9,9-dimethyl-9,10-dihydroacridine, DBT-BZ-DMAC) with an unsymmetrical structure is synthesized and investigated by crystallography, theoretical calculation, spectroscopies, etc. It shows aggregation-induced emission, prominent TADF, and interesting mechanoluminescence property. Doped OLEDs of DBT-BZ-DMAC show high peak current and external quantum efficiencies of up to 51.7 cd A−1 and 17.9%, respectively, but the efficiency roll-off is large at high luminance. High-performance nondoped OLED is also achieved with neat film of DBT-BZ-DMAC, providing excellent maxima EL efficiencies of 43.3 cd A−1 and 14.2%, negligible current efficiency roll-off of 0.46%, and external quantum efficiency roll-off approaching null from peak values to those at 1000 cd m−2. To the best of the authors' knowledge, this is one of the most efficient nondoped TADF OLEDs with small efficiency roll-off reported so far.A highly efficient nondoped organic light-emitting diode affording excellent maxima electroluminescence efficiencies of 43.3 cd A−1 and 14.2%, negligible current efficiency roll-off of 0.46%, and external quantum efficiency roll-off approaching null from peak values to those at 1000 cd m−2, is attained based on a robust luminogen featuring aggregation-induced emission and thermally activated delayed fluorescence.
      PubDate: 2017-02-10T02:32:52.905472-05:
      DOI: 10.1002/adfm.201606458
       
  • Scaling the Aspect Ratio of Nanoscale Closely Packed Silicon Vias by
           MacEtch: Kinetics of Carrier Generation and Mass Transport
    • Authors: Jeong Dong Kim; Parsian K. Mohseni, Karthik Balasundaram, Srikanth Ranganathan, Jayavel Pachamuthu, James J. Coleman, Xiuling Li
      Abstract: Metal-assisted chemical etching (MacEtch) has shown tremendous success as an anisotropic wet etching method to produce ultrahigh aspect ratio semiconductor nanowire arrays, where a metal mesh pattern serves as the catalyst. However, producing vertical via arrays using MacEtch, which requires a pattern of discrete metal disks as the catalyst, has often been challenging because of the detouring of individual catalyst disks off the vertical path while descending, especially at submicron scales. Here, the realization of ordered, vertical, and high aspect ratio silicon via arrays by MacEtch is reported, with diameters scaled from 900 all the way down to sub-100 nm. Systematic variation of the diameter and pitch of the metal catalyst pattern and the etching solution composition allows the extraction of a physical model that, for the first time, clearly reveals the roles of the two fundamental kinetic mechanisms in MacEtch, carrier generation and mass transport. Ordered submicron diameter silicon via arrays with record aspect ratio are produced, which can directly impact the through-silicon-via technology, high density storage, photonic crystal membrane, and other related applications.Ordered, vertical, and high aspect ratio submicron silicon via array is fabricated by metal-assisted chemical etching. The physical model extracted from systematic variation of catalyst pattern and etching solution reveals the roles of two fundamental kinetic mechanisms, carrier generation and mass transport. This potentially disruptive etching technology can impact the formation of through-silicon-vias and high density electronic and photonic devices.
      PubDate: 2017-02-10T02:32:48.272636-05:
      DOI: 10.1002/adfm.201605614
       
  • Unveiling a Key Intermediate in Solvent Vapor Postannealing to Enlarge
           Crystalline Domains of Organometal Halide Perovskite Films
    • Authors: Shuang Xiao; Yang Bai, Xiangyue Meng, Teng Zhang, Haining Chen, Xiaoli Zheng, Chen Hu, Yongquan Qu, Shihe Yang
      Abstract: Hybrid organic/inorganic perovskite solar cells (PSCs) have shown great potential in meeting the future challenges in energy and environment. Solvent-vapor-assisted posttreatment strategies are developed to improve the perovskite film quality for achieving higher efficiency. However, the intrinsic working mechanisms of these strategies have not been well understood yet. This study identifies an MA2Pb3I8(DMSO)2 intermediate phase formed during the annealing process of methylammonium lead triiodide in dimethyl sulfoxide (DMSO) atmosphere and located the reaction sites at perovskite grain boundaries by observing and rationalizing the growth of nanorods of the intermediate. This enables us to propose and validate an intermediate-assisted grain-coarsening model, which highlights the activation energy reduction for grain boundary migration. Leveraging this mechanism, this study uses MABr/DMSO mixed vapor to further enhance grain boundary migration kinetics and successfully obtain even larger grains, leading to an impressive improvement in power conversion efficiency (17.64%) relative to the pristine PSCs (15.13%). The revelation of grain boundary migration-assisted grain growth provides a guide for the future development of polycrystalline perovskite thin-film solar cells.MA2Pb3I8(DMSO)2 intermediate is identified and tracked during the methylammonium lead triiodide thin-film anneal process under dimethyl sulfoxide (DMSO) solvent vapor, which helps to reduce the activation energy of perovskite grain boundary migration. Leveraging this mechanism, an MABr/DMSO mix vapor anneal method is developed to further facillitate grain goundary migration to achieve 17.64% efficiency in NiO-based inverted perovskite solar cell.
      PubDate: 2017-02-10T02:26:10.252501-05:
      DOI: 10.1002/adfm.201604944
       
  • Readdressing of Magnetoelectric Effect in Bulk BiFeO3
    • Authors: Xin Xin Shi; Xiao Qiang Liu, Xiang Ming Chen
      Abstract: After decades of study, BiFeO3 is still the most promising single-phase multiferroic material due to its large polarization and high operating temperature, drawing much attention. As a typical type-I multiferroic material, the magnetoelectric coupling in BiFeO3 is deemed to be weak due to the different origins of its ferroelectricity and magnetism. Here, the magnetoelectric effect in bulk BiFeO3 is readdressed both theoretically and experimentally. Based on the Dzyaloshinsky–Moriya interaction scenario, the magnetoelectric effect in BiFeO3 is actually strong, with a coupling energy of about 1.25 meV and a magnetism-coupled parasitic polarization comparable to that of the type-II multiferroics. However, such strong magnetoelectric coupling also causes the cycloidal spin structure, which inhibits the observation of linear magnetoelectric coupling in bulk BiFeO3. To resolve this contradiction, Sm-substitution is utilized to suppress the magnetoelectric effect and unlocks the weak ferromagnetism. At an optimized composition, such a weak ferromagnetic state can be switched back to the cycloidal state by an electric field, thus realizing electrical control of the magnetism. It has been argued that field-controlled phase transition is a promising path to colossal magnetoelectric effect. It is of pioneering significance for further investigations down this road.The present readdressing of the magnetoelectric effect in bulk BiFeO3 reveals that the strong magnetoelectric coupling and weak ferromagnetism are actually incompatible. To resolve such a contradiction, an electric-field-induced phase transition from the weak ferromagnetic state to the cycloidal spin state is focused and the concomitant reduction of the magnetization has been observed.
      PubDate: 2017-02-10T02:25:51.979026-05:
      DOI: 10.1002/adfm.201604037
       
  • Efficient and Flexible Thin Film Amorphous Silicon Solar Cells on
           Nanotextured Polymer Substrate Using Sol–gel Based Nanoimprinting Method
           
    • Authors: Chi Zhang; Ye Song, Min Wang, Min Yin, Xufei Zhu, Li Tian, Hui Wang, Xiaoyuan Chen, Zhiyong Fan, Linfeng Lu, Dongdong Li
      Abstract: The mechanical flexibility of substrates and controllable nanostructures are two major considerations in designing high-performance, flexible thin-film solar cells. In this work, we proposed an approach to realize highly ordered metal oxide nanopatterns on polyimide (PI) substrate based on the sol-gel chemistry and soft thermal nanoimprinting lithography. Thin-film amorphous silicon (a-Si:H) solar cells were subsequently constructed on the patterned PI flexible substrates. The periodic nanopatterns delivered broadband-enhanced light absorption and quantum efficiency, as well as the eventual power conversion efficiency (PCE). The nanotextures also benefit for the device yield and mechanical flexibility, which experienced little efficiency drop even after 100,000 bending cycles. In addition, flexible, transparent nanocone films, obtained by a template process, were attached onto the patterned PI solar cells, serving as top anti-reflection layers. The PCE performance with these dual-interfacial patterns rose up to 8.17%, that is, it improved by 48.5% over the planar device. Although the work was conducted on a-Si:H material, our proposed scheme can be extended to a variety of active materials for different optoelectronic applications.High-performance thin-film amorphous silicon (a-Si:H) solar cells have been fabricated on polyimide (PI) foils with periodic metal oxide nanopatterns via nanoimprinting lithography. It is found that properly designed nanohole substrates can significantly improve film quality, robustness, flexibility, and device efficiency due to the reduced interface stress and broadband-enhanced light harvesting capability.
      PubDate: 2017-02-10T02:20:33.903433-05:
      DOI: 10.1002/adfm.201604720
       
  • Sandwich-Like Nanocomposite of CoNiO x /Reduced Graphene Oxide for
           Enhanced Electrocatalytic Water Oxidation
    • Authors: Ping Li; Hua Chun Zeng
      Abstract: The development of cost-effective and high-performance electrocatalysts for oxygen evolution reaction (OER) is essential for sustainable energy storage and conversion processes. This study reports a novel and facile approach to the hierarchical-structured sheet-on-sheet sandwich-like nanocomposite of CoNiOx/reduced graphene oxide as highly active electrocatalysts for water oxidation. Notably, the as-prepared composite can operate smoothly both in 0.1 and 1.0 m KOH alkaline media, displaying extremely low overpotentials, fast kinetics, and strong durability over long-term continuous electrolysis. Impressively, it is found that its catalytic activity can be further promoted by anodic conditioning owing to the in situ generation of electrocatalytic active species (i.e., metal hydroxide/(oxy)hydroxides) and the enriched oxygen deficiencies at the surface. The achieved ultrahigh performance is unmatched by most of the transition-metal/nonmetal-based catalysts reported so far, and even better than the state-of-the-art noble-metal catalysts, which can be attributed to its special well-defined physicochemical textural features including hierarchical architecture, large surface area, porous thin nanosheets constructed from CoNiOx nanoparticles (≈5 nm in size), and the incorporation of charge-conducting graphene. This work provides a promising strategy to develop earth-abundant advanced OER electrocatalysts to replace noble metals for a multitude of renewable energy technologies.A hierarchical-structured sheet-on-sheet sandwich-like nanocomposite based on CoNiOx and reduced graphene oxide is engineered and developed through a self-assembly procedure followed with heat treatment. The resulting nanocomposite exhibits advanced electrocatalytic activity and stability for water oxidation.
      PubDate: 2017-02-10T02:14:21.4745-05:00
      DOI: 10.1002/adfm.201606325
       
  • High-Performance Oxygen Reduction Electrocatalyst Derived from
           Polydopamine and Cobalt Supported on Carbon Nanotubes for Metal–Air
           Batteries
    • Authors: Yiling Liu; Fengjiao Chen, Wen Ye, Min Zeng, Na Han, Feipeng Zhao, Xinxia Wang, Yanguang Li
      Abstract: The development of nonprecious metal-based electrocatalysts for the oxygen reduction reaction holds the decisive key to many energy conversion devices. Among several potential candidates, transition metal and nitrogen co-doped carbonaceous materials are the most promising, yet their activity and stability are still insufficient to meet the needs of practical applications. In this study, a core–shell hybrid electrocatalyst is developed via the self-polymerization of dopamine and cobalt on carbon nanotubes (CNTs), followed by high-temperature pyrolysis. The polymer-derived carbonaceous shell contains abundant structural defects and facilitates the formation of CoN/C active sites, whereas the graphitic carbon nanotube core provides high electrical conductivity and corrosion resistance. These two components separately fulfill different functionalities, and jointly afford the catalyst with excellent electrochemical performance. In 1 m KOH, CoN/CNT exhibits a positive half-wave potential of ≈0.91 V, low peroxide yield of
      PubDate: 2017-02-09T04:17:29.339858-05:
      DOI: 10.1002/adfm.201606034
       
  • Oil-Impregnated Nanoporous Oxide Layer for Corrosion Protection with
           Self-Healing
    • Authors: Junghoon Lee; Sangwoo Shin, Youhua Jiang, Chanyoung Jeong, Howard A. Stone, Chang-Hwan Choi
      Abstract: The major drawback of current passivation techniques for preventing corrosion is the lack of ability to withstand any external damages or local defects. In this study, oil-impregnated nanoporous anodic aluminum oxide (AAO) layers are investigated to overcome such limitations and thus advance corrosion protection. By completely filling hydrophobized nanopores with oil via a solvent exchange method, a highly water-repellent surface that prevents the penetration of corrosive media into the AAO layer and hence the corrosion of aluminum is achieved. The impregnation of oil into the hydrophobic nanoporous AAO layer enhances the corrosion resistance of an AAO layer by two and four orders of magnitude compared to that of a hydrophobic (i.e., air-entrained) and a bare (hydrophilic) AAO, respectively. In the presence of local defects, the oil impregnated within the hydrophobic nanoporous AAO layer naturally permeates into the defects and ultimately inhibits the exposure of the aluminum surface to corrosive media. Whereas the corrosion current density of the air-entrained hydrophobic AAO layer increases by more than 30 times after cracks, that of the oil-impregnated AAO layer increases by no more than 4 times, showing superior anticorrosion property even after there are cracks, owing to the effective self-healing capability.An oil-impregnated nanoporous anodic aluminum oxide (AAO) layer is fabricated by completely filling the Teflon-coated hydrophobic nanopores with perfluorinated oil via a solvent exchange method. The oil-impregnated nanoporous AAO, having high water repellency, prevents the penetration of corrosive media into the AAO layer and shows superior corrosion resistance and damage tolerance for corrosion with unique self-healing capability.
      PubDate: 2017-02-08T07:55:43.17935-05:0
      DOI: 10.1002/adfm.201606040
       
  • Cellulose Nanocrystal Inks for 3D Printing of Textured Cellular
           Architectures
    • Authors: Gilberto Siqueira; Dimitri Kokkinis, Rafael Libanori, Michael K. Hausmann, Amelia Sydney Gladman, Antonia Neels, Philippe Tingaut, Tanja Zimmermann, Jennifer A. Lewis, André R. Studart
      Abstract: 3D printing of renewable building blocks like cellulose nanocrystals offers an attractive pathway for fabricating sustainable structures. Here, viscoelastic inks composed of anisotropic cellulose nanocrystals (CNC) that enable patterning of 3D objects by direct ink writing are designed and formulated. These concentrated inks are composed of CNC particles suspended in either water or a photopolymerizable monomer solution. The shear-induced alignment of these anisotropic building blocks during printing is quantified by atomic force microscopy, polarized light microscopy, and 2D wide-angle X-ray scattering measurements. Akin to the microreinforcing effect in plant cell walls, the alignment of CNC particles during direct writing yields textured composites with enhanced stiffness along the printing direction. The observations serve as an important step forward toward the development of sustainable materials for 3D printing of cellular architectures with tailored mechanical properties.Aqueous and polymer-based inks with high cellulose nanocrystal (CNC) loading are developed for 3D printing of textured cellular architectures. Alignment of CNC particles within the 3D printed filaments leads to enhanced mechanical properties along the printing direction, akin to wood and other biological composites.
      PubDate: 2017-02-07T07:36:04.759956-05:
      DOI: 10.1002/adfm.201604619
       
  • Naphthothiadiazole-Based Near-Infrared Emitter with a Photoluminescence
           Quantum Yield of 60% in Neat Film and External Quantum Efficiencies of up
           to 3.9% in Nondoped OLEDs
    • Authors: Tengxiao Liu; Liping Zhu, Cheng Zhong, Guohua Xie, Shaolong Gong, Junfeng Fang, Dongge Ma, Chuluo Yang
      Abstract: Fluorescent emitters have regained intensive attention in organic light emitting diode (OLED) community owing to the breakthrough of the device efficiency and/or new emitting mechanism. This provides a good chance to develop new near-infrared (NIR) fluorescent emitter and high-efficiency device. In this work, a D-π-A-π-D type compound with naphthothiadiazole as acceptor, namely, 4,4′-(naphtho[2,3-c][1,2,5]thiadiazole-4,9-diyl)bis(N,N-diphenylaniline) (NZ2TPA), is designed and synthesized. The photophysical study and density functional theory analysis reveal that the emission of the compound has obvious hybridized local and charge-transfer (HLCT) state feature. In addition, the compound shows aggregation-induced emission (AIE) characteristic. Attributed to its HLCT mechanism and AIE characteristic, NZ2TPA acquires an unprecedentedly high photoluminescent quantum yield of 60% in the neat film, which is the highest among the reported organic small-molecule NIR emitters and even exceeds most phosphorescent NIR materials. The nondoped devices based on NZ2TPA exhibit excellent performance, achieving a maximum external quantum efficiency (EQE) of 3.9% with the emission peak at 696 nm and a high luminance of 6330 cd m−2, which are among the highest in the reported nondoped NIR fluorescent OLEDs. Moreover, the device remains a high EQE of 2.8% at high brightness of 1000 cd m−2, with very low efficiency roll-off.A near-infrared small-molecule emitter exhibits an unprecedentedly high photoluminescent quantum yield of 60% with an emission peak of 683 nm in the neat film. The resulting nondoped organic light emitting diodes achieve a maximum external quantum efficiency of 3.9% with an emission peak of 696 nm.
      PubDate: 2017-02-07T07:35:58.818444-05:
      DOI: 10.1002/adfm.201606384
       
  • A Versatile Plasma Membrane Engineered Cell Vehicle for
           Contact-Cell-Enhanced Photodynamic Therapy
    • Authors: Shi-Ying Li; Wen-Xiu Qiu, Hong Cheng, Fan Gao, Feng-Yi Cao, Xian-Zheng Zhang
      Abstract: In this paper, a plasma membrane engineering approach is reported for tumor targeting drug delivery and contact-cell-enhanced photodynamic therapy (“CONCEPT”) by anchoring functionalized conjugates to cell vehicles. The membrane anchoring conjugates are comprised of a positively charged tetra-arginine peptide sequence, a palmitic-acid-based membrane insertion moiety, and a lysine linker whose ε-amine is modified with camptothecin (CPT), protoporphyrin IX (PpIX), or fluorescein (FAM). The amphipathic CPT, PpIX, or FAM conjugates (short as aCPT, aPpIX, or aFAM, respectively) can easily and steadily anchor or coanchor on the cell membrane of RAW264.7 cells (short as RCs), red blood cells, or mesenchymal stem cells. After anchoring aPpIX in RC cells, the tumor targeting ability and therapeutic effect of aPpIX-anchored RC cells (short as aPRCs) is demonstrated in vitro and in vivo. Importantly, aPRCs exhibit the “CONCEPT” effect, which can enhance the therapeutic efficacy and reduce side effects at the single cell level. Due to the good tumor-targeting ability, aPRCs can efficiently inhibit the tumor growth with no systemic toxicity after photoirradiation by photodynamic therapy.A versatile plasma-membrane-engineered cell vehicle is developed for tumor targeting drug delivery and contact-cell-enhanced photodynamic therapy. This versatile cell vehicle can facilitate the development of personalized treatment for simultaneous tumor theranostics and combination therapy in a more safe way.
      PubDate: 2017-02-07T07:30:45.75284-05:0
      DOI: 10.1002/adfm.201604916
       
  • Cell Membrane Camouflaged Hollow Prussian Blue Nanoparticles for
           Synergistic Photothermal-/Chemotherapy of Cancer
    • Authors: Wansong Chen; Ke Zeng, Hong Liu, Jiang Ouyang, Liqiang Wang, Ying Liu, Hao Wang, Liu Deng, You-Nian Liu
      Abstract: Nanodrug-based cancer therapy has been actively developed in the past decades. The main challenges faced by nanodrugs include poor drug loading capacity, rapid clearance from blood circulation, and low antitumor efficiency with high risk of recurrence. In this work, red blood cell (RBC) membrane camouflaged hollow mesoporous Prussian blue nanoparticles (HMPB@RBC NPs) are fabricated for combination therapy of cancer. The stability, immune evading capacity, and blood retention time of HMPB@RBC NPs are significantly enhanced compared with those of bare HMPB NPs. Doxorubicin (DOX), as a model drug is encapsulated within HMPB@RBC NPs with loading capacity up to 130% in weight. In addition, DOX loaded HMPB@RBC NPs show pH-/photoresponsive release. The in vivo studies demonstrate the outstanding performance of DOX@HMPB@RBC NPs in synergistic photothermal-/chemotherapy of cancer.Red blood cell (RBC) membrane camouflaged hollow mesoporous Prussian blue nanoparticles (HMPB@RBC NPs) are fabricated. With RBC membrane cloaking technique, the stability, immune evading, and blood retention time of HMPB@RBC NPs are significantly increased. Doxorubicin loaded HMPB@RBC NPs show pH-/photoresponsive release properties. The in vivo studies demonstrate that HMPB@RBC NP is a stealthy system for synergistic photothermal-/chemotherapy of cancer.
      PubDate: 2017-02-07T07:30:37.06287-05:0
      DOI: 10.1002/adfm.201605795
       
  • Optically Sintered 2D RuO2 Nanosheets: Temperature-Controlled NO2 Reaction
    • Authors: Seon-Jin Choi; Ji-Soo Jang, Hee Jung Park, Il-Doo Kim
      Abstract: 2D Ru oxide nanosheets (NSs) with optically punched nanoholes are synthesized and integrated on a flexible heating substrate, i.e., silver nanowire (Ag NW)-embedded colorless polyimide (cPI) film, for application in wearable chemical sensors. Multiple discrete pores on the sub-5-nm scale are formed on the basal planes of Ru oxide NSs by irradiation of intense pulsed light. The chemical sensing characteristic of the porous Ru oxide NSs toward nitrogen dioxide (NO2) is investigated under controlled temperatures by applying DC voltage to the Ag NW-embedded cPI film. The improved NO2 responding and recovery kinetics are achieved using the porous Ru oxide NSs with sensitivity of 1.124% at 20 ppm at a film temperature of 80.3 °C. A wireless patch-type sensor module is developed to demonstrate wearable sensing of NO2 using the Ru oxide NSs on Ag NW-embedded cPI heating film. This work paved the new way for application of atomically thin and porous Ru oxide NSs in chemical sensors, which can detect hazardous species in real time.Porous 2D Ru oxide nanosheets (NSs) are achieved on silver nanowire (Ag NW)-embedded colorless polyimide (cPI) heating film for wearable chemical sensors. Atomically thin Ru oxide NSs with sub-5-nm-scale pores exhibit improved response and recovery kinetics under the controlled operating temperatures of an Ag-NW-embedded cPI heater.
      PubDate: 2017-02-07T07:30:31.206549-05:
      DOI: 10.1002/adfm.201606026
       
  • Air- and Active Hydrogen-Induced Electron Trapping and Operational
           Instability in n-Type Polymer Field-Effect Transistors
    • Authors: Hio-Ieng Un; Yu-Qing Zheng, Ke Shi, Jie-Yu Wang, Jian Pei
      Abstract: Organic field-effect transistors (OFETs) have attracted much attention for the next-generation electronics. Despite of the rapid developments of OFETs, operational stability is a big challenge for their commercial applications. Moreover, the actual mechanism behind the degradation of electron transport is still poorly understood. Here, the electrical characteristics of poly{[N,N-9-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene)} (P(NDI2OD-T2)) thin-film transistors (TFTs) as a function of semiconductor/dielectric interfacial property and environment are systematically investigated, in particular, how the copresence of water, oxygen, and active hydrogen on the surface of dielectric leads to a sharp drop-off in threshold voltage. Evidence is found that an acid–base neutralization reaction occurring at the interface, as a combined effect of the chemical instability of dielectrics and the electrochemical instability of organic semiconductors, contributes to the significant electron trapping on the interface of P(NDI2OD-T2) TFTs. Two strategies, increasing the intrinsic electrochemical stability of semiconductor and decreasing the chemical reactivity of gate dielectric, are demonstrated to effectively suppress the reaction and thus improve the operational stability of n-type OFETs. The results provide an alternative degradation pathway to better understand the charge transport instability in n-type OFETs, which is advantageous to construct high-performance OFETs with long-term stability.An acid–base neutralization reaction occurring at the semiconductor/dielectric interface is found to be critical for electron trapping in n-type organic field-effect transistors (OFETs). Two strategies are verified to suppress the reaction and thus improve the operational stability: increasing the electrochemical stability of semiconductors and decreasing the chemical reactivity of dielectrics. These results are advantageous to construct highly stable OFETs.
      PubDate: 2017-02-07T07:25:39.617937-05:
      DOI: 10.1002/adfm.201605058
       
  • Encapsulating a Hydrophilic Chemotherapeutic into Rod-Like Nanoparticles
           of a Genetically Encoded Asymmetric Triblock Polypeptide Improves Its
           Efficacy
    • Authors: Jayanta Bhattacharyya; Isaac Weitzhandler, Shihan Bryan Ho, Jonathan R. McDaniel, Xinghai Li, Lei Tang, Jinyao Liu, Mark Dewhirst, Ashutosh Chilkoti
      Abstract: Encapsulating hydrophilic chemotherapeutics into the core of polymeric nanoparticles can improve their therapeutic efficacy by increasing their plasma half-life, tumor accumulation, and intracellular uptake, and by protecting them from premature degradation. To achieve these goals, a recombinant asymmetric triblock polypeptide (ATBP) that self-assembles into rod-shaped nanoparticles, and which can be used to conjugate diverse hydrophilic molecules, including chemotherapeutics, into their core is designed. These ATBPs consist of three segments: a biodegradable elastin-like polypeptide, a hydrophobic tyrosine-rich segment, and a short cysteine-rich segment, that spontaneously self-assemble into rod-shaped micelles. Covalent conjugation of a structurally diverse set of hydrophilic small molecules, including a hydrophilic chemotherapeutic—gemcitabine—to the cysteine residues also leads to formation of nanoparticles over a range of ATBP concentrations. Gemcitabine-loaded ATBP nanoparticles have significantly better tumor regression compared to free drug in a murine cancer model. This simple strategy of encapsulation of hydrophilic small molecules by conjugation to an ATBP can be used to effectively deliver a range of water-soluble drugs and imaging agents in vivo.Attachment of gemcitabine retains the self-assembly of the asymmetric triblock polypeptide into cylindrical nanoparticles with a drug-rich (blue diamonds) core surrounded by a hydrophobic core (red) and hydrophilic polypeptide corona (black chains).
      PubDate: 2017-02-07T07:25:35.205674-05:
      DOI: 10.1002/adfm.201605421
       
  • A Dual-Functional Persistently Luminescent Nanocomposite Enables
           Engineering of Mesenchymal Stem Cells for Homing and Gene Therapy of
           Glioblastoma
    • Authors: Shu-Qi Wu; Cheng-Xiong Yang, Xiu-Ping Yan
      Abstract: Therapeutically engineered mesenchymal stem cells (MSC) have shown promising capability for glioblastoma (GBM) therapy; however, simultaneous tracking of their migration and long-term fate is urgently needed for clinical application. This study shows the design and fabrication of a dual-functional persistent luminescence nanocomposite (LPLNP-PPT/TRAIL) for effective therapeutic engineering and tracking of MSC in the meantime. LPLNP-PPT/TRAIL shows low-toxicity, near-infrared persistent luminescence emitting without in situ excitation, and superior in vivo deep brain tissue imaging, which can efficiently track the tumortropic migration of the therapeutic engineered MSC. Both in vitro and in vivo findings demonstrate the feasibility of LPLNP-PPT/TRAIL engineered MSC for inducing apoptosis of glioblastoma cells. This work first establishes an LPLNP-based dual-functional platform for cell engineering and provides us implications for GBM-related diagnosis and therapy.A dual-functional persistently luminescent nanocomposite (LPLNP-PPT/TRAIL) with good biocompatibility, capable of emitting near-infrared persistent luminescence without in situ excitation, is developed. Superior in vivo deep brain tissue imaging using this nanocomposite allows for effective therapeutic engineering and tracking of mesenchymal stem cells (MSC) in a glioblastoma (GBM) model. The engineered therapeutic and diagnostic MSC are promising for GBM-related diagnosis and therapy.
      PubDate: 2017-02-06T08:04:42.7397-05:00
      DOI: 10.1002/adfm.201604992
       
  • Dry Transient Electronic Systems by Use of Materials that Sublime
    • Authors: Bong Hoon Kim; Jae-Hwan Kim, Luana Persano, Suk-Won Hwang, Seungmin Lee, Jungyup Lee, Yongjoon Yu, Yongseon Kang, Sang M. Won, Jahyun Koo, Youn Kyoung Cho, Gyum Hur, Anthony Banks, Jun-Kyul Song, Phillip Won, Young Min Song, Kyung-In Jang, Daeshik Kang, Chi Hwan Lee, Dario Pisignano, John A. Rogers
      Abstract: The recent emergence of materials for electronic systems that are capable of programmable self-destruction and/or bio/eco-resorption creates the potential for important classes of devices that cannot be easily addressed using conventional technologies, ranging from temporary biomedical implants to enviromentally benign environmental monitors to hardware secure data systems. Although most previous demonstrations rely on wet chemistry to initiate transient processes of degradation/decomposition, options in “dry transient electronic systems” could expand the range of possible uses. The work presented here introduces materials and composite systems in which sublimation under ambient conditions leads to mechanical fragmentation and disintegration of active devices upon disappearance of a supporting substrate, encapsulation layer, interlayer dielectric and/or gate dielectric. Examples span arrays of transistors based on silicon nanomembranes with specialized device designs to solar cells adapted from commercial components.Unusual materials and device designs enable classes of electronic systems that undergo timed self-destruction induced by ambient sublimation of a supporting substrate, encapsulation layer, interlayer dielectric and/or gate dielectric followed by resulting fragmentation of the remaining ultrathin constituent material elements.
      PubDate: 2017-02-06T08:04:38.144677-05:
      DOI: 10.1002/adfm.201606008
       
  • Design of High Capacity Dissoluble Electrodes for All Transient Batteries
    • Authors: Zhengyang Wang; Kun (Kelvin) Fu, Zhen Liu, Yonggang Yao, Jiaqi Dai, Yibo Wang, Boyang Liu, Liangbing Hu
      Abstract: Transient electronics is an emerging engineering realm that requires materials, devices, and systematic designs with excellent and stable performance in regular operations, but to physically and chemically disappear at a prescribed time with controlled rates once being triggered by external stimulus, leaving no or minimum remnants. In this article, a high energy density rechargeable battery with a fully transient cathode based on tin (Sn)-doped vanadium oxide (V2O5) is designed. Sn-doped V2O5 nanofibers with a high mass loading of 12 mg cm−2 are prepared and no conducting additive or binder is added to fabricate full cells. The transient battery exhibits an areal capacity of 2 mAh cm−2 with a working voltage above 2.0 V and provides 0.27 mAh cm−2 capacity at a current as high as 17.76 mA cm−2. Once triggered by potassium hydroxide (KOH) aqueous solution, the full cell can be completely dissolved into the solution within a few minutes to achieve highly transient capability. This work provides a new approach to achieve an all-transient lithium battery with high areal capacity for transient electronics applications.This study proposes a high energy density rechargeable battery with a fully transient cathode based on tin (Sn)-doped vanadium oxide (V2O5). The transient battery exhibits an areal capacity of 2 mAh cm−2 with a working voltage above 2.0 V, and can be completely transient in potassium hydroxide (KOH) aqueous solution within a few minutes.
      PubDate: 2017-02-06T08:04:30.3572-05:00
      DOI: 10.1002/adfm.201605724
       
  • In Situ Grown Pristine Cobalt Sulfide as Bifunctional Photocatalyst for
           Hydrogen and Oxygen Evolution
    • Authors: Min Zheng; Yong Ding, Li Yu, Xiaoqiang Du, Yukun Zhao
      Abstract: Herein, transition metal chalcogenides of pristine cobalt sulfides are rationally designed to act as robust bifunctional photocatalysts for visible-light-driven water splitting for the first time. Through moderate solvothermal route, cobalt sulfides are synthesized in situ growth and observed by scanning electron microscope image analysis. Noteworthily, 3D hierarchical cobalt sulfides acting as bifunctional photocatalysts are implemented to catalyze the visible-light-driven oxygen evolution reaction and hydrogen evolution reaction. This efficient, earth-abundant, and nonnoble water splitting catalyst for artificial photosynthesis is thoroughly analyzed by various spectroscopic techniques with the aim of investigating its photocatalytic mechanism under visible-light illumination. The main catalyst of CoS-2 exhibits considerable H2 evolution rate of 1196 µmol h−1 g−1 and O2 yield of 63.5%. The efficient activity is attributed to the effective electron transfer between the photosensitizer and catalyst, which is verified by transient absorption experiments. The effective electron transfer between the photosensitizer and catalyst during water oxidation is verified by the dramatic decline of [Ru(bpy)3]3+ concentration in the presence of the catalyst CoS-2. At the same time, transient absorption experiments support a rapid electron transfers from 3EY* (excited photosensitizer eosin-Y) to the catalyst CoS-2 for efficient hydrogen evolution.3D hierarchical cobalt sulfide acts as robust bifunctional photocatalysts for visible-light-driven hydrogen evolution with triethanolamine and eosin-Y, and oxygen evolution with Na2S2O8 and [Ru(bpy)3]2+.
      PubDate: 2017-02-06T08:04:25.500199-05:
      DOI: 10.1002/adfm.201605846
       
  • Printed Microfluidics
    • Authors: Christopher Dixon; Julian Lamanna, Aaron R. Wheeler
      Abstract: Microfluidics has become an important tool that is useful for a wide range of applications. A drawback for microfluidics is that many of the techniques that are commonly used to fabricate devices are not widely accessible, not scalable to high-volume manufacturing processes, or both. Recently, a number of printing strategies that were originally developed for other applications have been applied to microfluidic device fabrication. These techniques, which include inkjet printing (IJP), screen printing (SP), and solid wax printing (SWP), are proposed to have a transformative effect on the field. Here microfluidics and printing, are introduced and a list of favorite examples is provided that highlights the accessibility and scalability that the combination is bringing to the field.A review of the revolution that ink-jet printing, screen printing, and solid-wax printing is bringing to microfluidics (with a focus on continuous flow microfluidics, paper microfluidics, and digital microfluidics).
      PubDate: 2017-02-06T08:01:13.900046-05:
      DOI: 10.1002/adfm.201604824
       
  • High-Performance Photodetectors Based on Organometal Halide Perovskite
           Nanonets
    • Authors: Wenhui Wang; Yurong Ma, Limin Qi
      Abstract: The booming development of organometal halide perovskites has prompted the exploration of morphology-engineering strategies to improve their performance in optoelectronic applications. However, the preparation of optoelectronic devices of perovskites with complex architectures and desirable properties is still highly challenging. Herein, novel CH3NH3PbI3 nanonets and nanobowl arrays are fabricated facilely by using monolayer colloidal crystal (MCC) templates on different substrates. Specifically, highly ordered CH3NH3PbI3 nanonets with high crystallinity are fabricated on a variety of flat substrates, whereas regular CH3NH3PbI3 nanobowl arrays are produced on a coarse substrate. The photodetection performance of the CH3NH3PbI3 nanonet-based photodetectors is significantly enhanced compared to the photodetectors based on conventional CH3NH3PbI3 compact films. Particularly, the nanonet photodetectors exhibit a high responsivity (10.33 A W−1 under 700 nm monochromatic light), which is six times higher than that for the compact CH3NH3PbI3 film devices, fast response speed, and good stability. Owing to the two-dimensional arrayed structure, the CH3NH3PbI3 nanonets exhibit an enhanced light harvesting ability and offer direct carrier transport pathways. Meanwhile, the MCC template brings about larger grain sizes with enhanced crystallinity. Furthermore, the perovskite nanonets can be formed on a flexible polyethylene terephthalate substrate for the fabrication of promising flexible nanonet photodetectors.Highly ordered CH3NH3PbI3 nanonets with high crystallinity are fabricated on a variety of flat substrates through a facile nanosphere lithography approach. When used as a photodetector, the perovskite nanonet exhibits significantly enhanced photoresponsive performance owing to the unique net-like architecture that is beneficial to light harvesting and charge collection.
      PubDate: 2017-02-06T08:01:07.650561-05:
      DOI: 10.1002/adfm.201603653
       
  • Two-Color Emitting Colloidal Nanocrystals as Single-Particle Ratiometric
           Probes of Intracellular pH
    • Authors: Francesco Bruni; Jacopo Pedrini, Caterina Bossio, Beatriz Santiago-Gonzalez, Francesco Meinardi, Wan Ki Bae, Victor I. Klimov, Guglielmo Lanzani, Sergio Brovelli
      Abstract: Intracellular pH is a key parameter in many biological mechanisms and cell metabolism and is used to detect and monitor cancer formation and brain or heart diseases. pH-sensing is typically performed by fluorescence microscopy using pH-responsive dyes. Accuracy is limited by the need for quantifying the absolute emission intensity in living biological samples. An alternative with a higher sensitivity and precision uses probes with a ratiometric response arising from the different pH-sensitivity of two emission channels of a single emitter. Current ratiometric probes are complex constructs suffering from instability and cross-readout due to their broad emission spectra. Here, we overcome such limitations using a single-particle ratiometric pH probe based on dot-in-bulk CdSe/CdS nanocrystals (NCs). These nanostructures feature two fully-separated narrow emissions with different pH sensitivity arising from radiative recombination of core- and shell-localized excitons. The core emission is nearly independent of the pH, whereas the shell luminescence increases in the 3–11 pH range, resulting in a cross-readout-free ratiometric response as strong as 600%. In vitro microscopy demonstrates that the ratiometric response in biologic media resembles the precalibralation curve obtained through far-field titration experiments. The NCs show good biocompatibility, enabling us to monitor in real-time the pH in living cells.Intracellular pH is a key parameter in biological mechanisms and cell metabolism. This study demonstrates single-particle ratiometric pH probes based on hetero-nanocrystals featuring two coexisting emission bands with pH sensitivity. In vitro microscopy demonstrates that the intracellular ratiometric response resembles the precalibration curve obtained through far-field experiments. The nanocrystals show good biocompatibility, enabling us to monitor externally induced pH variations in living cells.
      PubDate: 2017-02-06T07:55:47.491818-05:
      DOI: 10.1002/adfm.201605533
       
  • Rapid Assembly of Large Scale Transparent Circuit Arrays Using PDMS
           Nanofilm Shaped Coffee Ring
    • Authors: Yiwei Li; Weixia Zhang, Jiliang Hu, Yachao Wang, Xiaojun Feng, Wei Du, Ming Guo, Bi-Feng Liu
      Abstract: Rapid and precise assembly of functional nanoparticles into well-defined structures in large scale is motivated by broad fields. In this study, large-scale transparent conductive circuit arrays are rapidly self-assembled by simply pipetting a gold nanoparticles suspension onto a PDMS nanofilm patterned substrate with distinct hydrophilic/hydrophobic areas. The solution firstly self-confines into predefined hydrophilic geometries, followed by assembly of nanoparticles into well-defined circuits with 1D patterns by coffee ring effect. Submicrometer height and submicrometer- to micrometer-width circuit arrays with various shapes are precisely generated by varying the PDMS nanofilm patterns. Thousands of circuits with different geometries are self-assembled simultaneously within 1 min. The conductive circuits show good optical transparency up to 95%. After being transferred into PDMS elastomer sheet by encapsulating, the circuits remain highly conductive during bending and stretching. With the advantages of high-throughput, equipment-free, scalability, and precise control, this technique will open an avenue for fabricating large-scale functional materials for applications in electronics, optoelectronics, and healthcare devices.Large scale transparent circuit arrays are rapidly self-assembled on a PDMS nanofilm patterned substrate. Thousands of circuits are assembled simultaneously within 1 min with a dimension of submicrometer height, submicrometer-to-micrometer width, and up to meter-long length, which also shows precise control over individual geometry. This technique provides a cost-effective solution to meet the increasing demand of electronics, optoelectronics, and healthcare devices.
      PubDate: 2017-02-06T07:55:33.531545-05:
      DOI: 10.1002/adfm.201606045
       
  • Stretchable Active Matrix Inorganic Light-Emitting Diode Display Enabled
           by Overlay-Aligned Roll-Transfer Printing
    • Authors: Minwoo Choi; Bongkyun Jang, Wonho Lee, Seonwoo Lee, Tae Woong Kim, Hak-Joo Lee, Jae-Hyun Kim, Jong-Hyun Ahn
      Abstract: An active matrix-type stretchable display is realized by overlay-aligned transfer of inorganic light-emitting diode (LED) and single-crystal Si thin film transistor (TFT) with roll processes. The roll-based transfer enables integration of heterogeneous thin film devices on a rubber substrate while preserving excellent electrical and optical properties of these devices, comparable to their bulk properties. The electron mobility of the integrated Si-TFT is over 700 cm2 V−1 s−1, and this is attributed to the good interface between the Si channel and the thermally grown SiO2 insulator. The light emission properties of the LED are of wafer quality. The resulting display stably operates under tensile strains up to 40%, over 200 cycles, demonstrating the potential of stretchable displays based on inorganic materials.All-inorganic-based stretchable active matrix display is demonstrated by integration of inorganic light-emitting diode and single-crystal Si thin film transistor. Overlay-aligned roll transfer technique provides good integration of two devices on rubber substrate with outstanding electrical and optical properties. Furthermore, a serpentine-shaped interconnector allows the effective strain division for stable operation of display over 40% applied strain.
      PubDate: 2017-02-06T07:50:42.636854-05:
      DOI: 10.1002/adfm.201606005
       
  • Conception of Stretchable Resistive Memory Devices Based on
           
    • Authors: Chih-Chien Hung; Yu-Cheng Chiu, Hung-Chin Wu, Chien Lu, Cécile Bouilhac, Issei Otsuka, Sami Halila, Redouane Borsali, Shih-Huang Tung, Wen-Chang Chen
      Abstract: It is discovered that the memory-type behaviors of novel carbohydrate-block-polyisoprene (MH-b-PI) block copolymers-based devices, including write-once-read-many-times, Flash, and dynamic-random-access-memory, can be easily controlled by the self-assembly nanostructures (vertical cylinder, horizontal cylinder, and order-packed sphere), in which the MH and PI blocks, respectively, provide the charge-trapping and stretchable function. With increasing the flexible PI block length, the stretchability of the designed copolymers can be significantly improved up to 100% without forming cracks. Thus, intrinsically stretchable resistive memory devices (polydimethylsiloxane(PDMS)/carbon nanotubes(CNTs)/MH-b-PI thin film/Al) using the MH-b-PI thin film as an active layer is successfully fabricated and that using the MH-b-PI12.6k under 100% strain exhibits an excellent ON/OFF current ratio of over 106 (reading at −1 V) with stable Vset around −2 V. Furthermore, the endurance characteristics can be maintained over 500 cycles upon 40% strain. This work establishes and represents a novel avenue for the design of green carbohydrate-derived and stretchable memory materials.Novel stretchable block copolymers, carbohydrate-block-polyisoprene (MH-b-PI), designed for developing fully stretchable resistive memory, are demonstrated. Diverse self-assembly nanostructures with respect to the ratio of charge-trapping MH to stretchable PI can exhibit different memory behaviors. The polymer with longer PI, MH-b-PI12.6k, shows an excellent ON/OFF ratio over 106 upon 100% stretching and the endurance characteristics can be maintained over 500 cycles.
      PubDate: 2017-02-06T07:50:36.118428-05:
      DOI: 10.1002/adfm.201606161
       
  • A Drug-Self-Gated Mesoporous Antitumor Nanoplatform Based on pH-Sensitive
           Dynamic Covalent Bond
    • Authors: Xiaowei Zeng; Gan Liu, Wei Tao, Yue Ma, Xudong Zhang, Fan He, Jianming Pan, Lin Mei, Guoqing Pan
      Abstract: To achieve on-demand drug release, mesoporous silica nanocarriers as antitumor platforms generally need to be gated with stimuli-responsive capping agents. Herein, a “smart” mesoporous nanocarrier that is gated by the drug itself through a pH-sensitive dynamic benzoic–imine covalent bond is demonstrated. The new system, which tactfully bypasses the use of auxiliary capping agents, could also exhibit desirable drug release at tumor tissues/cells and enhanced tumor inhibition. Moreover, a facile dynamic PEGylation via benzoic–imine bond further endows the drug-self-gated nanocarrier with tumor extracellular pH-triggered cell uptake and improves therapeutic efficiency in vivo. In short, the paradigm shift in capping agents here will simplify mesoporous nanomaterials as intelligent drug carriers for cancer therapy. Moreover, the self-gated strategy in this work also shows general potential for self-controlled delivery of natural biomolecules, for example, DNA/RNA, peptides, and proteins, due to their intrinsic amino groups.A drug-self-gated strategy for mesoporous nanocarrier could achieve on-demand drug release at tumor tissue/cells and improved antitumor efficiency. The key is using a pH-sensitive benzoic–imine bond for dynamic conjugation of amino-containing drug molecules (i.e., doxorubicin) on the pore outlets.
      PubDate: 2017-02-03T05:30:53.693751-05:
      DOI: 10.1002/adfm.201605985
       
  • Nanocellulose Aerogels for Supporting Iron Catalysts and In Situ Formation
           of Polyethylene Nanocomposites
    • Authors: Timo Hees; Fan Zhong, Tobias Rudolph, Andreas Walther, Rolf Mülhaupt
      Abstract: Aerogels of nanocellulose (NC) prepared by freeze-drying of cellulose nanofibrils (CNF) hydrogels and followed by impregnation with methylaluminoxane serve as nanoporous organic supports for immobilizing single site iron catalysts such as bisiminopyridine iron(II) complexes. The resulting catalyst systems, exploiting renewable biomaterials as organic supports, are highly active in low pressure ethylene polymerization. They afford simultaneous control of high density polyethylene (HDPE) particle morphology and facile NC dispersion within the HDPE matrix. In the early stage of ethylene polymerization, mesoscopic shape replication and NC-mediated templating yield platelets containing an NC core and a HDPE shell, as confirmed by scanning electron microscopy (SEM) of virgin polyethylene powders. Opposite to conventionally dried CNF hydrogels, forming large agglomerates, this facile NC aerogel-mediated in situ NC/HDPE nanocomposite formation is vastly superior to melt compounding of HDPE with NC, failing to produce such fine NC dispersions. On increasing NC content to 3.0 wt%, both Young's modulus (+50%) and tensile strength (+40%) increase at the expense of elongation at break (−80%). According to the SEM analysis of NC/HDPE morphology, the dispersion of NC nanosheets together with the in situ formation of “shish-kebab” polyethylene fiber-like structures accounted for HDPE matrix reinforcement.Immobilization of highly active iron-based single-site catalysts for ethylene polymerization on nanocellulose (NC) aerogels enables in situ NC/high density polyethylene nanocomposite formation and controlled particle growth by mesoscopic shape replication. Herein, variations of polymerization conditions and mechanical properties of the resulting materials are investigated. Interestingly, superior stiffness and strength are paralleled by the presence of oriented self-reinforcing polyethylene nanostructures (“shish-kebab”).
      PubDate: 2017-02-03T05:30:36.04199-05:0
      DOI: 10.1002/adfm.201605586
       
  • Fast and Controllable Electric-Field-Assisted Reactive Deposited Stable
           and Annealing-Free Perovskite toward Applicable High-Performance Solar
           Cells
    • Authors: Feng Zhou; Hong Liu, Xinwei Wang, Wenzhong Shen
      Abstract: Recently, organic–inorganic hybrid perovskite materials have drawn great attention for their outstanding performance in high-efficiency solar cells. Successful synthesis has been realized either in solution-based chemical deposition or vapor deposition. However, conflicts have never ceased among quality control, growth rate, process complexity, and instrument requirement, which have limited their development toward real applications. In this work, the first electrochemical fabrication of perovskite toward high-efficiency and scalable perovskite solar cells (PSCs) is established. The morphology and crystallization of the CH3NH3PbI3 film can be effectively controlled by simply modulating a few physical parameters. A detailed study on its optoelectronic properties reveals significantly improved film quality and interfacial conditions. Aided by this, the total process does not require standard annealing, which greatly reduces the total growth time from hours to minutes. Up to now, an efficiency of 15.65% has been achieved in planar PSCs under 1 sun AM 1.5 condition, with small hysteresis and efficiency loss under longtime exposure to air. Moreover, high efficiency (10.45%) can be easily attained for large cells (2 cm2). This result will hopefully facilitate research for applicable high-efficiency PSCs and other multicomponent materials as well.The first complete electrochemical fabrication of perovskite has been achieved for perovskite solar cells, with a total time two orders of magnitude less than other presented solution-based methods. High efficiency is realized with large area with efficiency loss of 0.7% from a total of over three weeks' exposure in air, aided by modulation of just a few physical parameters without additional treatments.
      PubDate: 2017-02-03T05:26:07.566227-05:
      DOI: 10.1002/adfm.201606156
       
  • Modulation-Doped Multiple Quantum Wells of Aligned Single-Wall Carbon
           Nanotubes
    • Authors: Natsumi Komatsu; Weilu Gao, Peiyu Chen, Cheng Guo, Aydin Babakhani, Junichiro Kono
      Abstract: Heterojunctions, quantum wells, and superlattices with precise doping profiles are behind today's electronic and photonic devices based on III–V compound semiconductors such as GaAs. Currently, there is considerable interest in constructing similar artificial 3D architectures with tailored electrical and optical properties by using van der Waals junctions of low-dimensional materials. In this study, the authors have fabricated a novel structure consisting of multiple thin (≈20 nm) layers of aligned single-wall carbon nanotubes with dopants inserted between the layers. This “modulation-doped” multiple-quantum-well structure acts as a terahertz polarizer with an ultra-broadband working frequency range (from ≈0.2 to ≈200 THz), a high extinction ratio (20 dB from ≈0.2 to 1 THz), and a low insertion loss (
      PubDate: 2017-02-03T05:25:50.747027-05:
      DOI: 10.1002/adfm.201606022
       
  • Modulation of Spin Dynamics via Voltage Control of Spin-Lattice Coupling
           in Multiferroics
    • Authors: Mingmin Zhu; Ziyao Zhou, Bin Peng, Shishun Zhao, Yijun Zhang, Gang Niu, Wei Ren, Zuo-Guang Ye, Yaohua Liu, Ming Liu
      Abstract: Motivated by the most recent progresses in both magnonics (spin dynamics) and multiferroics fields, this work aims at magnonics manipulation by the magnetoelectric coupling effect. Here, voltage control of magnonics, particularly the surface spin waves, is achieved in La0.7Sr0.3MnO3/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 multiferroic heterostructures. With the electron spin resonance method, a large 135 Oe shift of surface spin wave resonance (≈7 times greater than conventional voltage-induced ferromagnetic resonance shift of 20 Oe) is determined. A model of the spin-lattice coupling effect, i.e., varying exchange stiffness due to voltage-induced anisotropic lattice changes, has been established to explain experiment results with good agreement. Additionally, an “on” and “off” spin wave state switch near the critical angle upon applying a voltage is created. The modulation of spin dynamics by spin-lattice coupling effect provides a platform for realizing energy-efficient, tunable magnonics devices.Magnonics manipulation by the magnetoelectric coupling effect is of great importance in voltage-tunable spin wave applications. Voltage control of spin wave resonance as well as critical angle has been demonstrated in La0.7Sr0.3MnO3/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 multiferroic heterostructures. We related this effect to the spin-lattice coupling, which varies exchange stiffness due to voltage-induced anisotropic lattice changes.
      PubDate: 2017-02-03T05:10:44.457895-05:
      DOI: 10.1002/adfm.201605598
       
  • One-Step All-Solution-Based Au–GO Core–Shell Nanosphere Active Layers
           in Nonvolatile ReRAM Devices
    • Authors: Adila Rani; Dhinesh Babu Velusamy, Filipe Marques Mota, Yoon Hee Jang, Richard Hahnkee Kim, Cheolmin Park, Dong Ha Kim
      Abstract: Nonvolatile resistive random-access memory devices based on graphene-oxide-wrapped gold nanospheres (AuNS@GO) are fabricated following a one-step room-temperature solution-process approach reported herein for the first time. The effect of the thickness of the GO layer (2, 5, and 7 nm) and the size of the synthesized AuNS (15 and 55 nm) are inspected. Reliable bistable switching is observed in the devices made from a flexible substrate and incorporating 5 and 7 nm thick GO-wrapped AuNS, sandwiched between two metal electrodes. Current–voltage measurements show bipolar switching behavior with an ON/OFF ratio of 103 and relatively low operating voltage (−2.5 V). The aforementioned devices unveil remarkable robustness over 100 endurance cycles and a retention of 103 s. Conversely, a 2 nm thick GO layer is shown to be insufficient to allow current passage from the bottom to the top electrodes. The resistive switching mechanism is demonstrated by space charge trapped limited current due to the AuNS in AuNS@GO matrix. The proposed device and methodology herein applied are expected to be attractive candidates for future generation flexible memory devices.Nonvolatile resistive random-access memory devices based on graphene-oxide-wrapped gold nanospheres (AuNS@GO) are fabricated following a one-step room-temperature solution process reported herein for the first time. Current–voltage (I–V) and switching measurements are performed to investigate the bistable memory performance of the fabricated devices: Au/AuNS@GO(2)/Al, Au/AuNS@GO(5)/Al, and Au/AuNS@GO(7)/Al, respectively.
      PubDate: 2017-02-03T05:10:31.895605-05:
      DOI: 10.1002/adfm.201604604
       
  • Top Interface Engineering of Flexible Oxide Thin-Film Transistors by
           Splitting Active Layer
    • Authors: Suhui Lee; Jiyeong Shin, Jin Jang
      Abstract: The effect of active layer (amorphous indium–gallium–zinc oxide, a-IGZO) splitting on the performances of back-channel-etched (BCE) and etch-stopper (ES) thin-film transistors (TFTs) on polyimide substrate is studied. While the performance of BCE TFT is independent of active layer splitting, the performance of ES TFT is improved significantly by splitting the active layer into 2–4 µm width along the channel. The saturation mobility is enhanced from 24.3 to 76.8 cm2 V−1 s−1 and this improvement is confirmed by the operation of a ring oscillator made of the split TFTs also. X-ray photoelectron spectroscopy (XPS) analysis of the split a-IGZO indicates the incorporation of F at the island interface and thus improves the top interface quality, leading to a significant improvement of the top channel TFT mobility from 0.25 to 24.22 cm2 V−1 s−1. This improvement is correlated with bonding of In with F at the top interface according to XPS results. The bias stability, hysteresis, and mechanical stability of the ES a-IGZO TFT are also remarkably improved by splitting a-IGZO active layer.Extremely stable high-performance amorphous indium–gallium–zinc oxide thin-film transistor on plastic substrate by active layer splitting is discussed. The transistors showing the high mobility over 70 cm2 V−1 s−1 and extremely stable behavior under bias stress can be realized by active layer splitting. The improvement is due to the top interface improvement by forming stable metal–F bonding and decrease in the interface state density by F plasma treatment.
      PubDate: 2017-02-02T08:45:43.013819-05:
      DOI: 10.1002/adfm.201604921
       
  • Ultrafast Near-Infrared Light-Triggered Intracellular Uncaging to Probe
           Cell Signaling
    • Authors: Xiuying Li; Zifan Che, Khadijah Mazhar, Theodore J. Price, Zhenpeng Qin
      Abstract: The possibility of regulating cell signaling with high spatial and temporal resolution within individual cells and complex cellular networks has important implications in biomedicine. This article demonstrates a general strategy that uses near-infrared tissue-penetrating laser pulses to uncage biomolecules from plasmonic gold-coated liposomes, i.e., plasmonic liposomes, to activate cell signaling in a nonthermal, ultrafast, and highly controllable fashion. Near-infrared picosecond laser pulse induces transient nanobubbles around plasmonic liposomes. The mechanical force generated from the collapse of nanobubbles rapidly ejects encapsulated compound within 0.1 ms. This article shows that single pulse irradiation triggers the rapid intracellular uncaging of calcein from plasmonic liposomes inside endolysosomes. The uncaged calcein then evenly distributes over the entire cytosol and nucleus. Furthermore, this article demonstrates the ability to trigger calcium signaling in both an immortalized cell line and primary dorsal root ganglion neurons by intracellular uncaging of inositol triphosphate (IP3), an endogenous cell calcium signaling second messenger. Compared with other uncaging techniques, this ultrafast near-infrared light-driven molecular uncaging method is easily adaptable to deliver a wide range of bioactive molecules with an ultrafast optical switch, enabling new possibilities to investigate signaling pathways within individual cells and cellular networks.A new ultrafast intracellular uncaging technique: Picosecond laser pulse (750 nm) triggers calcein uncaging from plasmonic liposomes within 0.1 ms. Cell calcium signaling is activated by intracellular uncaging of inositol triphosphate (IP3), a calcium signaling second messenger. This ultrafast uncaging technique will help investigate and better understand cell signaling and facilitate the development of improved therapies and diagnostics.
      PubDate: 2017-02-01T09:01:09.26247-05:0
      DOI: 10.1002/adfm.201605778
       
  • Antitumor Platelet-Mimicking Magnetic Nanoparticles
    • Authors: Lang Rao; Lin-Lin Bu, Qian-Fang Meng, Bo Cai, Wei-Wei Deng, Andrew Li, Kaiyang Li, Shi-Shang Guo, Wen-Feng Zhang, Wei Liu, Zhi-Jun Sun, Xing-Zhong Zhao
      Abstract: Nanoparticles possess the potential to revolutionize cancer diagnosis and therapy. The ideal theranostic nanoplatform should own long system circulation and active cancer targeting. Additionally, it should be nontoxic and invisible to the immune system. Here, the authors fabricate an all-in-one nanoplatform possessed with these properties for personalized cancer theranostics. Platelet-derived vesicles (PLT-vesicles) along with their membrane proteins are collected from mice blood and then coated onto Fe3O4 magnetic nanoparticles (MNs). The resulting core–shell PLT-MNs, which inherit the long circulation and cancer targeting capabilities from the PLT membrane shell and the magnetic and optical absorption properties from the MN core, are finally injected back into the donor mice for enhanced tumor magnetic resonance imaging (MRI) and photothermal therapy (PTT). Meanwhile, it is found that the PTT treatment impels PLT-MNs targeting to the PTT sites (i.e., tumor sites), and exactly, in turn, the enhanced targeting of PLT-MNs to tumor sites can improve the PTT effects. In addition, since the PLT membrane coating is obtained from the mice and finally injected into the same mice, PLT-MNs exhibit stellar immune compatibility. The work presented here provides a new angle on the design of biomimetic nanoparticles for personalized diagnosis and therapy of various diseases.Platelet (PLT) membranes are collected from mice blood and further used to coat magnetic nanoparticles (MNs). And the resulting platelet-mimicking particles (PLT-MNs) are then injected back into the donor mice for enhanced tumor magnetic resonance imaging and photothermal therapy. This work presents a new angle on the design of advanced functional materials for personalized cancer theranostics.
      PubDate: 2017-02-01T05:31:26.011491-05:
      DOI: 10.1002/adfm.201604774
       
  • Coexistence of Grain-Boundaries-Assisted Bipolar and Threshold Resistive
           Switching in Multilayer Hexagonal Boron Nitride
    • Authors: Chengbin Pan; Yanfeng Ji, Na Xiao, Fei Hui, Kechao Tang, Yuzheng Guo, Xiaoming Xie, Francesco M. Puglisi, Luca Larcher, Enrique Miranda, Lanlan Jiang, Yuanyuan Shi, Ilia Valov, Paul C. McIntyre, Rainer Waser, Mario Lanza
      Abstract: The use of 2D materials to improve the capabilities of electronic devices is a promising strategy that has recently gained much interest in both academia and industry. However, while the research in 2D metallic and semiconducting materials is well established, detailed knowledge and applications of 2D insulators are still scarce. In this paper, the presence of resistive switching (RS) in multilayer hexagonal boron nitride (h-BN) is studied using different electrode materials, and a family of h-BN-based resistive random access memories with tunable capabilities is engineered. The devices show the coexistence of forming free bipolar and threshold-type RS with low operation voltages down to 0.4 V, high current on/off ratio up to 106, and long retention times above 10 h, as well as low variability. The RS is driven by the grain boundaries (GBs) in the polycrystalline h-BN stack, which allow the penetration of metallic ions from adjacent electrodes. This reaction can be boosted by the generation of B vacancies, which are more abundant at the GBs. To the best of our knowledge, h-BN is the first 2D material showing the coexistence of bipolar and threshold RS, which may open the door to additional functionalities and applications.The presence of resistive switching in multilayer hexagonal boron nitride (h-BN) is studied using metallic and graphene electrodes, and a family of h-BN-based resistive random access memories with tunable capabilities is engineered.
      PubDate: 2017-02-01T05:31:15.862254-05:
      DOI: 10.1002/adfm.201604811
       
  • Single Molecular Wells–Dawson-Like Heterometallic Cluster for the In
           Situ Functionalization of Ordered Mesoporous Carbon: A T 1- and
           T 2-Weighted Dual-Mode Magnetic Resonance Imaging Agent and Drug Delivery
           System
    • Authors: Qianqian Zhang; Peiyuan Wang, Yun Ling, Xiaomin Li, Lixue Xia, Yongtai Yang, Xiaofeng Liu, Fan Zhang, Yaming Zhou
      Abstract: Developing a feasible way to prepare highly dispersed heterometallic nanoparticles incorporated in porous carbon composites is of significant importance for multifunctional materials. In this work, heterometallic γ-Fe2O3 and GdPO4 nanoparticles that are incorporated in ordered mesoporous carbon composites are facilely prepared by a one-pot in situ method using a Wells–Dawson-like cluster of [Fe6Gd6(μ3-O)2(CO3)(O3PPh)6(O2CtBu)18] ({Fe6Gd6P6} for short) as the precursor. It is verified that the γ-Fe2O3 and GdPO4 nanoparticles are highly dispersed and embedded into the carbon matrix with a particle size smaller than 5 nm, even when the carbon matrix is changed from 2D hexagonal P6mm to 3D body-centered cubic Im-3m symmetry. Additionally, a formation mechanism is proposed. Furthermore, dual-mode magnetic resonance (MR) imaging and drug carrier properties are evaluated by in vitro experiments, which show a satisfactory T1- and T2-weighted MR imaging effect with r1 and r2 relaxivity values of 2.7 and 183.7 mM−1 s−1, respectively, and doxorubicin hydrochloride carrier amount of 102 mg g−1, identifying a combined function for potential diagnostic and therapy.Highly heterometallic γ-Fe2O3 and GdPO4 nanoparticle-incorporated ordered mesoporous carbons are facilely prepared by a one-pot in situ method using a Wells–Dawson-like cluster of [Fe6Gd6(μ3-O)2(CO3)(O3PPh)6(O2CtBu)18] as the precursor. In vitro experiments confirm the prepared composite displays a satisfactory T1- and T2-weighted magnetic resonance imaging effect and a drug carrier ability simultaneously, suggesting a potential application as a magnetic resonance diagnostic and therapy agent.
      PubDate: 2017-02-01T05:26:16.859692-05:
      DOI: 10.1002/adfm.201605313
       
  • Albumin Biomimetic Nanocorona Improves Tumor Targeting and Penetration for
           Synergistic Therapy of Metastatic Breast Cancer
    • Authors: Haiqiang Cao; Lili Zou, Bin He, Lijuan Zeng, Yongzhuo Huang, Haijun Yu, Pengcheng Zhang, Qi Yin, Zhiwen Zhang, Yaping Li
      Abstract: The synergistic combination of photothermal and RNA interference therapy demonstrates great potential for effective treatment of metastatic breast cancer, but their efficacy is limited by the poor delivery efficiency to tumor. Herein, it is reported that an albumin biomimetic nanocorona (DRI-S@HSA) can accomplish the high accumulation and deep penetration within tumor tissues, thereby holding great promise for synergistic therapy. DRI-S@HSA is prepared by camouflaging human serum albumin (HSA) onto an IR-780 and small interfering RNA-loaded cell-penetrating peptide nanoassembly (DRI-S). In metastatic 4T1 breast cancer cells, DRI-S@HSA can be largely internalized, and cause significant inhibition on cell migration and proliferation in combination with laser irradiation. Surprisingly, in vivo, the albumin camouflage in DRI-S@HSA produces a 2.5-fold enhancement on tumor accumulation compared to the undecorated DRI-S, and dramatically improves the deep penetration capacity in tumor mass. Moreover, a single DRI-S@HSA treatment plus 808 nm laser irradiation results in an 83.6% inhibition on tumor growth and efficient prevention of lung metastases. Taken together, the findings can provide an encouraging biomimetic tumor-targeted drug delivery strategy to inhibit tumor progression and prevent lung metastases of breast cancer.The targeted drug delivery of nanomedicine to tumor remains a great challenge for combinational therapy of metastatic breast cancer. Herein, an albumin biomimetic nanocorona (DRI-S@HSA) loading photothermal agent IR-780 and Twist small interfering RNA can accomplish high accumulation and deep penetration within tumor tissues, thereby holding great promise for synergistic therapy of tumor progression and metastasis of breast cancer.
      PubDate: 2017-01-30T09:01:03.082-05:00
      DOI: 10.1002/adfm.201605679
       
  • Advent of 2D Rhenium Disulfide (ReS2): Fundamentals to Applications
    • Authors: Mohammad Rahman; Kenneth Davey, Shi-Zhang Qiao
      Abstract: Rhenium disulfide (ReS2) is a two-dimensional (2D) group VII transition metal dichalcogenide (TMD). It is attributed with structural and vibrational anisotropy, layer-independent electrical and optical properties, and metal-free magnetism properties. These properties are unusual compared with more widely used group VI-TMDs, e.g., MoS2, MoSe2, WS2 and WSe2. Consequently, it has attracted significant interest in recent years and is now being used for a variety of applications including solid state electronics, catalysis, and, energy harvesting and energy storage. It is anticipated that ReS2 has the potential to be equally used in parallel with isotropic TMDs from group VI for all known applications and beyond. Therefore, a review on ReS2 is very timely. In this first review on ReS2, we critically analyze the available synthesis procedures and their pros/cons, atomic structure and lattice symmetry, crystal structure, and growth mechanisms with an insight into the orientation and architecture of domain and grain boundaries, decoupling of structural and vibrational properties, anisotropic electrical, optical, and magnetic properties impacted by crystal imperfections, doping and adatoms adsorptions, and contemporary applications in different areas.ReS2 is reviewed comprehensively for the first time, including the state-of-the-art progress and prospects of the synthesis, fundamental properties, and applications.
      PubDate: 2017-01-30T06:07:53.24749-05:0
      DOI: 10.1002/adfm.201606129
       
  • Large-Scale LiO2 Pouch Type Cells for Practical Evaluation and
           Applications
    • Authors: Hyeon-Ji Shin; Won-Jin Kwak, Doron Aurbach, Yang-Kook Sun
      Abstract: Due to their high theoretical specific capacity and energy density, LiO2 batteries are considered as candidates for next-generation battery systems in place of conventional Li-ion batteries for advanced applications such as electric vehicles. However, low energy efficiency, poor cycle life, and Li-metal safety issues make the use of LiO2 batteries yet impractical. In addition, actual cell capacities are very low, and since only small-scale electrodes are currently tested, it is hard to predict the properties of large-size electrodes and cells, thus evaluating and judging real practical challenges related to this battery technology. In this work, the behavior of pouch-type LiO2 cells using 3 × 5 cm2 sized electrodes is investigated and it is confirmed that Li-metal is a key issue for the upscale of LiO2 cells. This study can help to determine which parameters are the most important for developing practical LiO2 batteries.The behavior of pouch-type LiO2 cells using large-size electrodes is investigated for evaluating and judging real, practical challenges related to this battery technology. Despite the use of optimized cells, unavoidable failure due to formation of LiOH on the Li-anode surface is discovered, which could not be easily distinguished in small-sized cells within several cycles.
      PubDate: 2017-01-30T06:00:55.077371-05:
      DOI: 10.1002/adfm.201605500
       
  • A Leaky-Integrate-and-Fire Neuron Analog Realized with a Mott Insulator
    • Authors: Pablo Stoliar; Julien Tranchant, Benoit Corraze, Etienne Janod, Marie-Paule Besland, Federico Tesler, Marcelo Rozenberg, Laurent Cario
      Abstract: During the last half century, the tremendous development of computers based on von Neumann architecture has led to the revolution of the information technology. However, von Neumann computers are outperformed by the mammal brain in numerous data-processing applications such as pattern recognition and data mining. Neuromorphic engineering aims to mimic brain-like behavior through the implementation of artificial neural networks based on the combination of a large number of artificial neurons massively interconnected by an even larger number of artificial synapses. In order to effectively implement artificial neural networks directly in hardware, it is mandatory to develop artificial neurons and synapses. A promising advance has been made in recent years with the introduction of the components called memristors that might implement synaptic functions. In contrast, the advances in artificial neurons have consisted in the implementation of silicon-based circuits. However, so far, a single-component artificial neuron that will bring an improvement comparable to what memristors have brought to synapses is still missing. Here, a simple two-terminal device is introduced, which can implement the basic functions leaky integrate and fire of spiking neurons. Remarkably, it has been found that it is realized by the behavior of strongly correlated narrow-gap Mott insulators subject to electric pulsing.The mammal brain is based on a network of closely connected neurons and synapses. The implementation of artificial neural networks directly in hardware requires therefore to develop artificial neurons and synapses that can be integrated in high-density chips. Here, a two-terminal device made of narrow-gap strongly correlated Mott insulators is demonstrated, which implements the processing functions of the leaky-integrate-and-fire artificial neuron.
      PubDate: 2017-01-30T06:00:46.067035-05:
      DOI: 10.1002/adfm.201604740
       
  • Superior Fatigue Resistant Bioinspired Graphene-Based Nanocomposite via
           Synergistic Interfacial Interactions
    • Authors: Sijie Wan; Feiyu Xu, Lei Jiang, Qunfeng Cheng
      Abstract: Excellent fatigue resistance is a prerequisite for flexible energy devices to achieve high and stable performance under repeated deformation state. Inspired by the sophisticated interfacial architecture of nacre, herein a super fatigue-resistant graphene-based nanocomposite with integrated high tensile strength and toughness through poly(dopamine)-nickel ion (Ni2+) chelate architecture that mimics byssal threads is demonstrated. These kind of synergistic interfacial interactions of covalent and ionic bonding effectively suppress the crack propagation in the process of fatigue testing, resulting in superhigh fatigue life of this bioinspired graphene-based nanocomposite (BGBN). In addition, the electrical conductivity is well kept after fatigue testing. The proposed synergistic interfacial interactions could serve as a guideline for fabricating high-performance multifunctional BGBNs with promising applications in flexible energy devices, such as flexible electrodes for supercapacitors and lithium batteries, etc.Inspired by sophisticated interfacial architecture of nacre, a super fatigue-resistant graphene-based nanocomposite via synergistic interfacial interactions of covalent and ionic bonding, which shows promising applications in flexible energy devices, is demonstrated.
      PubDate: 2017-01-27T09:50:34.0832-05:00
      DOI: 10.1002/adfm.201605636
       
  • Gas Phase Synthesis of Multifunctional Fe-Based Nanocubes
    • Authors: Jerome Vernieres; Stephan Steinhauer, Junlei Zhao, Audrey Chapelle, Philippe Menini, Nicolas Dufour, Rosa E. Diaz, Kai Nordlund, Flyura Djurabekova, Panagiotis Grammatikopoulos, Mukhles Sowwan
      Abstract: Magnetron-sputtering inert-gas condensation is an emerging technique offering single-step, chemical-free synthesis of nanoparticles with well-defined morphologies optimized for specific applications. In this study, the authors report a flexible approach to produce Fe nanocubes as building blocks for high-performance NO2 gas sensor devices, and hybrid FeAu nanocubes with magneto-plasmonic properties. Considering that nucleation happens within a short distance from the sputtering target, the authors utilize the high-permeability and resultant screening effect induced by magnetic Fe targets of various thicknesses to manipulate the magnetic field configuration and plasma confinement. The authors thus readily switch from bimodal to single-Gaussian size distributions of Fe nanocubes by modifying their primordial thermal environments, as explained by a combination of modeling methods. Simultaneously, the authors obtain a material yield increase of more than one order of magnitude compared to experiments using postgrowth mass filtration. The effectiveness of the method is demonstrated by the deposition of Fe nanocubes on microhotplate devices, leading to unprecedented NO2 detection performance for Fe-based chemoresistive gas sensors. The exceedingly low detection limit down to 3 ppb is attributed to a morphological change in operando from Fe/Fe-oxide core/shell to specific hollow-nanocube structures, as revealed by in situ environmental transmission electron microscopy.A flexible gas-phase synthesis method is demonstrated for the fabrication of multifunctional hybrid Fe nanocubes by means of morphological control during formation. Utilizing this approach, magneto-plasmonic properties of Fe nanocubes are tailored by Au-doping, and Fe-based gas sensors are realized with remarkable performance for NO2 detection down to concentrations as low as 3 ppb.
      PubDate: 2017-01-25T08:50:42.400375-05:
      DOI: 10.1002/adfm.201605328
       
  • Harvesting of Living Cell Sheets by the Dynamic Generation of Diffractive
           Photothermal Pattern on PEDOT
    • Authors: Jongbeom Na; June Seok Heo, Minsu Han, Hanwhuy Lim, Hyun Ok Kim, Eunkyoung Kim
      Abstract: Near infrared (NIR) photothermal pattern on conductive polymer film enables unique approaches to harvest large-area cell sheets with various patterns without the use of patterned culture dish. The NIR photothermal pattern is generated from a patterned optical lens (POL), which creates a dynamic near IR light pattern and the corresponding photothermal pattern (PTP) on the polymer film. The POL is prepared from transparent polydimethylsiloxane designed to generate various light patterns. The PTPs allow a noninvasive harvest of cultured cells as an intact living cell sheet with a high harvesting efficiency (ηcell > 100). Various PTPs are generated by the diffraction of NIR light through POLs having different micropatterns, which afford cell sheets with a desired pattern without changing the original cell morphology at cultured state. Furthermore, a large-area living cell sheet is obtained with a detached area larger than 19 cm2, which is the largest living cell sheet up to date. Further optical engineering of the harvesting system allows multiple productions of cell sheets with one dose of light. It is possible to harvest cell sheets not only from human fibroblast cells but also from human adipose-derived stem cells, indicating that the method can be applied to engineer various cells.Through a dynamic control of near infrared light diffraction, the photothermal patterns are generated onto the poly(3,4-ethylenedioxythiophene) surface with various patterns such as line, square, and hexagonal. This optical method can harvest not only the patterned and large-area cell sheets but also multiple cell sheets at once.
      PubDate: 2017-01-24T07:50:57.919139-05:
      DOI: 10.1002/adfm.201604260
       
  • Novel Direct Nanopatterning Approach to Fabricate Periodically
           Nanostructured Perovskite for Optoelectronic Applications
    • Authors: Jian Mao; Wei E. I. Sha, Hong Zhang, Xingang Ren, Jiaqing Zhuang, Vellaisamy A. L. Roy, Kam Sing Wong, Wallace C. H. Choy
      Abstract: While indirectly patterned organic–inorganic hybrid perovskite nanostructures have been extensively studied for use in perovskite optoelectronic devices, it is still challenging to directly pattern perovskite thin films because perovskite is very sensitive to polar solvents and high-temperature environments. Here, a simple and low-cost approach is proposed to directly pattern perovskite solid-state films into periodic nanostructures. The approach is basically perovskite recrystallization through phase transformation with the presence of a periodic mold on an as-prepared solid-state perovskite film. Interestingly, this study simultaneously achieves not only periodically patterned perovskite nanostructures but also better crystallized perovskites and improved optical properties, as compared to its thin film counterpart. The improved optical properties can be attributed to the light extraction and increased spontaneous emission rate of perovskite gratings. By fabricating light-emitting diodes using the periodic perovskite nanostructure as the emission layers, approximately twofold higher radiance and lower threshold than the reference planar devices are achieved. This work opens up a new and simple way to fabricate highly crystalline and large-area perovskite periodic nanostructures for low-cost production of high-performance optoelectronic devices.A new and simple direct nanopatterning approach for fabricating highly crystalline and large-area periodic perovskite nanostructures is proposed. This approach is suitable for preparing perovskite nanostructures with different configurations. More importantly, the prepared periodic perovskite nanostructures can be fabricated into different optoelectronic devices, such as solar cells, light-emitting diodes, laser diodes, and photodetectors.
      PubDate: 2017-01-24T07:50:41.829774-05:
      DOI: 10.1002/adfm.201606525
       
  • Controlled Sub-Micrometer Hierarchical Textures Engineered in Polymeric
           Fibers and Microchannels via Thermal Drawing
    • Authors: Tung Nguyen-Dang; Alba C. de Luca, Wei Yan, Yunpeng Qu, Alexis G. Page, Marco Volpi, Tapajyoti Das Gupta, Stéphanie P. Lacour, Fabien Sorin
      Abstract: The controlled texturing of surfaces at the micro- and nanoscales is a powerful method for tailoring how materials interact with liquids, electromagnetic waves, or biological tissues. The increasing scientific and technological interest in advanced fibers and fabrics has triggered a strong motivation for leveraging the use of textures on fiber surfaces. Thus far however, fiber-processing techniques have exhibited an inherent limitation due to the smoothing out of surface textures by polymer reflow, restricting achievable feature sizes. In this article, a theoretical framework is established from which a strategy is developed to reduce the surface tension of the textured polymer, thus drastically slowing down thermal reflow. With this approach the fabrication of potentially kilometers-long polymer fibers with controlled hierarchical surface textures of unprecedented complexity and with feature sizes down to a few hundreds of nanometers is demonstrated, two orders of magnitude below current configurations. Using such fibers as molds, 3D microchannels are also fabricated with textured inner surfaces within soft polymers such as poly(dimethylsiloxane), at dimensions and a degree of simplicity impossible to reach with current techniques. This strategy for the texturing of high curvature surfaces opens novel opportunities in bioengineering, regenerative scaffolds, microfluidics, and smart textiles.A novel approach for the simple fabrication of fibers and microchannels with controlled sub-micrometer surface textures is demonstrated. It is based on surface tension engineering during thermal drawing. This enables to tailor a variety of surface properties, from optical to the influence on the growth of biological cells, for advanced fibers and textiles.
      PubDate: 2017-01-24T04:30:50.224687-05:
      DOI: 10.1002/adfm.201605935
       
  • Ultrasmall CuCo2S4 Nanocrystals: All-in-One Theragnosis Nanoplatform with
           Magnetic Resonance/Near-Infrared Imaging for Efficiently Photothermal
           Therapy of Tumors
    • Authors: Bo Li; Fukang Yuan, Guanjie He, Xiaoyu Han, Xin Wang, Jinbao Qin, Zheng Xiao Guo, Xinwu Lu, Qian Wang, Ivan P. Parkin, Chengtie Wu
      Abstract: Copper-based ternary bimetal chalcogenides have very promising potential as multifunctional theragnosis nanoplatform for photothermal treatment of tumors. However, the design and synthesis of such an effective platform remains challenging. In this study, hydrophilic CuCo2S4 nanocrystals (NCs) with a desirable size of ≈10 nm are synthesized by a simple one-pot hydrothermal route. The as-prepared ultrasmall CuCo2S4 NCs show: 1) intense near-infrared absorption, which is attributed to 3d electronic transitions from the valence band to an intermediate band, as identified by density functional theory calculations; 2) high photothermal performance with a photothermal conversion efficiency up to 73.4%; and 3) capability for magnetic resonance (MR) imaging, as a result of the unpaired 3d electrons of cobalt. Finally, it is demonstrated that the CuCo2S4 NCs are a promising “all-in-one” photothermal theragnosis nanoplatform for photothermal cancer therapy under the irradiation of a 915 nm laser at a safe power density of 0.5 W cm−2, guided by MR and infrared thermal imaging. This work further promotes the potential applications of ternary bimetal chalcogenides for photothermal theragnosis therapy.Ultrasmall CuCo2S4 nanocrystals are developed as an efficient photothermal theragnosis agent. The nanocrystals exhibit intense near-infrared absorption attributed to 3d electronic transitions from the valence band to an intermediate band, as identified by density functional theory calculations, and capability for magnetic resonance imaging, as a result of the unpaired 3d electrons of cobalt.
      PubDate: 2017-01-23T08:20:57.459277-05:
      DOI: 10.1002/adfm.201606218
       
  • Redox-Responsive and Drug-Embedded Silica Nanoparticles with Unique
           Self-Destruction Features for Efficient Gene/Drug Codelivery
    • Authors: Qing Zhang; Chuanan Shen, Nana Zhao, Fu-Jian Xu
      Abstract: The development of advanced gene/drug codelivery carriers with stimuli-responsive release manner for complementary cancer therapy is desirable. In this study, novel disulfide-bridged and doxorubicin (DOX)-embedded degradable silica nanoparticles (DS-DOX) with unique self-destruction features are synthesized by a facile one-pot method. In order to realize codelivery of genes and drugs, the surface of DS-DOX nanoparticles is readily functionalized with the assembled polycation (CD-PGEA), comprising one β-cyclodextrin core and two ethanolamine-functionalized poly(glycidyl methacrylate) arms, to achieve DS-DOX-PGEA. The redox-responsive self-destruction behavior of DS-DOX imparts DS-DOX-PGEA with a better ability to release anticancer drug DOX, while the low-toxic hydroxyl-rich CD-PGEA brushes can efficiently deliver genes for cancer treatment. Very interestingly, the degradation process of DS-DOX starts from the outside, while the destruction of the degradable silica (DS) nanoparticles without DOX begins from the center of the nanoparticles. The embedded DOX inside the DS-DOX nanoparticles can significantly influence the structures and facilitate the cellular uptake and the subsequent gene transfection. The as-developed DS-DOX-PGEA nanostructure with coordinating biodegradability, stimuli-responsiveness, and controlled release manner might be desirable gene/drug codelivery carriers for clinical cancer treatment.Disulfide-bridged and DOX-embedded degradable silica nanohybrids with unique self-destruction features and stimuli-responsive release manner are constructed as gene/drug codelivery carriers for complementary cancer therapy.
      PubDate: 2017-01-23T08:15:44.436091-05:
      DOI: 10.1002/adfm.201606229
       
  • Toughness and Fracture Properties in Nacre-Mimetic Clay/Polymer
           Nanocomposites
    • Authors: Maria Morits; Tuukka Verho, Juhana Sorvari, Ville Liljeström, Mauri A. Kostiainen, André H. Gröschel, Olli Ikkala
      Abstract: Nacre inspires researchers by combining stiffness with toughness by its unique microstructure of aligned aragonite platelets. This brick-and-mortar structure of reinforcing platelets separated with thin organic matrix has been replicated in numerous mimics that can be divided into two categories: microcomposites with aligned metal oxide microplatelets in polymer matrix, and nanocomposites with self-assembled nanoplatelets—usually clay or graphene oxide—and polymer. While microcomposites have shown exceptional fracture toughness, current fabrication methods have limited nacre-mimetic nanocomposites to thin films where fracture properties remained unexplored. Yet, fracture resistance is the defining property of nacre, therefore centrally important in any mimic. Furthermore, to make use of these properties in applications, bulk materials are required. Here, up to centimeter-thick nacre-mimetic clay/polymer nanocomposites are produced by the lamination of self-assembled films. The aligned clay nanoplatelets are separated by poly(vinyl alcohol) matrix, with 106–107 nanoplatelets on top of each other in the bulk plates. Fracture testing shows crack deflection and a fracture toughness of 3.4 MPa m1/2, not far from nacre. Flexural tests show high stiffness (25 GPa) and strength (220 MPa) that, despite the hydrophilic constituents, are not substantially affected by exposure to humidity.Nacre-inspired nanocomposites are constructed by evaporation induced self-assembly of nanoclay and polymer, followed by lamination. Bulk dimensions are achieved beyond the previously studied films, which allowed exploring hitherto unaccessible fracture toughness and flexural properties in self-assembled highly reinforced aligned nanocomposites. High toughness of 3.4 MPa m1/2 is shown, as well as crack deflection in bending, approaching those of nacre.
      PubDate: 2017-01-23T07:50:50.648676-05:
      DOI: 10.1002/adfm.201605378
       
  • Combinatorial Evolution of Biomimetic Magnetite Nanoparticles
    • Authors: Jos J. M. Lenders; Lukmaan A. Bawazer, David C. Green, Harshal R. Zope, Paul H. H. Bomans, Gijsbertus de With, Alexander Kros, Fiona C. Meldrum, Nico A. J. M. Sommerdijk
      Abstract: Inspired by Nature's capacity to synthesize well-defined inorganic nanostructures, such as the magnetite particles produced by magnetotactic bacteria, genetic algorithms are employed to combinatorially optimize the aqueous synthesis of magnetite (Fe3O4) nanoparticles through the action of copolypeptide additives. An automated dispensing system is used to prepare and rapidly screen hundreds of mineralization reactions with randomized conditions, varying ferrous iron, base, oxidant, and polypeptide chemistry. Optimization over multiple generations allows identification of conditions under which the copolypeptides promote magnetite formation where this does not occur in their absence. It is found that nanoparticle size, size distribution, and shape can be tuned by the concentrations and compositions of the copolypeptides, and that the reaction pH is the most important factor in controlling the crystalline phase. This approach should be broadly applicable to the syntheses of solid-state materials and represents a valuable strategy for extending biomimetic mineralization to the production of technological materials.Genetic algorithms are employed to combinatorially optimize the bioinspired aqueous synthesis of magnetite nanoparticles in the presence of copolypeptide additives. This strategy allows magnetite formation where this does not occur in their absence, and nanoparticle size, size distribution, and shape to be tuned by the action of the copolypeptides. It therewith extends biomimetic mineralization to the production of technological materials.
      PubDate: 2017-01-23T07:45:57.907099-05:
      DOI: 10.1002/adfm.201604863
       
  • Surface Modification of Al Foils for Aluminum Electrolytic Capacitor
    • Authors: Xianfeng Du; Baige Lin, Bing Li, Tianyu Feng, Shengchun Mao, Youlong Xu
      Abstract: Miniaturization and light weight of aluminum electrolytic capacitor can be achieved via the enhancement in the specific capacitance of anodized aluminum foils resulted from the introduction of compounds with high permittivity into dielectric layer. However, the electrostatic repulsion between the compounds and aluminum substrates hinders this introduction of the compounds, leading to a limited improvement in the specific capacitance. In this work, a novel strategy has been developed to promote the deposition of TiO2 on the surface of aluminum foils by surface modification with polyvinyl alcohol, which sharply decreases the electrostatic repulsion and dramatically increases the mass of deposited TiO2. The evolution of composition and morphology during the process are studied and the capacitor performance of aluminum foils with various treatments is investigated. Interestingly, after surface modification, a specific capacitance of 131.5 µF cm−2 under the withstanding voltage of 21.2 V is obtained, and there is about 60% enhancement in the specific capacitance compared with those without TiO2, and about 30% enhancement compared with those without surface modification, respectively. The specific capacitance obtained is the highest one for aluminum electrolytic capacitor reported to date. These outstanding performances exhibit great potential of this strategy for commercial application on aluminum electrolytic capacitor.A novel strategy is developed to promote the deposition of TiO2 on the surface of aluminum foils by surface modification with polyvinyl alcohol, which results in a high specific capacitance of 131.5 µF cm−2 under the withstanding voltage of 21.2 V and an about 60% enhancement in the specific capacitance compared with those without TiO2.
      PubDate: 2017-01-23T07:45:47.877869-05:
      DOI: 10.1002/adfm.201606042
       
  • Unraveling Surface Basicity and Bulk Morphology Relationship on Covalent
           Triazine Frameworks with Unique Catalytic and Gas Adsorption Properties
    • Authors: Giulia Tuci; Moritz Pilaski, Housseinou Ba, Andrea Rossin, Lapo Luconi, Stefano Caporali, Cuong Pham-Huu, Regina Palkovits, Giuliano Giambastiani
      Abstract: Activity and selectivity are key features at the basis of an efficient catalytic system for promoting the steam- and oxygen-free dehydrogenation (DDH) of ethylbenzene to styrene. The catalyst stability under severe reaction conditions, the reduction of leaching of its active sites, and their resistance to deactivation phenomena on stream are other fundamental aspects to keep in mind while synthesizing new catalytic materials for the process. Although the recent use of single-phase (doped or undoped) carbon nanomaterials has significantly contributed to improving this catalysis, the relationship between materials morphology and their chemical surface properties still remains to be addressed. Here, a class of highly microporous, N-doped covalent triazine frameworks (CTFs) with superior activity and stability in the DDH compared to the benchmark systems of the state-of-the-art is reported. Notably, a comparative analysis of their chemico-physical properties has unveiled the role of the “chemically accessible” surface basicity on the catalyst passivation on stream. Finally, the unique properties of the synthesized CTFs are demonstrated by their excellent H2 storage capability and CO2 absorption that rank among the highest reported so far for related systems.Highly microporous N-doped covalent triazine frameworks show superior activity and stability in the ethylbenzene dehydrogenation to styrene compared to state-of-the-art benchmark systems. Their unique chemico-physical properties also demonstrate their superior H2 storage capability as well as their CO2 absorption that ranks among the highest reported so far for related systems.
      PubDate: 2017-01-13T07:41:15.100241-05:
      DOI: 10.1002/adfm.201605672
       
  • Engineered Extracellular Matrices as Biomaterials of Tunable Composition
           and Function
    • Authors: Paul Emile Bourgine; Emanuele Gaudiello, Benjamin Pippenger, Claude Jaquiery, Thibaut Klein, Sebastien Pigeot, Atanas Todorov, Sandra Feliciano, Andrea Banfi, Ivan Martin
      Abstract: Engineered and decellularized extracellular matrices (ECM) are receiving increasing interest in regenerative medicine as materials capable to induce cell growth/differentiation and tissue repair by physiological presentation of embedded cues. However, ECM production/decellularization processes and control over their composition remain primary challenges. This study reports engineering of ECM materials with customized properties, based on genetic manipulation of immortalized and death-inducible human mesenchymal stromal cells (hMSC), cultured within 3D porous scaffolds under perfusion flow. The strategy allows for robust ECM deposition and subsequent decellularization by deliberate cell-apoptosis induction. As compared to standard production and freeze/thaw treatment, this grants superior preservation of ECM, leading to enhanced bone formation upon implantation in calvarial defects. Tunability of ECM composition and function is exemplified by modification of the cell line to overexpress vascular endothelial growth factor alpha (VEGF), which results in selective ECM enrichment and superior vasculature recruitment in an ectopic implantation model. hMSC lines culture under perfusion-flow is pivotal to achieve uniform scaffold decoration with ECM and to streamline the different engineering/decellularization phases in a single environmental chamber. The findings outline the paradigm of combining suitable cell lines and bioreactor systems for generating ECM-based off-the-shelf materials, with custom set of signals designed to activate endogenous regenerative processes.The biological functionality of scaffold materials can be enhanced and customized by decoration with cell-laid extracellular matrix (ECM). As proof-of-principle of the concept, a death-inducible mesenchymal stromal cell line (MSOD), or its counterpart overexpressing VEGF, are cultured under perfusion flow and induced to apoptosis. The resulting decellularized, customized ECM grafts are used to regenerate bone tissue or to enhance vascularization.
      PubDate: 2017-01-11T05:35:53.670099-05:
      DOI: 10.1002/adfm.201605486
       
  • Embedding Perovskite Nanocrystals into a Polymer Matrix for Tunable
           Luminescence Probes in Cell Imaging
    • Authors: Haihua Zhang; Xu Wang, Qing Liao, Zhenzhen Xu, Haiyang Li, Lemin Zheng, Hongbing Fu
      Abstract: Lead halide perovskite nanocrystals (NCs) with bright luminescence and broad spectral tunability are good candidates as smart probes for bioimaging, but suffer from hydrolysis even when exposed to atmosphere moisture. In this paper, a strategy is demonstrated by embedding CsPbX3 (X = Cl, Br, I) NCs into microhemispheres (MHSs) of polystyrene matrix to prepare “water-resistant” NCs@MHSs hybrids as multicolor multiplexed optical coding agents. First, a facile room-temperature solution self-assembly approach to highly luminescent colloidal CsPbX3 NCs is developed by injecting a stock solution of CsX⋅PbX2 in N,N-dimethylformamide into dichloromethane. Polyvinyl pyrrolidone (PVP) is chosen as the capping ligand, which is physically adsorbed and wrapped on the surface of perovskite NCs to form a protective layer. The PVP protective layer not only leads to composition-tunable CsPbX3 NCs with high quantum yields and narrow emission linewidths of 12–34 nm but also acts as an interfacial layer, making perovskite NCs compatible with polystyrene polymers and facilitating the next step to embed CsPbX3 NCs into polymer MHSs. CsPbX3 NCs@MHSs are demonstrated as multicolor luminescence probes in live cells with high stability and nontoxicity. Using ten intensity levels and seven-color NCs@MHSs that show non-overlapping spectra, it will be possible to individually tag about ten million cells.A strategy to overcome the inherent vulnerability of perovskites to water is demonstrated by embedding CsPbX3 nanocrystals (NCs) into microhemispheres (MHSs) of polystyrene matrix to prepare “water-resistant” NCs@MHSs hybrids. NCs@MHSs are demonstrated as multicolor luminescence probes in live cells with high stability and nontoxicity. Using ten intensity levels and seven-color NCs@MHSs, it will be possible to individually tag about ten million cells.
      PubDate: 2017-01-11T05:15:27.067465-05:
      DOI: 10.1002/adfm.201604382
       
  • Enzymatic Biodegradability of Pristine and Functionalized Transition Metal
           Dichalcogenide MoS2 Nanosheets
    • Authors: Rajendra Kurapati; Laura Muzi, Aritz Perez Ruiz de Garibay, Julie Russier, Damien Voiry, Isabella A. Vacchi, Manish Chhowalla, Alberto Bianco
      Abstract: 2D transition metal dichalcogenide MoS2 nanosheets are increasingly attracting interests due to their promising applications in materials science and biomedicine. However, their biocompatibility and their biodegradability have not been thoroughly studied yet. Here, the biodegradability of exfoliated pristine and covalently functionalized MoS2 (f-MoS2) is investigated. First, biodegradability of these nanomaterials is evaluated using plant horseradish peroxidase and human myeloperoxidase. The results reveal that the enzymatic degradability rate of MoS2 and f-MoS2 is slower than in the case of the simple treatment with H2O2 alone. In parallel, high biocompatibility of both pristine and f-MoS2 nanosheets is found up to 100 µg mL−1 in both cell lines (HeLa and Raw264.7) and primary immune cells. In addition, no immune cell activation and minimal pro-inflammatory cytokine release are observed in RAW264.7 and human monocyte-derived macrophages, suggesting a negligible cellular impact of such materials. Furthermore, the effects of degraded MoS2 and partially degraded f-MoS2 products on cell viability and activation are studied in cancer and immune cells. A certain cytotoxicity is measured at the highest concentrations. Finally, to prove that the cellular impact is due to cell uptake, the internalization of both pristine and functionalized MoS2 in cancer and primary immune cells is assessed.Biodegradation of pristine and covalently functionalized MoS2 by peroxidases in the presence of H2O2 is reported. A faster degradation compared to peroxidase treatment is observed without enzymes using biologically relevant concentrations of H2O2. Importantly, covalent functionalization of MoS2 alters the degradation profile of this type of nanomaterials, opening interesting perspectives in the design of new biomedical tools.
      PubDate: 2017-01-09T08:31:32.641106-05:
      DOI: 10.1002/adfm.201605176
       
  • Cobalt Assisted Synthesis of IrCu Hollow Octahedral Nanocages as Highly
           Active Electrocatalysts toward Oxygen Evolution Reaction
    • Authors: Taehyun Kwon; Hyeyoun Hwang, Young Jin Sa, Jongsik Park, Hionsuck Baik, Sang Hoon Joo, Kwangyeol Lee
      Abstract: Development of oxygen evolution reaction (OER) catalysts with reduced precious metal content while enhancing catalytic performance has been of pivotal importance in cost-effective design of acid polymer electrolyte membrane water electrolyzers. Hollow multimetallic nanostructures with well-defined facets are ideally suited for saving the usage of expensive precious metals as well as boosting catalytic performances; however, Ir-based hollow nanocatalysts have rarely been reported. Here, a very simple synthetic scheme is reported for the preparation of hollow octahedral nanocages of Co-doped IrCu alloy with readily tunable morphology and size. The Co-doped IrCu octahedral nanocages show excellent electrocatalytic activity and long-term durability for OER in acidic media. Notably, their OER activity represents one of the best performances among Ir-based acidic OER catalysts.Novel facet-controlled Co-doped IrCu octahedral hollow nanocages exhibit excellent electrocatalytic activity and durability toward the oxygen evolution reaction in acidic conditions.
      PubDate: 2017-01-09T08:30:55.350544-05:
      DOI: 10.1002/adfm.201604688
       
  • Toward Sensitive Room-Temperature Broadband Detection from Infrared to
           Terahertz with Antenna-Integrated Black Phosphorus Photoconductor
    • Authors: Lin Wang; Changlong Liu, Xiaoshuang Chen, Jing Zhou, Weida Hu, Xiaofang Wang, Jinhua Li, Weiwei Tang, Anqi Yu, Shao-Wei Wang, Wei Lu
      Abstract: Graphene-like two-dimensional materials (graphene, transition-metal dichalcogenides (TMDCs)) have received extraordinary attention owing to their rich physics and potential applications in building nanoelectronic and nanophotonic devices. Recent works have concentrated on increasing the responsivity and extending the operation range to longer wavelengths. However, the weak absorption of gapless graphene, and the large bandgap (>1 eV) and low mobility in TMDCs have limited their spectral usage to only a narrow range in the visible spectrum. In this work, we demonstrate for the first time a high-performance, antenna-integrated, black phosphorus (BP)-based photoconductor with ultra-broadband detection from the infrared to terahertz frequencies. The good trade-off between the moderate bandgap and good mobility results in a broad spectral absorption that is superior to that of graphene. Different photoconductive mechanisms, such as photothermoelectric (PTE), bolometric, and electron–hole generation can be distinguished depending on the device geometry, incident wavelength, and power. Especially, the photoconductive response remains highly efficient, even when the photon energy is extended to the terahertz (THz) band at room temperature, which is driven by the thermoelectric-induced well. The proposed photodetectors have a superior performance with an excellent sensitivity of over 300 V W−1, low noise equivalent power (NEP) (smaller than 1 nW Hz−0.5 (10 pW Hz−0.5) with respect to the incident (absorbed) power), and fast response, all of which play key roles in multispectral biological imaging, remote sensing, and optical communications.A highly efficient room-temperature black phosphorus (BP) detector is shown that can operate from the infrared to the terahertz bands. The moderate bandgap and high mobility of black phosphorus make it a good candidate for both infrared and terahertz detections. Different detection principles are reported for the antenna-coupled BP detector, which is based on the photoconductive effect transiting from the interband electron–hole relaxations to intraband wave excitations.
      PubDate: 2017-01-09T08:30:50.07365-05:0
      DOI: 10.1002/adfm.201604414
       
  • Photoinduced Tetrazole-Based Functionalization of Off-Stoichiometric
           Clickable Microparticles
    • Authors: Chen Wang; Markus M. Zieger, Alexander Schenzel, Martin Wegener, Johannes Willenbacher, Christopher Barner-Kowollik, Christopher N. Bowman
      Abstract: We report the preparation of tetrazole-containing step-growth microparticles and the subsequent use of photoinduced nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) reactions on the particles with spatiotemporal control. Microparticles with an average diameter of 4.1 µm and with inherent tetrazole-ene dual functionality are prepared by a one-pot off-stoichiometric thiol-Michael addition dispersion polymerization. The NITEC reaction is performed efficiently in the solid phase by UV irradiation, leading to the formation of fluorescent pyrozoline adducts, with an estimated quantum yield of 0.7. Particle concentration-independent reaction kinetics are observed and full conversion is reached within 10 min of UV exposure at an intensity of 8 mW cm−2. Temporal control is demonstrated with either UV or rooftop sunlight irradiation of variable duration. By using two-photon writing with a laser centered around 700 nm wavelength, spatial control is demonstrated with micrometer-scale resolution via surface patterning of the microparticles. Further, microparticles with exclusive tetrazole functionality are prepared by a one-pot, two-step thiol-Michael addition dispersion polymerization. The NITEC reaction between tetrazole-functional particles and acrylates in solution is examined at various tetrazole/alkene molar ratios, and a 10:1 excess of alkenes in solution is found necessary for efficient functionalization.We report the preparation of tetrazole-containing step-growth microparticles and the subsequent use of photoinduced nitrile imine-mediated tetrazole-ene cycloaddition reactions on the particles with spatiotemporal control.
      PubDate: 2017-01-06T08:30:34.083959-05:
      DOI: 10.1002/adfm.201605317
       
  • Kirigami/Origami-Based Soft Deployable Reflector for Optical Beam Steering
    • Authors: Wei Wang; Chenzhe Li, Hugo Rodrigue, Fengpei Yuan, Min-Woo Han, Maenghyo Cho, Sung-Hoon Ahn
      Abstract: The beam steering mechanism has been a key element for various applications ranging from sensing and imaging to solar tracking systems. However, conventional beam steering systems are bulky and complex and present significant challenges for scaling up. This work introduces the use of soft deployable reflectors combining a soft deployable structure with simple kirigami/origami reflective films. This structure can be used as a macroscale beam steering mechanism that is both simple and compact. This work first develops a soft deployable structure that is easily scalable by patterning of soft linear actuators. This soft deployable structure is capable of increasing its height several folds by expanding in a continuous and controllable manner, which can be used as a frame to deform the linearly stretchable kirigami/origami structures integrated into the structure. Experiments on the reflective capability of the reflectors are conducted and show a good fit to the modeling results. The proposed principles for deployment and for beam steering can be used to realize novel active beam steering devices, highlighting the use of soft robotic principles to produce scalable morphing structures.Soft deployable reflectors combining a soft deployable structure with simple kirigami/origami reflective films used for dynamic beam steering are presented in this work. This structure can self-deploy by expanding its height several folds. Origami/kirigami reflectors, essentially mirrors with slits, are placed in hollow pockets of the soft deployable structure whose large deformation changes the reflection angle of the reflectors.
      PubDate: 2017-01-05T04:26:12.443096-05:
      DOI: 10.1002/adfm.201604214
       
  • Long Minority-Carrier Diffusion Length and Low Surface-Recombination
           
    • Authors: Bo Wu; Yuanyuan Zhou, Guichuan Xing, Qiang Xu, Hector F. Garces, Ankur Solanki, Teck Wee Goh, Nitin P. Padture, Tze Chien Sum
      Abstract: Sn-based perovskites are promising Pb-free photovoltaic materials with an ideal 1.3 eV bandgap. However, to date, Sn-based thin film perovskite solar cells have yielded relatively low power conversion efficiencies (PCEs). This is traced to their poor photophysical properties (i.e., short diffusion lengths (
      PubDate: 2017-01-05T04:25:39.889513-05:
      DOI: 10.1002/adfm.201604818
       
  • Interface Engineered WxC@WS2 Nanostructure for Enhanced Hydrogen Evolution
           Catalysis
    • Authors: Fengmei Wang; Peng He, Yuanchang Li, Tofik Ahmed Shifa, Ya Deng, Kaili Liu, Qisheng Wang, Feng Wang, Yao Wen, Zhenxing Wang, Xueying Zhan, Lianfeng Sun, Jun He
      Abstract: For increasing scalability and reducing cost, transition metal dichalcogenides-based electrocatalysts presently have been proposed as substitutes for noble metals to generate hydrogen, but these alternatives usually suffer from inferior performance. Here, a Ravenala leaf-like WxC@WS2 heterostructure is grown via carbonizing WS2 nanotubes, whose outer walls being partially unzipped along with the Wx C “leaf-valves” attached to the inner tubes during the carbonization process. This heterostructure exhibits a catalytic activity for hydrogen evolution reaction with low overpotential of 146 mV at 10 mA cm−2 and Tafel slope of 61 mV per decade, outperforming the performance of WS2 nanotubes and WxC counterparts under the same condition. Density functional theory calculations are performed to unravel the underlying mechanism, revealing that the charge distribution between WxC and WS2 plays a key role for promoting H atom adsorption and desorption kinetics simultaneously. This work not only provides a potential low-cost alternative for hydrogen generation but should be taken as a guide to optimize the catalyst structure and composition.Here, a Ravenala leaf-like WxC@WS2 heterostructure with WxC “leaf-valves” attached to the inner WS2 tubes is grown. Its catalytic activity for hydrogen evolution reaction outperforms that of WS2 and WxC counterparts under the same condition. Theoretical calculations reveal the charge distribution at the interface between WxC and WS2 plays a key role for promoting H atom adsorption and desorption kinetics simultaneously.
      PubDate: 2017-01-05T04:25:32.951465-05:
      DOI: 10.1002/adfm.201605802
       
  • Conjugation-Induced Thermally Activated Delayed Fluorescence (TADF): From
           Conventional Non-TADF Units to TADF-Active Polymers
    • Authors: Qiang Wei; Paul Kleine, Yevhen Karpov, Xianping Qiu, Hartmut Komber, Karin Sahre, Anton Kiriy, Ramunas Lygaitis, Simone Lenk, Sebastian Reineke, Brigitte Voit
      Abstract: Thermally activated delayed fluorescence (TADF)-type compounds have great potential as emitter molecules in organic light-emitting diodes, allowing for electrofluorescence with 100% internal quantum efficiency. In small molecules, TADF is achieved through the formation of intramolecular charge-transfer states. The only design limitation is the requirement that donor and acceptor entities spatially decouple the highest occupied and lowest unoccupied molecular orbitals, respectively, to minimize exchange splitting. The development of polymeric TADF emitters, on the contrary, has seen comparably small progress and those are typically built up from monomeric units that show promising TADF properties in small molecule studies beforehand. By contrast, herein, a way to achieve TADF properties in cyclic oligomers and polymers composed of non-TADF building blocks is shown. Due to a strongly decreased energy splitting of the polymer with respect to the individual repeating unit between the lowest singlet and triplet excited state (ΔEST) and a sufficiently high radiative decay rate kSr, a highly efficient TADF polymer with up to 71% photoluminescence quantum yield is obtained. For the first time, an encouraging method is provided for producing highly efficient TADF oligomers and polymers from solely non-TADF units via induced conjugation, opening a new design strategy exclusive for polymers.A thermally activated delayed fluorescence (TADF) π-conjugated cyclic polymer composed of non-TADF building blocks is developed. Conjugation-induced highest occupied molecular orbital destabilization leads to a decreased singlet–triplet splitting and efficient TADF in the polymer, while the repeating unit itself shows only inefficient phosphorescence. This conjugation-induced TADF concept represents a novel molecular design rule particularly for solution-processable polymeric materials.
      PubDate: 2017-01-04T08:55:44.698321-05:
      DOI: 10.1002/adfm.201605051
       
  • Phase Transition Induced Synthesis of Layered/Spinel Heterostructure with
           Enhanced Electrochemical Properties
    • Authors: Yi Pei; Cheng-Yan Xu, Yu-Chen Xiao, Qing Chen, Bin Huang, Bin Li, Shuang Li, Liang Zhen, Guozhong Cao
      Abstract: A one-step synthesis of Li-rich layered materials with layered/spinel heterostructure has been systematically investigated. The composites are synthesized by a polyol method followed with an annealing process at 500–900 °C for 12 h. A spinel to layer phase transition is considered to take place during the heat treatment, and the samples obtained at different temperatures show diverse phase compositions. An “Li-rich spinel phase decomposition” phase transition mechanism is proposed to explain the formation of such a heterostructure. The electrochemical properties of the heterostructure are found to be associated with the ratio of spinel to layer phases, the leach out of rock salt phase, and the change of crystallinity and particle size. Product with improved cyclic and rate performance is achieved by annealing at 700 °C for 12 h, with a discharge capacity of 214 mA h g−1 remaining at 0.2 C after 60 cycles and discharge capacity of about 200 mA h g−1 at 1 C.Li-rich layered materials with layered/spinel heterostructure are prepared through a novel polyol method. With an “Li-rich spinel phase decomposition” phase transition mechanism, the content of LLO is controllable and the products with moderate content of spinel phase demonstrate superior electrochemical performances with a discharge capacity of about 200 mA h g−1 at 1 C.
      PubDate: 2017-01-04T08:55:31.055397-05:
      DOI: 10.1002/adfm.201604349
       
  • Al-Doped Black Phosphorus p–n Homojunction Diode for High
           Performance Photovoltaic
    • Authors: Yuanda Liu; Yongqing Cai, Gang Zhang, Yong-Wei Zhang, Kah-Wee Ang
      Abstract: 2D layered materials based p–n junctions are fundamental building block for enabling new functional device applications with high efficiency. However, due to the lack of controllable doping technique, state-of-the-art 2D p–n junctions are predominantly made of van der Waals heterostructures or electrostatic gated junctions. Here, the authors report the demonstration of a spatially controlled aluminum doping technique that enables a p–n homojunction diode to be realized within a single 2D black phosphorus nanosheet for high performance photovoltaic application. The diode achieves a near-unity ideality factor of 1.001 along with an on/off ratio of ≈5.6 × 103 at a low bias of 2 V, allowing for low-power dynamic current rectification without signal decay or overshoot. When operated under a photovoltaic regime, the diode's dark current can be significantly suppressed. The presence of a built-in electric field additionally gives rise to temporal short-circuit current and open-circuit voltage under zero external bias, indicative of its enriched functionalities for self-powered photovoltaic and high signal-to-noise photodetection applications.2D p–n junction is a fundamental building block for nanoelectronics devices, which has been predominantly realized using van der Waals heterostructures or electrostatic-gated junctions due to the lack of controllable doping techniques. Here, near-ideal black phosphorus p–n homojunction diodes are achieved by novel and facile Al-atom doping, paving the way toward high performance photovoltaic applications.
      PubDate: 2017-01-03T09:15:56.104535-05:
      DOI: 10.1002/adfm.201604638
       
  • Atomic Insights into the Enhanced Surface Stability in High Voltage
           Cathode Materials by Ultrathin Coating
    • Authors: Xin Fang; Feng Lin, Dennis Nordlund, Matthew Mecklenburg, Mingyuan Ge, Jiepeng Rong, Anyi Zhang, Chenfei Shen, Yihang Liu, Yu Cao, Marca M. Doeff, Chongwu Zhou
      Abstract: Surface properties of electrode materials play a critical role in the function of batteries. Therefore, surface modifications, such as coatings, have been widely used to improve battery performance. Understanding how these coatings function to improve battery performance is crucial for both scientific research and applications. In this study the electrochemical performance of coated and uncoated LiNi0.5Mn1.5O4 (LNMO) electrodes is correlated with ensemble-averaged soft X-ray absorption spectroscopy (XAS) and spatially resolved scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) to illustrate the mechanism of how ultrathin layer Al2O3 coatings improve the cycle life of LiNi0.5Mn1.5O4. Mn2+ evolution on the surface is clearly observed in the uncoated sample, which results from the reaction between the electrolytic solution and the surfaces of LiNi0.5Mn1.5O4 particles, and also possibly atomic structure reconstructions and oxygen loss from the surface region in LiNi0.5Mn1.5O4. The coating effectively suppresses Mn2+ evolution and improves the battery performance by decelerating the impedance buildup from the surface passivation. This study demonstrates the importance of combining ensemble-averaged techniques (e.g., XAS) with localized techniques (e.g., STEM-EELS), as the latter may yield unrepresentative information due to the limited number of studied particles, and sheds light on the design of future coating processes and materials.Atomic layer deposition was employed as an ultrathin coating on LiNi0.5Mn1.5O4, a cathode in lithium-ion batteries. X-ray absorption spectroscopy and scanning transmission electron microscopy-electron energy loss spectroscopy were used to characterize both pristine and coated materials before and after cycling. The results show that the coating suppressed Mn2+ formation, decelarating impedance buildup from surface passivation and improving cycling behavior.
      PubDate: 2017-01-03T09:15:35.010825-05:
      DOI: 10.1002/adfm.201602873
       
  • Toroidal Protein Adaptor Assembles Ferrimagnetic Nanoparticle Fibers with
           Constructive Magnetic Coupling
    • Authors: Tuan Anh Pham; Andreas Schreiber, Stefan M. Schiller, Helmut Cölfen
      Abstract: Inspired by nature, the synthesis of biohybrid nanocomposites containing inorganic nanoparticles (NPs) and biopolymers such as DNA and peptides as templates offers great potential for a wide range of applications. Using selective recognition schemes of 3D protein spaces for the assembly of magnetic nanocrystals is a challenge with great promise in the field of biomedicine and magnetic data storage. Here we apply the toroidal protein Hcp1 as an interparticle connector for the directed molecular assembly and ferrimagnetic coupling of biohybrid cobalt ferrite NP wires. The resulting biohybrid NP composites show bundles of nanofibers ranging from nano- to the microscale in length verified by TEM, EDX analysis and focused ion beam cut. Their magnetic characterization reveals an increase of the coercive field (+12%) reaching values of high-end Nd2Fe14B bulk magnets, enhanced saturation (+28%) and remanence magnetization (+38%) at 2 K compared to NPs lacking the protein connector. Thus, the combination of the nanoscale alignment of magnetic NPs with the molecular precision of the protein connectors leads to constructive addition of the magnetization reversal energy. This approach can be used to control magnetic properties for the design of materials with enhanced coercivity applicable for magnetic data storage, hyperthermia and theranostics.Applying the toroidal protein Hcp1 as an interparticle connector leads to directed molecular assembly and ferrimagnetic coupling of cobalt ferrite nanoparticles. Assembled biohybrid nanofibers range from the nano- to the microscale. Their magnetic characterization reveals enhanced saturation (+28%) and remanence magnetization (+38%) and an increase in the coercive field (+12%) reaching values of high-end Nd2Fe14B bulk magnets at 2 K.
      PubDate: 2017-01-03T01:52:23.7521-05:00
      DOI: 10.1002/adfm.201604532
       
  • Electrowetting-Induced Morphological Evolution of Metal-Organic Inverse
           Opals toward a Water-Lithography Approach
    • Authors: Junchao Liu; Lun Wan, Manbo Zhang, Kejian Jiang, Kai Song, Jingxia Wang, Tomiki Ikeda, Lei Jiang
      Abstract: This paper presents a unique morphological evolution of metal-organic inverse opals (Pb(NO3)2-poly(St-MMA-AA)) subjected to an electrowetting process. The morphology of the building blocks changes from interconnected pores to separated hollow spheres during the electrowetting process, accompanied by an unusual blue-shift of the stopband position and the decreased wettability of the film. This morphology evolution is attributed to the simultaneous collapse/reconstruction of the metal-organic frame owing to the partial dissolution of the metal salt and the interfacial assembly of the metal-organic coordination around the skeleton. The adjustable morphology can be developed as a novel and simple water-lithography approach for the creation of the photonic crystal pattern.A unique morphological evolution is demonstrated for metal-organic inverse opals during an electrowetting process. The building blocks of inverse opals change from the interconnected pore to the separated hollow sphere with respect to electrowetting time, accompanied by a blue-shift in the reflection bands and the decreased wettability of the film, which provides a facile strategy for the water-lithography technique.
      PubDate: 2017-01-03T01:52:10.118142-05:
      DOI: 10.1002/adfm.201605221
       
  • Facile Doping and Work-Function Modification of Few-Layer Graphene Using
           Molecular Oxidants and Reductants
    • Authors: Ahmed E. Mansour; Marcel M. Said, Sukumar Dey, Hanlin Hu, Siyuan Zhang, Rahim Munir, Yadong Zhang, Karttikay Moudgil, Stephen Barlow, Seth R. Marder, Aram Amassian
      Abstract: Doping of graphene is a viable route toward enhancing its electrical conductivity and modulating its work function for a wide range of technological applications. In this work, the authors demonstrate facile, solution-based, noncovalent surface doping of few-layer graphene (FLG) using a series of molecular metal-organic and organic species of varying n- and p-type doping strengths. In doing so, the authors tune the electronic, optical, and transport properties of FLG. The authors modulate the work function of graphene over a range of 2.4 eV (from 2.9 to 5.3 eV)—unprecedented for solution-based doping—via surface electron transfer. A substantial improvement of the conductivity of FLG is attributed to increasing carrier density, slightly offset by a minor reduction of mobility via Coulomb scattering. The mobility of single layer graphene has been reported to decrease significantly more via similar surface doping than FLG, which has the ability to screen buried layers. The dopant dosage influences the properties of FLG and reveals an optimal window of dopant coverage for the best transport properties, wherein dopant molecules aggregate into small and isolated clusters on the surface of FLG. This study shows how soluble molecular dopants can easily and effectively tune the work function and improve the optoelectronic properties of graphene.Solution-based noncovalent doping of few-layer graphene using novel metal-organic and organic molecules is demonstrated to enhance the conductivity and modulate the work function over a range of 2.4 eV with marginal reduction of mobility. The effects of dopant strength and coverage are shown to play a crucial role in the optimization of the performance of few-layer graphene as a transparent conductive electrode.
      PubDate: 2017-01-03T01:52:05.038416-05:
      DOI: 10.1002/adfm.201602004
       
  • Stabilized Octahedral Frameworks in Layered Double Hydroxides by
           Solid-Solution Mixing of Transition Metals
    • Authors: Ji Hoon Lee; Hyeon Jeong Lee, Soo Yeon Lim, Keun Hwa Chae, Sung Hyeon Park, Kyung Yoon Chung, Erhan Deniz, Jang Wook Choi
      Abstract: Pseudocapacitors have received considerable attention, as they possess advantages of both rechargeable batteries and electric double layer capacitors. Among various active materials for pseudocapacitors, α-layered double hydroxides (α-TM(OH)2, TM = transition metal) are promising due to their high specific capacities. Yet, irreversible α-to-β phase transitions of α-TM(OH)2 hinder their long-term cyclability, particularly when the TM is nickel. Here, it is reported that binary TM ion mixing can overcome the limited cycle lives of α-TM(OH)2 by stabilizing the octahedral frameworks of α-TM(OH)2. In particular, an α-TM(OH)2 with equal amounts of nickel and cobalt exhibits long-term capacity retention (89.0% after 2000 cycles) and specific capacity (206 mA h g−1), which are better than those of individual TM counterparts. A series of analyses reveals that the improved performances originate from the synergistic effects between the TM ions; the preferred trivalent state of cobalt ions stabilizes the octahedral framework by accommodating the detrimental Jahn–Teller distortion of Ni3+. The stabilized framework also widens the redox swing range of the nickel up to 4+, thus, increasing the specific capacity of the corresponding α-TM(OH)2. This study indicates that proper mixing of TMs is a prolific approach in enhancing the vital properties of α-TM(OH)2, a promising family of pseudocapacitor materials.An α-layered double hydroxide with equal amounts of nickel and cobalt ions exhibits high performances in specific capacity (206 mA h g−1) and cycle life (89.0% after 2000 cycles) as a pseudocapacitor electrode material. These electrochemical properties are attributed to the synergistic interplay of d-electrons of both transition metal ions upon their solid-solution mixing.
      PubDate: 2016-12-29T10:55:57.009666-05:
      DOI: 10.1002/adfm.201605225
       
 
 
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