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  Subjects -> CHEMISTRY (Total: 814 journals)
    - ANALYTICAL CHEMISTRY (49 journals)
    - CHEMISTRY (566 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (46 journals)
    - PHYSICAL CHEMISTRY (65 journals)

CHEMISTRY (566 journals)                  1 2 3 4 5 6 | Last

2D Materials     Hybrid Journal   (Followers: 4)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 31)
ACS Catalysis     Full-text available via subscription   (Followers: 25)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 13)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 8)
ACS Macro Letters     Full-text available via subscription   (Followers: 20)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 25)
ACS Nano     Full-text available via subscription   (Followers: 355)
ACS Photonics     Full-text available via subscription   (Followers: 6)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 10)
Acta Chemica Iasi     Open Access  
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 6)
Acta Chromatographica     Full-text available via subscription   (Followers: 10)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 4)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 5)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 10)
Advanced Functional Materials     Hybrid Journal   (Followers: 38)
Advances in Chemical Engineering and Science     Open Access   (Followers: 23)
Advances in Chemical Science     Open Access   (Followers: 9)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 15)
Advances in Drug Research     Full-text available via subscription   (Followers: 18)
Advances in Enzyme Research     Open Access  
Advances in Fluorine Science     Full-text available via subscription   (Followers: 7)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 13)
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: 9)
Advances in Polymer Science     Hybrid Journal   (Followers: 39)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 10)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 4)
African Journal of Chemical Education     Open Access   (Followers: 1)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 5)
Afrique Science : Revue Internationale des Sciences et Technologie     Open Access   (Followers: 1)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 1)
Alchemy     Open Access   (Followers: 3)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
AMB Express     Open Access  
American Journal of Applied Sciences     Open Access   (Followers: 31)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 213)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 12)
American Journal of Chemistry     Open Access   (Followers: 18)
American Journal of Plant Physiology     Open Access   (Followers: 10)
American Mineralogist     Full-text available via subscription   (Followers: 7)
Analyst     Full-text available via subscription   (Followers: 36)
Angewandte Chemie     Hybrid Journal   (Followers: 18)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 273)
Annales UMCS, Chemia     Open Access   (Followers: 2)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 1)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 2)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 11)
Anti-Infective Agents     Hybrid Journal   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Applied Spectroscopy     Full-text available via subscription   (Followers: 12)
Applied Surface Science     Hybrid Journal   (Followers: 20)
Arabian Journal of Chemistry     Full-text available via subscription   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 4)
Autophagy     Full-text available via subscription   (Followers: 1)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemistry     Full-text available via subscription   (Followers: 261)
Biochemistry Insights     Open Access   (Followers: 4)
Biochemistry Research International     Open Access   (Followers: 4)
BioChip Journal     Hybrid Journal   (Followers: 1)
Bioinorganic Chemistry and Applications     Open Access   (Followers: 4)
Bioinspired Materials     Open Access  
Biointerface Research in Applied Chemistry     Open Access   (Followers: 1)
Biointerphases     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 17)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 5)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 2)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 30)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 24)
Bioorganic Chemistry     Hybrid Journal   (Followers: 5)
Biopolymers     Hybrid Journal   (Followers: 14)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 13)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 3)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 6)
Canadian Mineralogist     Full-text available via subscription   (Followers: 1)
Carbohydrate Research     Hybrid Journal   (Followers: 11)
Carbon     Hybrid Journal   (Followers: 55)
Catalysis for Sustainable Energy     Open Access   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 6)
Catalysis Science and Technology     Free   (Followers: 4)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 7)

        1 2 3 4 5 6 | Last

Journal Cover   Advanced Functional Materials
  [SJR: 4.862]   [H-I: 136]   [40 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  [1606 journals]
  • A Versatile Nanotheranostic Agent for Efficient Dual‐Mode Imaging
           Guided Synergistic Chemo‐Thermal Tumor Therapy
    • Authors: Xiaojun Cai; Xiaoqing Jia, Wei Gao, Kun Zhang, Ming Ma, Shige Wang, Yuanyi Zheng, Jianlin Shi, Hangrong Chen
      Pages: n/a - n/a
      Abstract: The integration of efficient imaging for diagnosis and synergistic tumor therapy into a single‐component nanoplatform is much promising for high efficacy tumor treatment but still in a great challenge. Herein, a smart and versatile nanotheranostic platform based on hollow mesoporous Prussian blue nanoparticles (HMPBs) with perfluoropentane (PFP) and doxorubicin (DOX) inside, has been designed, for the first time, to achieve the distinct in vivo synergistic chemo‐thermal tumor therapy and synchronous diagnosis and monitoring by ultrasound (US)/photoacoustic (PA) dual mode imaging. The prepared HMPBs show excellent photothermal conversion properties with large molar extinction coefficient (≈1.2 × 1011m−1 cm−1) and extremely high photothermal conversion efficiency (41.4%). Such a novel theranostic nanoplatform is expected to overcome the inevitable tumor recurrence and metastasis resulting from the inhomogeneous ablation of single thermal therapy, which will find a promising prospect in the application of noninvasive cancer therapy. A smart and versatile theranostic nanoplatform with single component based on hollow mesoporous Prussian blue nanoparticles is developed for the in vivo highly efficient synergistic chemo‐thermal tumor therapy, guided by synchronous imaging diagnosis and therapy monitoring using ultrasound and photoacoustic dual‐mode imaging for the first time.
      PubDate: 2015-02-27T05:56:57.096286-05:
      DOI: 10.1002/adfm.201403991
       
  • 2D Janus Hybrid Materials of Polymer‐Grafted Carbon
           Nanotube/Graphene Oxide Thin Film as Flexible, Miniature Electric Carpet
    • Authors: Peng Xiao; Changjin Wan, Jincui Gu, Zhenzhong Liu, Yonghong Men, Youju Huang, Jiawei Zhang, Liqiang Zhu, Tao Chen
      Pages: n/a - n/a
      Abstract: Ultrathin, freestanding polymer hybrid film with macroscopic sizes and molecular thicknesses have received significant interest due to their applications as functional devices, microsensors or nanoactuators. Herein, a 2D Janus hybrid of polymer‐grafted carbon nanotubes/graphene oxide (CNTs/GO) thin film is fabricated using microcontact printed CNTs/GO as photo active surface to grow polymer brushes by self‐initiated photografting and photopolymerization selectively from one side of CNTs/GO film. This achieved 2D Janus hybrid materials with grafted polymer layer as insulative carpet and supported CNTs/GO thin film as conductive element have the potential application as flexible and miniature electric carpet for heating micro‐/nano devices locally. A polymeric electrical carpet of 2D Janus hybrid thin film, with grafted polymer layer as insulative carpet and supported carbon materials as conductive element, has the potential application in heating micro‐/nano devices locally.
      PubDate: 2015-02-27T05:56:50.354035-05:
      DOI: 10.1002/adfm.201404624
       
  • Facet‐Level Mechanistic Insights into General Homogeneous Carbon
           Doping for Enhanced Solar‐to‐Hydrogen Conversion
    • Authors: Jie Li; Kun Zhao, Ying Yu, Lizhi Zhang
      Pages: n/a - n/a
      Abstract: Homogeneous doping can boost solar‐to‐hydrogen conversion and therefore attracts great attention. Although a great deal of effort has been made to explore the doping–photoreactivity relationship, the doping mechanisms, especially from the perspective of crystal facets, are seldom explored. In this study, a general homogeneous carbon doping strategy is established and then serves as the doping model for a mechanistic investigation, as encouraged by its versatility in enabling homogeneous incorporation of carbon and improving solar‐to‐hydrogen conversion for typical oxides including TiO2, ZnO, and BiOCl. Using well‐defined BiOCl nanosheets of high {001} or {010} facet exposure, we clarify the homogeneous carbon doping mechanism at the level of crystal facets for the first time. This mechanism involves the initial facet‐dependent adsorption of the dopant precursor, regulated by the surface atomic structures, and the subsequent facet‐dependent diffusion of carbon dopants associated with the facet‐related arrangements of bulk atoms. This results in facet‐dependent carbon doping behavior and a dopant‐concentration‐dependent solar‐to‐hydrogen conversion property of BiOCl nanosheets. These mechanistic insights also suggest that the implantation of the dopant precursor in the shallow lattice of host nanocrystal is vital for the effective homogeneous doping. This new doping model is different from the conventional counterpart based on the organic ligands or gas molecules adsorption onto the surface of host nanocrystals, where surface doping usually occurs. Facet‐level understanding of a general homogeneous carbon doping mechanism is demonstrated. The initial facet‐dependent adsorption of the dopant precursor, regulated by the surface atomic structures, and the subsequent facet‐dependent diffusion of the carbon dopant, associated with the facet‐related arrangements of bulk atoms, are identified as the two key factors to determine the concentration of carbon dopants.
      PubDate: 2015-02-26T11:52:38.796138-05:
      DOI: 10.1002/adfm.201404178
       
  • Microfluidic Spinning of Cell‐Responsive Grooved Microfibers
    • Authors: Xuetao Shi; Serge Ostrovidov, Yihua Zhao, Xiaobin Liang, Motohiro Kasuya, Kazue Kurihara, Ken Nakajima, Hojae Bae, Hongkai Wu, Ali Khademhosseini
      Pages: n/a - n/a
      Abstract: Engineering living tissues that simulate their natural counterparts is a dynamic area of research. Among the various models of biological tissues being developed, fiber‐shaped cellular architectures, which can be used as artificial blood vessels or muscle fibers, have drawn particular attention. However, the fabrication of continuous microfiber substrates for culturing cells is still limited to a restricted number of polymers (e.g., alginate) having easy processability but poor cell–material interaction properties. Moreover, the typical smooth surface of a synthetic fiber does not replicate the micro‐ and nanofeatures observed in vivo, which guide and regulate cell behavior. In this study, a method to fabricate photocrosslinkable cell‐responsive methacrylamide‐modified gelatin (GelMA) fibers with exquisite microstructured surfaces by using a microfluidic device is developed. These hydrogel fibers with microgrooved surfaces efficiently promote cell encapsulation and adhesion. GelMA fibers significantly promote the viability of cells encapsulated in/or grown on the fibers compared with similar grooved alginate fibers used as controls. Importantly, the grooves engraved on the GelMA fibers induce cell alignment. Furthermore, the GelMA fibers exhibit excellent processability and could be wound into various shapes. These microstructured GelMA fibers have great potential as templates for the creation of fiber‐shaped tissues or tissue microstructures. A photocrosslinkable microgrooved methacrylamide‐modified gelatin (GelMA) fiber is produced via the use of a microfluidic device. The combination of the cell supportive properties of GelMA and the topographical cues allows improved cell‐material interactions favoring anisotropic tissue formation. Moreover, the high hydration content and viscoelastic properties of the hydrogel allow the coculturing cell types in and on the fiber.
      PubDate: 2015-02-26T06:59:23.936823-05:
      DOI: 10.1002/adfm.201404531
       
  • Development and Manufacture of Polymer‐based Electrochromic Devices
    • Authors: Jacob Jensen; Markus Hösel, Aubrey L. Dyer, Frederik C. Krebs
      Pages: n/a - n/a
      Abstract: The field of organic electrochromics is reviewed here, with particular focus on how the “electrochromic” as a functional material can be brought from the current level of accurate laboratory synthesis and characterization to the device and application level through a number of suited roll‐to‐roll methods compatible with upscaling and manufacture. The successful approaches to operational devices are presented in detail, as well as areas where future research would have a high impact and accelerate the development such as highly conducting and transparent substrates, electrolytes adapted for multilayer application and morphologically stable conjugated polymers. The materials science of the electrochromic device is reviewed with particular focus on the possible manufacturing routes, the requirements they impose on the materials and the achievable overall device performance. Applications are discussed and the recent progress in realizing solid state flexible devices based on electrochromics and their combination with other advanced devices such as solar cells is reviewed along with an overview of areas where developments would have a large impact.
      PubDate: 2015-02-26T06:58:15.66077-05:0
      DOI: 10.1002/adfm.201403765
       
  • Self‐Doped Conjugated Polymeric Nanoassembly by Simplified Process
           for Optical Cancer Theragnosis
    • Authors: Jeonghun Kim; Eugene Lee, Yoochan Hong, Byeonggwan Kim, Minhee Ku, Dan Heo, Jihye Choi, Jongbeom Na, Jungmok You, Seungjoo Haam, Yong‐Min Huh, Jin‐Suck Suh, Eunkyoung Kim, Jaemoon Yang
      Pages: n/a - n/a
      Abstract: To access smart optical theragnosis for cancer, an easily processable heterocyclic conjugated polymer (poly(sodium3‐((3‐methyl‐3,4‐dihydro‐2H‐thieno[3,4‐b][1,4]dioxepin‐3‐yl)methoxy)propane‐1‐sulfonate), PPDS) nanoassembly is fabricated by a surfactant‐free one‐step process, without the laborious ordinary multicoating process. The conjugated nanoassembly, with a self‐doped structure, provides strong absorbance in the near‐infrared (NIR) range even in a neutral pH medium and exhibits excellent stability (>six months). In addition, the prepared PPDS nanoassembly shows a high photothermal conversion efficiency of 31.4% in organic photothermal nanoparticles. In particular, the PPDS nanoassembly is stably suspended in the biological medium without any additives. Through a simple immobilization with the anti‐CD44 antibody, the prepared biomarker‐targetable PPDS nanoassembly demonstrates specific targeting toward CD44 (expressed in stem‐like cancer cells), allowing NIR absorbance imaging and the efficient targeted photothermal damaging of CD44‐expressing cancer cells, from in vitro 3D mammospheres (similar to the practical structure of tumor in the body) to in vivo xenograft mice tumor models (breast cancer and fibrosarcoma). In this study, the most simplified preparation method is for this organic conjugated polymer‐based nanoassembly by a molecular approach is reported, and demonstrated as a highly promising optical nanoagent for optical cancer theragnosis. A thiophene‐based photothermal (PT) organic nanoprobe is synthesized, with a simplified preparation process not requiring PEGylation or multicoating. The synthesized nanoassembly shows good stability, biocompatibility, and PT properties. The nanoassembly is applied to 3D tumor mammospheres and breast cancer, and shows excellent specific targeting of the CD44‐expressing cancerous cells, near‐infrared (NIR) absorbance imaging in vivo, and effective damaging by NIR light irradiation.
      PubDate: 2015-02-26T06:57:11.80741-05:0
      DOI: 10.1002/adfm.201500076
       
  • Contrast Agent Incorporation into Silicone Enables Real‐Time
           
    • Authors: Michael Loepfe; Christoph M. Schumacher, Cornelia H. Burri, Wendelin J. Stark
      Pages: n/a - n/a
      Abstract: The construction of machines consisting essentially of soft parts is a nascent and multidisciplinary research field between material science, machine engineering, and robotics. Soft silicones represent a promising class of materials for the creation of a vast multitude of biologically inspired entities. In the present work, a new type of mammalian vein‐inspired soft silicone pump is introduced and characterized, which is fabricated by virtual lost‐wax casting of 3D‐printed injection molds. These pumps can be actuated pneumatically or by internal gas combustion and preserve their functionality even after a freezing/unfreezing cycle. The possibility of using medical examination methods such as ultrasonic imaging to directly access flow information inside soft pumps is shown. Based on soda lime glass microspheres, a method is demonstrated to enhance contrast properties during such color online Doppler imaging for a detailed understanding of the inner fluid‐structure interactions. There is a nascent research field on machines that are made essentially from soft materials. A new type of mammalian vein‐inspired soft silicone liquid pump is presented and characterized, that is based on lost‐wax casting of 3D printed injection molds. By functionalizing the material with contrast agents, inner workings can be visualized in real‐time by the use of medical ultrasonography.
      PubDate: 2015-02-25T05:49:55.486435-05:
      DOI: 10.1002/adfm.201404461
       
  • Magnesiothermic Reduction of Thin Films: Towards Semiconducting Chiral
           Nematic Mesoporous Silicon Carbide and Silicon Structures
    • Authors: Thanh‐Dinh Nguyen; Joel A. Kelly, Wadood Y. Hamad, Mark J. MacLachlan
      Pages: n/a - n/a
      Abstract: There is a growing demand for new methods to prepare porous Si‐based materials for applications in optoelectronic and microelectronic devices. In this work, the preparation of SiC and Si from magnesiothermic reduction of chiral nematic SiO2/C composites and mesoporous SiO2, respectively, is reported. The SiO2/C composites are prepared by cocondensing SiO2 with cellulose nanocrystals (CNCs) followed by pyrolysis. The magnesiothermic reduction of the composites produces SiC after prolonged solid‐state reaction, with mixed MgC2/SiC intermediates. Iridescent mesoporous tetragonal MgC2/SiC structures that retain the long‐range twisted organization of the starting composites transform to mesoporous cubic SiC with a chiral nematic hierarchical structure, but with some loss of order. On the other hand, the magnesiothermic reduction of the chiral nematic mesoporous SiO2 templated from CNCs affords mesoporous Si materials with a layered hierarchical structure. The structural properties and the conductivity of the products, as well as the reaction pathways by analysis of the materials at intermediate stages, are investigated. These experimental results show that the magnesiothermic reduction is a promising way to obtain new porous semiconducting materials with chiral nematic structures. Magnesiothermic reduction of chiral nematic silica/carbon and mesoporous silica films templated by cellulose nanocrystals is investigated. The reduction process of silica/carbon forms MgC2/SiC intermediates and then transforms to chiral nematic mesoporous SiC, while silica produces mesoporous Si with a layered hierarchical structure. These novel semiconducting materials are available as film replicas and may be useful for developing thin film sensors.
      PubDate: 2015-02-25T05:48:53.379574-05:
      DOI: 10.1002/adfm.201404304
       
  • White Light‐Emitting Diode From Sb‐Doped p‐ZnO Nanowire
           Arrays/n‐GaN Film
    • Authors: Xiaoliang Ren; Xianghui Zhang, Nishuang Liu, Li Wen, Longwei Ding, Zongwei Ma, Jun Su, Luying Li, Junbo Han, Yihua Gao
      Pages: n/a - n/a
      Abstract: A whole interfacial transition of electrons from conduction bands of n‐type material to the acceptor levels of p‐type material makes the energy band engineering successful. It tunes intrinsic ZnO UV emission to UV‐free and warm white light‐emitting diode (W‐LED) emission with color coordinates around (0.418, 0.429) at the bias of 8–15.5 V. The W‐LED is fabricated based on antimony (Sb) doped p‐ZnO nanowire arrays/Si doped n‐GaN film heterojunction structure through one‐step chemical vapor deposition with quenching process. Element analysis shows that the doping concentration of Sb is ≈1.0%. The I–V test exhibits the formation of p‐type ZnO nanowires, and the temperature‐dependent photoluminescence measurement down to 4.65 K confirms the formation of deep levels and shallow acceptor levels after Sb‐doping. The intrinsic UV emission of ZnO at room temperature is cut off in electroluminescence emission at a bias of 4–15.5 V. The UV‐free and warm W‐LED have great potential application in green lights program, especially in eye‐protected lamp and display since television, computer, smart phone, and mobile digital equipment are widely and heavily used in modern human life, as more than 3000 h per year. A whole interfacial transition of electrons from conduction bands of n‐type GaN film to the acceptor levels of p‐type antimony (Sb) doped ZnO nanowire arrays makes the energy band engineering successful. It tunes intrinsic ZnO UV emission to UV‐free and warm white light‐emitting diode (W‐LED) emission with color coordinates around (0.418, 0.429) at the bias of 8–15.5 V.
      PubDate: 2015-02-25T05:48:02.458887-05:
      DOI: 10.1002/adfm.201404316
       
  • Remotely Controlled Red Blood Cell Carriers for Cancer Targeting and
           Near‐Infrared Light‐Triggered Drug Release in Combined
           Photothermal–Chemotherapy
    • Authors: Xiaoqi Sun; Chao Wang, Min Gao, Aiyan Hu, Zhuang Liu
      Pages: n/a - n/a
      Abstract: Red blood cells (RBCs), the “innate carriers” in blood vessels, are gifted with many unique advantages in drug transportation over synthetic drug delivery systems (DDSs). Herein, a tumor angiogenesis targeting, light stimulus‐responsive, RBC‐based DDS is developed by incorporating various functional components within the RBC platform. An albumin bound near‐infrared (NIR) dye, together with a chemotherapy drug doxorubicin, is encapsulated inside RBCs, the surfaces of which are modified with a targeting peptide to allow cancer targeting. Under stimulation by an external NIR laser, the membrane of the RBCs would be destroyed by the light‐induced photothermal heating, resulting in effective drug release. As a proof of principle, RBC‐based cancer cell targeted drug delivery and light‐controlled drug release is demonstrated in vitro, achieving a marked synergistic therapeutic effect through the combined photothermal–chemotherapy. This work presents a novel design of smart RBC carriers, which are inherently biocompatible, promising for targeted combination therapy of cancer. A tumor angiogenesis targeting red blood cell (RBC)‐based drug delivery system is successfully fabricated by incorporating various functional components within the RBC platform, and is responsive to near‐infrared light stimulus. As a proof of principle, RBC‐based cancer cell targeted drug delivery and light‐controlled drug release is demonstrated in vitro, achieving a marked synergistic therapeutic effect through the combined photothermal–chemotherapy.
      PubDate: 2015-02-25T05:46:41.626855-05:
      DOI: 10.1002/adfm.201500061
       
  • TiO2@Layered Double Hydroxide Core–Shell Nanospheres with Largely
           Enhanced Photocatalytic Activity Toward O2 Generation
    • Authors: Yibo Dou; Shitong Zhang, Ting Pan, Simin Xu, Awu Zhou, Min Pu, Hong Yan, Jingbin Han, Min Wei, David G. Evans, Xue Duan
      Pages: n/a - n/a
      Abstract: TiO2@CoAl‐layered double hydroxide (LDH) core–shell nanospheres are fabricated via hydrothermal synthesis of TiO2 hollow nanospheres followed by in situ growth of CoAl‐LDH shell, which exhibit an extraordinarily high photocatalytic activity toward oxygen evolution from water oxidation. The O2 generation rates of 2.34 and 2.24 mmol h−1 g−1 are achieved under full sunlight (>200 nm) and visible light (>420 nm), respectively, which are among the highest photocatalytic activities for oxygen production to date. The reason is attributed to the desirable incorporation of visible‐ light‐active LDH shell with UV light‐responsive TiO2 core for promoted solar energy utilization. Most importantly, the combined experimental results and computational simulations reveal that the strong donor–acceptor coupling and suitable band matching between TiO2 core and LDH shell facilitate the separation of photoinduced electron‐hole pairs, accounting for the highly efficient photocatalytic performance. Therefore, this work provides a facile and cost‐effective strategy for the design and fabrication of hierarchical semiconductor materials, which can be applied as photocatalyst toward water splitting and solar energy conversion. TiO2@CoAl‐layered double hydroxide (LDH) core–shell nanospheres are fabricated via hydrothermal synthesis of TiO2 hollow nanospheres followed by in situ growth of CoAl‐LDH shell, which exhibit an extraordinarily high photocatalytic activity toward oxygen evolution from water oxidation. A strong donor–acceptor coupling and suitable band matching between TiO2 core and LDH shell facilitate the separation of photoinduced electron‐hole pairs, accounting for the highly efficient photocatalytic performance.
      PubDate: 2015-02-25T04:21:01.919183-05:
      DOI: 10.1002/adfm.201404496
       
  • A Self‐Powered Angle Measurement Sensor Based on Triboelectric
           Nanogenerator
    • Authors: Ying Wu; Qingshen Jing, Jun Chen, Peng Bai, Junjie Bai, Guang Zhu, Yuanjie Su, Zhong Lin Wang
      Pages: n/a - n/a
      Abstract: A self‐powered, sliding electrification based quasi‐static triboelectric sensor (QS‐TES) for detecting angle from rotating motion is reported. This innovative, cost‐effective, simply‐designed QS‐TES has a two‐dimensional planar structure, which consists of a rotator coated with four channel coded Cu foil material and a stator with a fluorinated ethylenepropylene film. On the basis of coupling effect between triboelectrification and electrostatic induction, the sensor generates electric output signals in response to mechanical rotating motion of an object mounted with the sensor. The sensor can read and remember the absolute angular position, angular velocity, and acceleration regardless being continuously monitored or segmented monitored. Under the rotation speed of 100 r min−1, the output voltage of the sensor reaches as high as 60 V. Given a relatively low threshold voltage of ±0.5 V for data processing, the robustness of the device is guaranteed. The resolution of the sensor is 22.5° and can be further improved by increasing the number of channels. Triggered by the output voltage signal, the rotating characteristics of the steering wheel can be real‐time monitored and mapped by being mounted to QS‐TES. This work not only demonstrates a new principle in the field of angular measurement but also greatly expands the applicability of triboelectric nanogenerator as self‐powered sensors. A self‐powered, sliding electrification based quasi‐static triboelectric sensor for detecting angle from rotating motion is reported. The sensor reads and remembers the absolute angular position, angular velocity, and acceleration regardless being continuously monitored or segmented monitored. This work not only demonstrates a new principle in for angular measurement but also greatly expands the applicability of triboelectric nanogenerator as self‐powered sensors.
      PubDate: 2015-02-23T10:46:34.599835-05:
      DOI: 10.1002/adfm.201403828
       
  • Programmable “Semismart” Sensor: Relevance to Monitoring
           Antipsychotics
    • Authors: Eunkyoung Kim; Sheryl E. Chocron, Hadar Ben‐Yoav, Thomas E. Winkler, Yi Liu, Matthew Glassman, Christopher Wolfram, Deanna L. Kelly, Reza Ghodssi, Gregory F. Payne
      Pages: n/a - n/a
      Abstract: Mental health disorders are complex and poorly understood but would benefit from real‐time chemical analysis capable of assessing a patient's current status, personalizing a therapeutic action, and monitoring compliance. Here, an electrochemical sensor is reported for detecting the antipsychotic drug clozapine which is one of the most effective but under‐utilized drugs for managing schizophrenia. This sensor employs a composite film of multiwalled carbon nanotubes (CNTs) embedded within a matrix of the aminopolysaccharide chitosan. Chitosan allows programmable assembly of the composite film at an electrode address while the CNTs confer electrocatalytic activities that displace interfering serum peaks from the voltage region where clozapine oxidation occurs. Using differential pulse voltammetry, high sensitivities (limit of detection 0.05 × 10–6m) are demonstrated for clozapine analysis in buffer. In serum, clozapine sensitivity is reduced by an order of magnitude but still sufficient for clinical analysis. Finally, the detection of clozapine from the serum of a schizophrenia patient is demonstrated without the need for serum pretreatment. In the long term, it is envisioned that the CNT‐chitosan coated electrode could be integrated within a small array of other sensor types to enhance information‐extraction to allow mental health disorders to be better managed and better understood. A semismart electrochemical sensor is prepared from a composite film of multiwalled carbon nanotubes in a chitosan matrix. The aminopolysaccharide chitosan enables programmable assembly of the composite at an electrode address while carbon nanotubes confer electrocatalytic properties. This sensor enables highly sensitive detection of the antipsychotic medication clozapine from blood samples of schizophrenia patients without the need for sample pretreatment.
      PubDate: 2015-02-23T10:46:23.873352-05:
      DOI: 10.1002/adfm.201403783
       
  • Masthead: (Adv. Funct. Mater. 8/2015)
    • Pages: n/a - n/a
      PubDate: 2015-02-23T07:11:00.26936-05:0
      DOI: 10.1002/adfm.201570054
       
  • Thermally Stable, Biocompatible, and Flexible Organic Field‐Effect
           Transistors and Their Application in Temperature Sensing Arrays for
           Artificial Skin
    • Authors: Xiaohan Wu; Yan Ma, Guoqian Zhang, Yingli Chu, Juan Du, Yin Zhang, Zhuo Li, Yourong Duan, Zhongyong Fan, Jia Huang
      Pages: n/a - n/a
      Abstract: Application of degradable organic electronics based on biomaterials, such as polylactic‐co‐glycolic acid and polylactide (PLA), is severely limited by their low thermal stability. Here, a highly thermally stable organic transistor is demonstrated by applying a three‐arm stereocomplex PLA (tascPLA) as dielectric and substrate materials. The resulting flexible transistors are stable up to 200 °C, while devices based on traditional PLA are damaged at 100 °C. Furthermore, charge‐ trapping effect induced by polar groups of the dielectric is also utilized to significantly enhance the temperature sensitivity of the electronic devices. Skin‐like temperature sensor array is successfully demonstrated based on such transistors, which also exhibited good biocompatibility in cytotoxicity measurement. By presenting combined advantages of transparency, flexibility, thermal stability, temperature sensitivity, degradability, and biocompatibility, these organic transistors thus possess a broad applicability such as environment friendly electronics, implantable medical devices, and artificial skin. A highly thermally stable, biocompatible, and flexible organic field‐effect transistor is realized by applying a three‐arm stereocomplex polylactide as dielectric and substrate materials. Temperature sensitivity of the devices is significantly enhanced by utilizing polar‐group‐induced dielectric/semiconductor interfacial charge trapping effect. 2D temperature sensing array is demonstrated based on such transistors, which are applicable for artificial skin.
      PubDate: 2015-02-20T15:59:22.386341-05:
      DOI: 10.1002/adfm.201404535
       
  • Multifunctional Silver‐Exchanged Zeolite Micromotors for Catalytic
           Detoxification of Chemical and Biological Threats
    • Authors: Virendra V. Singh; Beatriz Jurado‐Sánchez, Sirilak Sattayasamitsathit, Jahir Orozco, Jinxing Li, Michael Galarnyk, Yuri Fedorak, Joseph Wang
      Pages: n/a - n/a
      Abstract: Multifunctional reactive‐zeolite‐based micromotors have been developed and characterized toward effective and rapid elimination of chemical and biological threats. The incorporation of silver ions (Ag+) into aluminosilicate zeolite framework imparts several attractive functions, including strong binding to chemical warfare agents (CWA) followed by effective degradation, and enhanced antibacterial activity. The new zeolite‐micromotors protocol thus combines the remarkable adsorption capacity of zeolites and the efficient catalytic properties of the reactive Ag+ ions with the autonomous movement of the zeolite micromotors for an accelerated detoxification of CWA. Furthermore, the high antibacterial activity of Ag+ along with the rapid micromotor movement enhances the contact between bacteria and reactive Ag+, leading to a powerful “on‐the‐fly” bacteria killing capacity. These attractive adsorptive/catalytic features of the self‐propelled zeolite micromotors eliminate secondary environmental contamination compared to adsorptive micromotors. The distinct cubic geometry of the zeolite micromotors leads to enhanced bubble generation and faster movement, in unique movement trajectories, which increases the fluid convection and highly efficient detoxification of CWA and killing of bacteria. The attractive capabilities of these zeolite micromotors will pave the way for their diverse applications in defense, environmental and biomedical applications in more economical and sustainable manner. Multifunctional reactive‐zeolite micromotors that combine the remarkable adsorption capacity of zeolites with the efficient catalytic properties of reactive Ag+ and the effective movement for accelerated “on‐the‐fly” detoxification of chemical and biological threats are described. The attractive capabilities of these self‐propelled zeolite micromotors will pave the way for their diverse applications in defense and environmental applications in a more economical and sustainable manner.
      PubDate: 2015-02-20T15:58:55.854895-05:
      DOI: 10.1002/adfm.201500033
       
  • Design of Hybrid MnO2‐Polymer‐Lipid Nanoparticles with Tunable
           Oxygen Generation Rates and Tumor Accumulation for Cancer Treatment
    • Authors: Claudia R. Gordijo; Azhar Z. Abbasi, Mohammad Ali Amini, Ho Yin Lip, Azusa Maeda, Ping Cai, Peter J. O'Brien, Ralph S. DaCosta, Andrew M. Rauth, Xiao Yu Wu
      Pages: n/a - n/a
      Abstract: Manganese dioxide (MnO2) nanoparticles (NPs) were discovered in previous work to be effective in improving tumor oxygenation (hypoxia) and reducing H2O2 and acidity in the tumor microenvironment (TME) via local injection. To develop MnO2 formulations useful for clinical application, hybrid NPs are designed with tailored hydrophobicity and structure suitable for intravenous injection, with good blood circulation, biocompatibility, high tumor accumulation, and programmable oxygen generation rate. Two different hybrid NPs are constructed by embedding polyelectrolyte‐MnO2 (PMD) in hydrophilic terpolymer/protein‐MnO2 (TMD) or hydrophobic polymer/lipid‐MnO2 (LMD) matrices. The in vitro reactivity of the MnO2 toward H2O2 is controlled by matrix material and NP structure and dependent on pH with up to two‐fold higher O2 generation rate at acidic (tumor) pH than at systemic pH. The hybrid NPs are found to be safe to cells in vitro and organs in vivo and effectively decrease tumor hypoxia and hypoxia‐inducible‐factor‐1alpha through local or systemic administration. Fast acting TMD reduces tumor hypoxia by 70% in 0.5 h by local injection. Slow acting LMD exhibits superior tumor accumulation and retention through the systemic administration and decreased hypoxia by 45%. These findings encourage a broader use of hybrid MD NPs to overcome TME factors for cancer treatment. Terpolymer/protein and polymer/lipid matrices are used to design hybrid MnO2 nanoparticles with tailored hydrophobicity and structure for programmable oxygen generation in the solid tumor. They feature prolonged circulation in the blood, superior tumor accumulation, and taylored reactivity with H2O2 in the acidic tumor microenvironment for the production of O­2 and modulation of tumor hypoxia through both local and systemic administration.
      PubDate: 2015-02-18T07:53:56.642383-05:
      DOI: 10.1002/adfm.201404511
       
  • Optical, Electrical, and Magnetic Studies of Organic Solar Cells Based on
           Low Bandgap Copolymer with Spin ½ Radical Additives
    • Authors: Tek Basel; Uyen Huynh, Tianyue Zheng, Tao Xu, Luping Yu, Z. Valy Vardeny
      Pages: n/a - n/a
      Abstract: The charge photogeneration and recombination processes in organic photovoltaic solar cells based on blend of the low bandgap copolymer, PTB7 (fluorinated poly‐thienothiophene‐benzodithiophene) with C60‐PCBM using optical, electrical, and magnetic measurements in thin films and devices is studied. A variety of steady state optical and magneto‐optical techniques were employed, such as photoinduced absorption (PA), magneto‐PA, doping‐induced absorption, and PA‐detected magnetic resonance (PADMR); as well as picosecond time‐resolved PA. The charge polarons and triplet exciton dynamics in films of pristine PTB7, PTB7/fullerene donor–acceptor (D–A) blend is followed. It is found that a major loss mechanism that limits the power conversion efficiency (PCE) of PTB7‐based solar cell devices is the “back reaction” that leads to triplet exciton formation in the polymer donor from the photogenerated charge‐transfer excitons at the D–A interfaces. A method of suppressing this “back reaction” by adding spin½ radicals Galvinoxyl to the D–A blend is presented; this enhances the cell PCE by ≈30%. The same method is not effective for cells based on PTB7/C70‐PCBM blend, where high PCE is reached even without Galvinoxyl radical additives. Charge transfer process in an organic photovoltaic (OPV) cell is studied in thin films and devices of a low bandgap polymer. Major loss in copolymer‐based OPV devices is the formation of triplet excitons in the polymer donor from 3CT at the donor–acceptor interfaces. A method is presented to circumvent this process by incorporating spin ½ additives.
      PubDate: 2015-02-18T07:53:42.469009-05:
      DOI: 10.1002/adfm.201403191
       
  • Triggering Mechanism for DNA Electrical Conductivity: Reversible Electron
           Transfer between DNA and Iron Oxide Nanoparticles
    • Authors: Massimiliano Magro; Davide Baratella, Petr Jakubec, Giorgio Zoppellaro, Jiri Tucek, Claudia Aparicio, Rina Venerando, Geppo Sartori, Federica Francescato, Fabio Mion, Nadia Gabellini, Radek Zboril, Fabio Vianello
      Pages: n/a - n/a
      Abstract: A new category of iron oxide nanoparticles (surface active maghemite nanoparticles (SAMNs, γ‐Fe2O3)) allows the intimate chemical and electrical contact with DNA by direct covalent binding. On these basis, different DNA‐nanoparticle architectures are developed and used as platform for studying electrical properties of DNA. The macroscopic 3D nanobioconjugate, constituted of 5% SAMNs, 70% water, and 25% DNA, shows high stability, electrochemical reversibility and, moreover, electrical conductivity (70–80 Ω cm−1). Reversible electron transfer at the interface between nanoparticles and DNA is unequivocally demonstrated by Mössbauer spectroscopy, which shows the appearance of Fe(II) atoms on nanoparticles following nanobioconjugate formation. This represents the first example of permanent electron exchange by DNA, as well as, of DNA conductivity at a macroscopic scale. Finally, the most probable configuration of the binding is tentatively modeled by density functional theory (DFT/UBP86/6‐31+G*), showing the occurrence of electron transfer from the organic orbitals of DNA to surface exposed Fe(III) on nanoparticles, as well as the generation of defects (holes) on the DNA bases. The unequivocal demonstration of DNA conduction provides a new perspective in the five decades long debate about electrical properties of this biopolymer, further suggesting novel approaches for DNA exploitation in nanoelectronics. DNA based self‐assembled nanoconjugates and a macroscopic metamaterial are synthetized, using naked maghemite nanoparticles as electroactive supports. DNA nanoconjugates show reversible electrochemical behavior and better electrochemical performances with respect to bare nanoparticles. The intimate contact between DNA and nanoparticles is studied and electron transfer at the interface between nanoparticles and DNA is unequivocally demonstrated by Mössbauer spectroscopy and modeled by density functional theory.
      PubDate: 2015-02-18T07:53:38.572356-05:
      DOI: 10.1002/adfm.201404372
       
  • Electronic Structure of Low‐Temperature Solution‐Processed
           Amorphous Metal Oxide Semiconductors for Thin‐Film Transistor
           Applications
    • Authors: Josephine Socratous; Kulbinder K. Banger, Yana Vaynzof, Aditya Sadhanala, Adam D. Brown, Alessandro Sepe, Ullrich Steiner, Henning Sirringhaus
      Pages: n/a - n/a
      Abstract: The electronic structure of low temperature, solution‐processed indium–zinc oxide thin‐film transistors is complex and remains insufficiently understood. As commonly observed, high device performance with mobility >1 cm2 V−1 s−1 is achievable after annealing in air above typically 250 °C but performance decreases rapidly when annealing temperatures ≤200 °C are used. Here, the electronic structure of low temperature, solution‐processed oxide thin films as a function of annealing temperature and environment using a combination of X‐ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and photothermal deflection spectroscopy is investigated. The drop‐off in performance at temperatures ≤200 °C to incomplete conversion of metal hydroxide species into the fully coordinated oxide is attributed. The effect of an additional vacuum annealing step, which is beneficial if performed for short times at low temperatures, but leads to catastrophic device failure if performed at too high temperatures or for too long is also investigated. Evidence is found that during vacuum annealing, the workfunction increases and a large concentration of sub‐bandgap defect states (re)appears. These results demonstrate that good devices can only be achieved in low temperature, solution‐processed oxides if a significant concentration of acceptor states below the conduction band minimum is compensated or passivated by shallow hydrogen and oxygen vacancy‐induced donor levels. The electronic structure of low‐temperature, solution‐processed Indium–Zinc–Oxide thin‐film transistors is probed, using X‐ray photoelectron spectroscopy, ultraviolet photoemission spectroscopy, and photothermal deflection spectroscopy. A compensation of a significant density of acceptor states below the conduction band by shallow hydrogen and oxygen vacancy‐induced donor levels as the key factor for achieving high device performance at low temperature is identified.
      PubDate: 2015-02-18T07:53:35.161699-05:
      DOI: 10.1002/adfm.201404375
       
  • Hybrid Z‐Scheme Using Photosystem I and BiVO4 for Hydrogen
           Production
    • Authors: Younghye Kim; Della Shin, Woo Je Chang, Hae Lin Jang, Chan Woo Lee, Hye‐Eun Lee, Ki Tae Nam
      Pages: n/a - n/a
      Abstract: The so‐called Z‐scheme is a means of utilizing photo‐induced electrons from a photosystem and has consistently motivated the design of synthetic photocatalytic systems. Although progress has been made in many pioneering studies on an inorganic‐based Z‐scheme, there have been no reports of a hybrid Z‐scheme for an inorganic and a photosystem. Here, a hybrid Z‐scheme is demonstrated by integrating a platinized photosystem I (PSI) and BiVO4 for hydrogen production. Up to now, PSI‐driven systems have been limited to a one‐step photoreduction reaction using sacrificial reductants. In this hybrid Z‐scheme, step‐wise charge separation in PSI and BiVO4 enables the production of hydrogen from only water under visible light. PSI and BiVO4 are conjugated via metal mediators to form an all‐linked structure. The novel design exhibits potential for the development of a protein hybrid system for electrochemical devices, sensors, and a solar energy conversion system. The first hybrid Z‐scheme by using photo­system I and a semiconductor in an all‐linked structure is reported. The hybrid system produces hydrogen from water without the use of a reducing additive under visible light. This novel system provides a new means of using photosynthetic proteins in photocatalytic applications.
      PubDate: 2015-02-18T07:53:27.917139-05:
      DOI: 10.1002/adfm.201404556
       
  • A–D–A‐Type Oligothiophenes for Small Molecule Organic
           Solar Cells: Extending the π‐System by Introduction of
           Ring‐Locked Double Bonds
    • Authors: Roland Fitzner; Elena Mena‐Osteritz, Karsten Walzer, Martin Pfeiffer, Peter Bäuerle
      Pages: n/a - n/a
      Abstract: A series of novel acceptor–donor–acceptor oligothiophenes terminally substituted with the 1‐(1,1‐dicyanomethylene)‐cyclohex‐2‐ene (DCC) acceptor has been synthesized. Structural, thermal, optoelectronic, and photovoltaic properties of the π‐extended DCCnTs (n = 1–4) are characterized and contrasted to the trends found for the series of parent dicyanovinyl (DCV)‐substituted oligothiophenes DCVnT. The optoelectronic properties reveal the influence of the additional exocyclic, sterically fixed double bonds in trans‐configuration in the novel DCCnT derivatives. A close correspondence for derivatives with equal number of double bonds, that is, DCCnTs and DCV(n + 1)Ts, is identified. Despite having the same energy gap, the energy levels of the frontier orbitals, HOMO and LUMO, for the DCC‐derivatives are raised and more destabilized due to the aromatization energy of a thiophene ring versus two exocyclic double bonds indicating improved donor and reduced acceptor strength. DCC‐terthiophenes give good photovoltaic performance as donor materials in vacuum‐processed solar cells (power conversion efficiencies ≤ 4.4%) clearly outperforming all comparable DCV4T derivatives. A new series of acceptor‐substituted oligothiophenes (DCCnT) is investigated. Structural, thermal, optoelectronic, and photovoltaic properties are contrasted to dicyanovinylene‐capped oligothiophenes (DCVnT). Melting temperatures and solubilities are significantly enhanced for the DCCnTs versus DCVnTs. Oligomers with equal numbers of double bonds, show very similar absorption profiles. In vacuum‐processed planar heterojunction solar cells, DCC‐terthiophenes DCC3T and DCC3T‐Me show superior photovoltaic parameters compared to conjugated corresponding DCV‐quaterthiophenes.
      PubDate: 2015-02-16T12:51:26.799493-05:
      DOI: 10.1002/adfm.201404210
       
  • Giant Phononic Anisotropy and Unusual Anharmonicity of Phosphorene:
           Interlayer Coupling and Strain Engineering
    • Authors: Yongqing Cai; Qingqing Ke, Gang Zhang, Yuan Ping Feng, Vivek B. Shenoy, Yong‐Wei Zhang
      Pages: n/a - n/a
      Abstract: Phosphorene, an emerging elemental 2D direct band gap semiconductor with fascinating structural and electronic properties distinctively different from other 2D materials such as graphene and MoS2, is promising for novel nanoelectronic and optoelectronic applications. Phonons, as one of the most important collective excitations, are at the heart of the device performance, as their interactions with electrons and photons govern the carrier mobility and light‐emitting efficiency of the material. Here, through a detailed first‐principles study, it is demonstrated that monolayer phosphorene exhibits a giant phononic anisotropy, and remarkably, this anisotropy is squarely opposite to its electronic counterpart and can be tuned effectively by strain engineering. By sampling the whole Brillouin zone for the monolayer phosphorene, several “hidden” directions are found, along which small‐momentum phonons are “frozen” with strain and possess the smallest degree of anharmonicity. Unexpectedly, these “hidden” directions are intrinsically different from the usually‐studied armchair and zigzag directions. Light is also shed on the anisotropy of interlayer coupling of few‐layer phosphorene by examining the rigid‐layer vibrations. These highly anisotropic and strain‐tunable characteristics of phosphorene offer new possibilities for its applications in thermal management, thermoelectronics, nanoelectronics, and phononics. Phosphorene, with a honeycomb lattice as graphene but puckered with ridge and accordion atomic profiles along the zigzag and armchair directions, shows a strong phonon anisotropy, and a significant orientation‐dependent interlayer coupling. Simulations reveal a more pronounced interlayer interaction and thermal leakage normal to the layer direction; accordingly, a different strategy is needed for thermal management of phosphorene devices.
      PubDate: 2015-02-16T10:21:27.348541-05:
      DOI: 10.1002/adfm.201404294
       
  • Printing Patterned Fine 3D Structures by Manipulating the Three Phase
           Contact Line
    • Authors: Lei Wu; Zhichao Dong, Minxuan Kuang, Yanan Li, Fengyu Li, Lei Jiang, Yanlin Song
      Pages: n/a - n/a
      Abstract: The preparation of fine 3D microstructures is an attractive issue; however, it is limited at large‐area fabrication process and fineness morphology manipulation. Here, we propose a strategy to fabricate controllable 3D structures and morphologies from one single droplet via ink‐jet printing. Based on the surface energy difference between the hydrophilic patterns and hydrophobic surface, the three phase contact line of a droplet contained nanoparticles is forced to pin on the patterned hydrophilic points and asymmetrically dewets on the hydrophobic surface, which leads to various morphologies. Through the regulation of pinning patterns and solution properties, the 3D morphology can be well manipulated. This strategy to control the 3D morphology of nanoparticle assembly based on hydrophilic patterns would be of great importance for fabricating controllable 3D structures. A facile strategy to directly print controllable 3D structures and morphologies from one single droplet is demonstrated. Through designing hydrophilic pattern on hydrophobic surface, the surface energy difference results in asymmetric retraction of three phase contact line, which leads to various 3D structures. This idea to precisely print the 3D structures will open a new avenue for controllable 3D manufacture.
      PubDate: 2015-02-16T10:21:25.320286-05:
      DOI: 10.1002/adfm.201404559
       
  • In Situ Preparation of Sandwich MoO3/C Hybrid Nanostructures for
           High‐Rate and Ultralong‐Life Supercapacitors
    • Authors: Hongmei Ji; Xiaolin Liu, Zhijuan Liu, Bo Yan, Lin Chen, Yafeng Xie, Chao Liu, Wenhua Hou, Gang Yang
      Pages: n/a - n/a
      Abstract: This work presents a design of sandwich MoO3/C hybrid nanostructure via calcination of the dodecylamine‐intercalated layered α‐MoO3, leading to the in situ production of the interlayered graphene layer. The sample with a high degree of graphitization of graphene layer and more interlayered void region exhibits the most outstanding energy storage performance. The obtained material is capable of delivering a high specific capacitance of 331 F g−1 at a current density of 1 A g−1 and retained 71% capacitance at 10 A g−1. In addition, nearly no discharge capacity decay between 1000 and 10 000 continuous charge–discharge cycles is observed at a high current density of 10 A g−1, indicating an excellent specific capacitance retention ability. The exceptional rate capability endows the electrode with a high energy density of 41.2 W h kg−1 and a high power density of 12.0 kW kg−1 simultaneously. The excellent performance is attributed to the sandwich hybrid nanostructure of MoO3/C with broad ion diffusion pathway, low charge‐transfer resistance, and robust structure at high current density for long‐time cycling. The present work provides an insight into the fabrication of novel electrode materials with both enhanced rate capability and cyclability for potential use in supercapacitor and other energy storage devices. A sandwich MoO3/C hybrid nanostructure assembled by α‐MoO3 and graphene layers at a molecular level provides more accessible active sites and bicontinuous pathways for quick transfer of charges inside the interlayers, as well as an excellent structure stability in the charge/discharge process. The electrode material has a high rate discharge capability accompanying with a long cycle life.
      PubDate: 2015-02-16T10:21:22.929904-05:
      DOI: 10.1002/adfm.201404378
       
  • Fluorinated Graphene in Interface Engineering of Ge‐Based
           Nanoelectronics
    • Authors: Xiaohu Zheng; Miao Zhang, Xiaohua Shi, Gang Wang, Li Zheng, Yuehui Yu, Anping Huang, Paul K. Chu, Heng Gao, Wei Ren, Zengfeng Di, Xi Wang
      Pages: n/a - n/a
      Abstract: Germanium is a promising candidate to replace silicon in nanoelectronics due to its significantly higher electron and hole mobilities. However, the unstable germanium oxide formed at the interface between the channel and dielectric layer has impeded the progress of Ge‐based nanoelectronics. By taking advantage of the impermeability of graphene, it is discovered that the insulating fluorinated graphene is able to act as an efficient diffusion barrier layer to suppress the formation of the unstable interfacial oxide in Ge‐based devices. The Ge‐based device with the fluorinated graphene exhibits negligible capacitance versus voltage hysteresis, extremely low leakage, and superior equivalent oxide thickness. First‐principles calculations reveal that interfacial diffusion, which would otherwise be unmanageable, is sufficiently obstructed by the fluorinated graphene. This new structure is expected to expedite the implementation of germanium as a channel material in next‐generation nanoelectronic devices. A barrier layer of fluorinated graphene is applied to suppress the interdiffusionand unstable interfacial oxide in HfO2/Ge‐based metal‐oxide‐semiconductor devices. The device exhibits negligible C–V hysteresis, extremely low leakage, and superior equivalent oxide thickness. The concept is expected to expedite the implementation of germanium as a channel material in next‐generation nanoelectronic devices.
      PubDate: 2015-02-14T05:48:25.438048-05:
      DOI: 10.1002/adfm.201404031
       
  • Signatures of Quantized Energy States in Solution‐Processed
           Ultrathin Layers of Metal‐Oxide Semiconductors and Their Devices
    • Authors: John G. Labram; Yen‐Hung Lin, Kui Zhao, Ruipeng Li, Stuart R. Thomas, James Semple, Maria Androulidaki, Lamprini Sygellou, Martyn McLachlan, Emmanuel Stratakis, Aram Amassian, Thomas D. Anthopoulos
      Pages: n/a - n/a
      Abstract: Physical phenomena such as energy quantization have to‐date been overlooked in solution‐processed inorganic semiconducting layers, owing to heterogeneity in layer thickness uniformity unlike some of their vacuum‐deposited counterparts. Recent reports of the growth of uniform, ultrathin (
      PubDate: 2015-02-13T06:38:01.79826-05:0
      DOI: 10.1002/adfm.201403862
       
  • N‐Type Conjugated Polymer‐Enabled Selective Dispersion of
           Semiconducting Carbon Nanotubes for Flexible CMOS‐Like Circuits
    • Authors: Huiliang Wang; Yaoxuan Li, Gonzalo Jiménez‐Osés, Peng Liu, Ya Fang, Jie Zhang, Ying‐Chih Lai, Steve Park, Liwei Chen, Kendall N. Houk, Zhenan Bao
      Pages: n/a - n/a
      Abstract: Sorting of semiconducting single‐walled carbon nanotubes (SWNTs) by conjugated polymers has attracted considerable attention recently because of its simplicity, high selectivity, and high yield. However, up to now, all the conjugated polymers used for SWNT sorting are electron‐donating (p‐type). Here, a high‐mobility electron‐accepting (n‐type) polymer poly([N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)) (P(NDI2OD‐T2)) is utilized for the sorting of high‐purity semiconducting SWNTs, as characterized by Raman spectroscopy, dielectric force spectroscopy and transistor measurements. In addition, the SWNTs sorted by P(NDI2OD‐T2) have larger diameters than poly(3‐dodecylthiophene) (P3DDT)‐sorted SWNTs. Molecular dynamics simulations in explicit toluene demonstrate distinct linear or helical wrapping geometry between P(NDI2OD‐T2) and different types of SWNTs, likely as a result of the strong interactions between the large aromatic core of the P(NDI2OD‐T2) backbone and the hexagon path of SWNTs. By using high‐mobility n‐type P(NDI2OD‐T2) as the sorting polymer, ambipolar SWNT transistors with better electron transport than that attained by P3DDT‐sorted SWNTs are achieved. As a result, flexible negated AND and negated OR logic circuits from the same set of ambipolar transistors are fabricated, without the need for doping. The use of n‐type polymers for sorting semiconducting SWNTs and achieving ambipolar SWNT transistor characteristics greatly simplifies the fabrication of flexible complementary metal‐oxide‐semiconductor‐like SWNT logic circuits. Selective dispersion of semiconducting carbon nanotubes by an n‐type conjugated polymer is demonstrated. Molecular dynamics stimulations reveal various polymer wrapping geometries for different types of nanotubes. These polymer‐wrapped semiconducting carbon nanotubes exhibit ambipolar transport, which is utilized for fabrication of flexible complementary metal‐oxide‐semiconductor‐like logic circuits without the need of n‐doping.
      PubDate: 2015-02-13T06:37:57.847653-05:
      DOI: 10.1002/adfm.201404126
       
  • Photophysics of Organic–Inorganic Hybrid Lead Iodide Perovskite
           Single Crystals
    • Authors: Hong‐Hua Fang; Raissa Raissa, Mustapha Abdu‐Aguye, Sampson Adjokatse, Graeme R. Blake, Jacky Even, Maria Antonietta Loi
      Pages: n/a - n/a
      Abstract: Hybrid organometal halide perovskites have been demonstrated to have outstanding performance as semiconductors for solar energy conversion. Further improvement of the efficiency and stability of these devices requires a deeper understanding of their intrinsic photophysical properties. Here, the structural and optical properties of high‐quality single crystals of CH3NH3PbI3 from room temperature to 5 K are investigated. X‐ray diffraction reveals an extremely sharp transition at 163 K from a twinned tetragonal I4/mcm phase to a low‐temperature phase characterized by complex twinning and possible frozen disorder. Above the transition temperature, the photoluminescence is in agreement with a band‐edge transition, explaining the outstanding performances of the solar cells. Whereas below the transition temperature, three different excitonic features arise, one of which is attributed to a free‐exciton and the other two to bound excitons (BEs). The BEs are characterized by a decay dynamics of about 5 μs and by a saturation phenomenon at high power excitation. The long lifetime and the saturation effect make us attribute these low temperature features to bound triplet excitons. This results in a description of the room temperature recombination as being due to spontaneous band‐to‐band radiative transitions, whereas a diffusion‐limited behavior is expected for the low‐temperature range. Low‐temperature photophysical investigations of CH3NH3PbI3 single crystals indicate that the recombination in these perovskites is due to spontaneous band‐to‐band radiative transition at room temperature and to singlet‐free‐exciton and bound‐triplet excitons below the phase transition temperature. The bound‐triplet excitons are characterized by a decay dynamics of about 5 μs and by a saturation phenomenon due to many‐body interactions.
      PubDate: 2015-02-13T06:37:53.374625-05:
      DOI: 10.1002/adfm.201404421
       
  • Engineering Gold Nanotubes with Controlled Length and Near‐Infrared
           Absorption for Theranostic Applications
    • Authors: Sunjie Ye; Gemma Marston, James R. McLaughlan, Daniel O. Sigle, Nicola Ingram, Steven Freear, Jeremy J. Baumberg, Richard J. Bushby, Alexander F. Markham, Kevin Critchley, Patricia Louise Coletta, Stephen D. Evans
      Pages: n/a - n/a
      Abstract: Important aspects in engineering gold nanoparticles for theranostic applications include the control of size, optical properties, cytotoxicity, biodistribution, and clearance. In this study, gold nanotubes with controlled length and tunable absorption in the near‐infrared (NIR) region have been exploited for applications as photothermal conversion agents and in vivo photoacoustic imaging contrast agents. A length‐controlled synthesis has been developed to fabricate gold nanotubes (NTs) with well‐defined shape (i.e., inner void and open ends), high crystallinity, and tunable NIR surface plasmon resonance. A coating of poly(sodium 4‐styrenesulfonate) (PSS) endows the nanotubes with colloidal stability and low cytotoxicity. The PSS‐coated Au NTs have the following characteristics: i) cellular uptake by colorectal cancer cells and macrophage cells, ii) photothermal ablation of cancer cells using single wavelength pulse laser irradiation, iii) excellent in vivo photoacoustic signal generation capability and accumulation at the tumor site, iv) hepatobiliary clearance within 72 h postintravenous injection. These results demonstrate that these PSS‐coated Au NTs have the ideal attributes to develop their potential as effective and safe in vivo imaging nanoprobes, photothermal conversion agents, and drug delivery vehicles. To the best of knowledge, this is the first in vitro and in vivo study of gold nanotubes. Gold nanotubes with controlled length and tunable absorption in the near‐infrared region are developed. The present work represents the first in vitro and in vivo study of gold nanotubes and demonstrates their effectiveness as novel agents for photoacoustic imaging and photothermal therapy with a potential of drug delivery.
      PubDate: 2015-02-12T10:42:22.972444-05:
      DOI: 10.1002/adfm.201404358
       
  • Localized Laser‐Based Photohydrothermal Synthesis of Functionalized
           Metal‐Oxides
    • Authors: Kyungmook Kwon; Jaeho Shim, Jeong Oen Lee, Kyunghan Choi, Kyoungsik Yu
      Pages: n/a - n/a
      Abstract: We discuss the rapid in situ hydrothermal synthesis of metal oxide materials based on the photothermal superheating of light‐absorbing metal layers for simple and facile on‐demand placement of semiconductor materials with micrometer‐scale lateral resolution. Localized heating from pulsed and focused laser illumination enables ultrafast growth of metal oxide materials with high spatiotemporal precision in aqueous precursor solution. Among many possible electronic and optoelectronic applications, the proposed method can be used for laser‐based in situ real‐time soldering of separated metal structures and electrodes with functionalized semiconductor materials. Resistive electrical interconnections of metal strip lines as well as sensitive UV detection using photohydrothermally grown metal oxide bumps are experimentally demonstrated. Light absorption at metal surfaces allows remote, localized generation of heat for enhanced chemical reaction rates near the beam spot. A novel class of solution‐processed metal‐oxide synthesis techniques is demonstrated that takes advantage of these effects: photohydrothermal material synthesis via pulsed laser superheating of the precursor solution. This method allows ultrafast, localized, and facile growth of functionalized metal oxide materials on metal structures.
      PubDate: 2015-02-12T10:37:25.148774-05:
      DOI: 10.1002/adfm.201404215
       
  • TPA Immobilization on Iron Oxide Nanocubes and Localized Magnetic
           Hyperthermia Accelerate Blood Clot Lysis
    • Authors: Eszter Voros; Minjung Cho, Maricela Ramirez, Anna Lisa Palange, Enrica De Rosa, Jaehong Key, Zsolt Garami, Alan B. Lumsden, Paolo Decuzzi
      Pages: n/a - n/a
      Abstract: The low specificity and high risk of intracranial hemorrhage associated with currently approved thrombolytic therapies limit their efficacy in recanalizing occluded vessels. Here, a nanoscale thrombolytic agent is demonstrated by immobilizing tissue plasminogen activator molecules (tPA) over 20 nm clustered iron oxide nanocubes (NCs). The resulting nanoconstructs (tPA–NCs) are capable of dissolving clots via both direct interaction of tPA with the fibrin network (chemical lysis) and localized hyperthermia upon stimulation of superparamagnetic NCs with alternating magnetic fields (AMFs) (mechanical lysis). In vitro, as compared to free tPA, the proposed nanoconstructs demonstrate a ≈100‐fold increase in dissolution rate, possibly because of a more intimate interaction of tPA with the fibrin network. The clot dissolution rate is further enhanced (≈10‐fold) by mild, localized heating resulting from the exposure of tPA–NCs to AMF. Intravital microscopy experiments demonstrate blood vessel reperfusion within a few minutes post tail vein injection of tPA–NCs. The proposed nanoconstructs also exhibit high transverse relaxivity (>400 × 10–3 m−1 s−1) for magnetic resonance imaging. The multifunctional properties and the 3 orders of magnitude enhancement in clot dissolution make tPA–NCs a promising nano‐theranosis agent in thrombotic disease. Clustered super‐paramagnetic 20 nm iron oxide nanocubes, stabilized by tissue plasminogen activator molecules and serum albumin, are proposed as thrombolytic agents. In vitro, as compared to tissue plasminogen activator, these nano­constructs demonstrate a ≈1000‐fold increase in dissolution rate. Intravital microscopy experiments demonstrate blood vessel reperfusion within a few minutes post tail vein injection of tissue plasminogen activator nanocubes.
      PubDate: 2015-02-11T06:52:47.753286-05:
      DOI: 10.1002/adfm.201404354
       
  • Infrared Detection Using Transparent and Flexible Field‐Effect
           Transistor Array with Solution Processable Nanocomposite Channel of
           Reduced Graphene Oxide and P(VDF‐TrFE)
    • Authors: Tran Quang Trung; Subramaniyan Ramasundaram, Nae‐Eung Lee
      Pages: n/a - n/a
      Abstract: Photodetectors using optically responsive graphene (Gr) or reduced graphene oxide (R‐GO) on rigid substrates have showed promising results for detection of broad band light including infrared (IR). However, there have been only a few reports on Gr or R‐GO photodetectors with new functionalities such as optical transparency and/or flexibility. Herein, a new kind of transparent and flexible IR photodetector is presented using a field‐effect transistor (FET) structure in which an IR‐responsive nanocomposite layer of R‐GO and poly(vinylidenefluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)) is employed as the channel. The IR photodetector exhibits high IR responsivity, stability, and reproducibility under mechanical strain and ambient conditions. In addition, the capability of measuring the distribution of responses from each device in the transparent and flexible nanocomposite FET array under IR radiation from the human body is also demonstrated. Therefore, the development of a flexible IR photodetector with high responsivity, transparency, ease of integration, and stability in an ambient environment is a suitable alternative approach for achieving the stable monitoring of IR in many flexible and transparent electronic systems. A transparent and flexible infrared photodetector array, using a field‐effect transistor structure in which an infrared‐responsive nanocomposite layer of reduced graphene oxide and P(VDF‐TrFE) is employed as a channel, exhibits high infrared responsivity, stability, and reproducibility under mechanical strain. It is possible to measure the distribution of the infrared responses from each device in a transparent and flexible nanocomposite field‐effect transistor array under infrared radiation from the human body.
      PubDate: 2015-02-11T06:51:03.555222-05:
      DOI: 10.1002/adfm.201404582
       
  • Achieving a Significantly Increased Efficiency in Nondoped Pure Blue
           Fluorescent OLED: A Quasi‐Equivalent Hybridized Excited State
    • Authors: Shitong Zhang; Liang Yao, Qiming Peng, Weijun Li, Yuyu Pan, Ran Xiao, Yu Gao, Cheng Gu, Zhiming Wang, Ping Lu, Feng Li, Shijian Su, Bing Yang, Yuguang Ma
      Pages: n/a - n/a
      Abstract: Excited state characters and components play a decisive role in photoluminescence (PL) and electroluminescence (EL) properties of organic light‐emitting materials (OLEDS). Charge‐transfer (CT) state is beneficial to enhance the singlet exciton utilizations in fluorescent OLEDs by an activated reverse intersystem crossing process, due to the minimized singlet and triplet energy splitting in CT excitons. However, the dominant CT component in the emissive state significantly reduces the PL efficiency in such materials. Here, the strategy is to carry out a fine excited state modulation, aiming to reach a golden combination of the high PL efficiency locally emissive (LE) component and the high exciton utilizing CT component in one excited state. As a result, a quasi‐equivalent hybridization of LE and CT components is obtained in the emissive state upon the addition of only an extra phenyl ring in the newly synthesized material 4‐[2‐(4′‐diphenylamino‐biphenyl‐4‐yl)‐phenanthro[9,10‐d]imidazol‐1‐yl]‐benzonitrile (TBPMCN), and the nondoped OLED of TBPMCN exhibited a record‐setting performance: a pure blue emission with a Commission Internationale de L'Eclairage coordinate of (0.16, 0.16), a high external quantum efficiency of 7.8%, and a high yield of singlet exciton of 97% without delayed fluorescence phenomenon. The excited state modulation could be a practical way to design low‐cost, high‐efficiency fluorescent OLED materials. The newly synthesized material 4‐[2‐(4′‐diphenylamino‐biphenyl‐4‐yl)‐phenanthro[9,10‐d]imidazol‐1‐yl]‐benzonitrile (TBPMCN) possesses a quasi‐equivalent hybridization of the locally emissive and charge‐transfer components in its excited state, which gives rise to its overall electroluminescence performance. The blue emissive nondoped organic light‐emitting diode of TBPMCN exhibits a very high external quantum efficiency of 7.8% with a Commission Internationale de L'Eclairage coordinate of (0.16, 0.16).
      PubDate: 2015-02-11T06:46:57.070173-05:
      DOI: 10.1002/adfm.201404260
       
  • Stoichiometry Variation in Materials with Three Mobile
           Carriers—Thermodynamics and Transport Kinetics Exemplified for
           Protons, Oxygen Vacancies, and Holes
    • Authors: D. Poetzsch; R. Merkle, J. Maier
      Pages: n/a - n/a
      Abstract: Materials with three independent mobile charge carriers, in the sense of not being in local defect‐chemical equilibrium though naturally coupled through electroneutrality, are encountered in various cases of scientific and technological relevance. Examples are proton conducting perovskites under conditions at which hole and also oxygen vacancy conductivity may become significant, and mixed conducting cathode materials suited for fuel cells using proton conducting oxide electrolytes. Already the thermodynamics of the equilibrium situation is complex as a pH2O increase can lead to proton incorporation by water uptake (pure acid–base reaction) or by hydrogenation (redox reaction). As far as the even more complex transport kinetics are concerned, diffusion equations are derived which are exact for the interaction‐free (ideally dilute) situation. Kinetic implications are discussed and checked by exemplary numerical simulations. The treatment includes simple sub‐cases such as onefold relaxation on pH2O change, as well as complex patterns characterized by the appearance of more than one characteristic time scales (“twofold relaxation”) or apparent “moving boundary” kinetics. Implications for stability and functionality of ceramic materials are discussed. Mixed conducting oxides containing oxygen vacancies, protons, and electron holes exhibit a complex kinetic behavior for water uptake: fast proton uptake at expense of holes (=reduction) followed by slow oxygen incorporation (reoxidation). Exact analytical relations are derived and this complex kinetics is illustrated by numerical simulations, which naturally explain a number of intriguing experimental observations.
      PubDate: 2015-02-10T12:23:28.938094-05:
      DOI: 10.1002/adfm.201402212
       
  • Under‐Water Superaerophobic Pine‐Shaped Pt Nanoarray Electrode
           for Ultrahigh‐Performance Hydrogen Evolution
    • Authors: Yingjie Li; Haichuan Zhang, Tianhao Xu, Zhiyi Lu, Xiaochao Wu, Pengbo Wan, Xiaoming Sun, Lei Jiang
      Pages: n/a - n/a
      Abstract: A pine‐shaped Pt nanostructured electrode with under‐water superaerophobicity for ultrahigh and steady hydrogen evolution reaction (HER) performance is successfully fabricated by a facile and easily scalable electrodeposition technique. Due to the lower bubble adhesive force (11.5 ± 1.2 μN), the higher bubble contact angle (161.3° ± 3.4°) in aqueous solution, and the smaller size of bubbles release for pine‐shaped Pt nanostructured electrode, the incomparable under‐water superaerophobicity for final repellence of bubbles from submerged surface with ease, is successfully achieved, compared to that for nanosphere electrode and for Pt flat electrode. With the merits of superior under‐water superaerophobicity and excellent nanoarray morphology, pine‐shaped Pt nanostructured electrode with the ultrahigh electrocatalytic HER performance, excellent durability, no obvious current fluctuation, and dramatically fast current density increase at overpotential range (3.85 mA mV−1, 2.55 and 13.75 times higher than that for nanosphere electrode and for Pt flat electrode, respectively), is obtained, much superior to Pt nanosphere and flat electrodes. The successful introduction of under‐water superaerophobicity to in‐time repel as‐formed H2 bubbles may open up a new pathway for designing more efficient electrocatalysts with potentially practical utilization in the near future. A Pt nanoarray electrode with under‐water superaerophobicity is fabricated by a facile and easily scalable electrodeposition technique. This electrode with a lower bubble adhesive force, a higher bubble contact angle in aqueous solution, and lower size of bubbles release, exhibits an ultrahigh electrocatalytic hydrogen evolution reaction performance, excellent durability, no obvious current fluctuation, and dramatically fast current density increase.
      PubDate: 2015-02-10T05:59:21.361655-05:
      DOI: 10.1002/adfm.201404250
       
  • Zeolite‐Coated Porous Arrays: A Novel Strategy for Enzyme
           Encapsulation
    • Authors: V. R. Reddy Marthala; Mona Friedrich, Zhou Zhou, Monica Distaso, Stephanie Reuss, Shaeel A. Al‐Thabaiti, Wolfgang Peukert, Wilhelm Schwieger, Martin Hartmann
      Pages: n/a - n/a
      Abstract: Zeolite Beta‐coated stainless steel supports with gradient porosity are employed as filter‐panels for lipase encapsulation. Enzyme encapsulation on the stainless steel porous discs is achieved via vacuum infiltration. Subsequently, two lipase‐encapsulated zeolite Beta‐coated stainless steel discs are attached using an adhesive. The zeolite Beta layer on the stainless steel discs largely prevents lipase leaching in comparison to the stainless steel discs without a zeolite layer. The activity of the lipase‐encapsulated, attached zeolite Beta‐coated stainless steel porous discs depends on the thickness of the zeolite Beta layer. It is shown that the biocatalytic performance of the lipase‐encapsulated, attached zeolite Beta‐coated stainless steel supports with a zeolite Beta layer thickness of ≈0.7–1 μm is better than the lipase‐encapsulated, attached zeolite Beta‐coated stainless steel supports with a zeolite Beta layer thickness of ≈2–3 μm in the lipase‐catalyzed transesterification of vinyl propionate with 1‐butanol using n‐hexane as solvent. Zeolite‐coated highly porous arrays with gradient porosity are used as filter‐panels for enzyme encapsulation using a novel approach. By this method the encapsulated enzyme molecules are freely mobile like in their native form within the gradient pores of stainless steel discs, while the zeolite layer on top of the discs acts as a protective layer against enzyme leaching.
      PubDate: 2015-02-10T05:58:40.618521-05:
      DOI: 10.1002/adfm.201404335
       
  • Molecular Heterojunctions of Oligo(phenylene ethynylene)s with Linear to
           Cruciform Framework
    • Authors: Zhongming Wei; Tim Hansen, Marco Santella, Xintai Wang, Christian R. Parker, Xingbin Jiang, Tao Li, Magni Glyvradal, Karsten Jennum, Emil Glibstrup, Nicolas Bovet, Xiaowei Wang, Wenping Hu, Gemma C. Solomon, Mogens Brøndsted Nielsen, Xiaohui Qiu, Thomas Bjørnholm, Kasper Nørgaard, Bo W. Laursen
      Pages: n/a - n/a
      Abstract: Electrical transport properties of molecular junctions are fundamentally affected by the energy alignment between molecular frontier orbitals (highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO)) and Fermi level (or work function) of electrode metals. Dithiafulvene (DTF) is used as substituent group to the oligo(phenylene ethynylene) (OPE) molecular wires and different molecular structures based on OPE3 backbone (with linear to cruciform framework) are achieved, with viable molecular orbitals and HOMO–LUMO energy gaps. OPE3, OPE3–DTF, and OPE3–tetrathiafulvalene (TTF) can form good self‐assembled monolayers (SAMs) on Au substrates. Molecular heterojunctions based on these SAMs are investigated using conducting probe–atomic force microscopy with different tips (Ag, Au, and Pt) and Fermi levels. The calibrated conductance values follow the sequence OPE3–TTF > OPE3–DTF > OPE3 irrespective of the tip metal. Rectification properties (or diode behavior) are observed in case of the Ag tip for which the work function is furthest from the HOMO levels of the OPE3s. Quantum chemical calculations of the transmission qualitatively agree with the experimental data and reproduce the substituent effect of DTF. Zero‐bias conductance, and symmetric or asymmetric couplings to the electrodes are investigated. The results indicate that improved fidelity of molecular transport measurements may be achieved by systematic studies of homologues series of molecular wires applying several different metal electrodes. Molecular heterojunctions based on self‐assembled monolayers of oligo(phenylene ethynylene)s, which have linear to cruciform framework, are measured by conducting probe–atomic force microscopy. Different molecular orbitals are obtained by adding the electron donating redox‐active dithiafulvene as substituent group to the OPE3 backbone. The Fermi level of the atomic force microscopy tip is tuned by different metal coating (Ag, Au, and Pt).
      PubDate: 2015-02-10T05:58:33.542117-05:
      DOI: 10.1002/adfm.201404388
       
  • Ultrafast Self‐Assembly of Graphene Oxide‐Induced Monolithic
           NiCo–Carbonate Hydroxide Nanowire Architectures with a Superior
           Volumetric Capacitance for Supercapacitors
    • Authors: Juan Yang; Chang Yu, Xiaoming Fan, Changtai Zhao, Jieshan Qiu
      Pages: n/a - n/a
      Abstract: The monolithic electrodes with high volumetric capacitance demonstrate a great potential in practical industrial applications for supercapacitors. Herein, a novel strategy for ultrafast self‐assembly of graphene oxides (GO)‐induced monolithic NiCo–carbonate hydroxide (NiCo–CH) nanowire composite films (G–CH) is reported. The oxygen‐containing functional groups on the GO surface help effectively to induce formation of the monodisperse NiCo–CH nanowires. Such a nanowire‐shaped structure further functions as a scaffold and/or support, leading to 25 s of ultrafast self‐assembly for G–CH composite films and a relatively loose and open channel that contributes to fast electrolyte transport. The as‐obtained monolithic G–CH architectures show an excellent supercapacitor performance as binder‐ and conductive agent‐free electrode, evidenced by a superior volumetric capacitance of 2936 F cm−3 and good electrochemical stability. Combining highly conductive carbon nanotubes (CNTs) into the monolithic composite films can further create well‐interconnected conductive networks within the electrode matrix, thus to improve the reaction kinetics and rate capability. The present strategy that can modulate the growth of the high‐electroactive pseudocapacitive hydroxides and achieve an ultrafast self‐assembly of monolithic composites may pave a promising new way for development of high‐performance supercapacitors and shed a new light on the configuration of carbon‐based electrode materials in energy storage and conversion devices. A novel strategy for ultrafast self‐assembly of the monolithic composite architectures (G–CH) with alternate connections of the monodisperse NiCo–carbonate hydroxide nanowires and graphene nanosheets is reported. The as‐made G–CH films exhibit a superior volumetric capacitance of 2936 F cm−3 at a current density of 1 A g−1 and excellent cycle ability.
      PubDate: 2015-02-09T06:53:29.732467-05:
      DOI: 10.1002/adfm.201404019
       
  • Alignment of Rod‐Shaped Single‐Photon Emitters Driven by Line
           Defects in Liquid Crystals
    • Authors: Laurent Pelliser; Mathieu Manceau, Clotilde Lethiec, Delphine Coursault, Stefano Vezzoli, Godefroy Leménager, Laurent Coolen, Massimo DeVittorio, Ferruccio Pisanello, Luigi Carbone, Agnes Maitre, Alberto Bramati, Emmanuelle Lacaze
      Pages: n/a - n/a
      Abstract: Arrays of liquid crystal defects—linear smectic dislocations—are used to trap semiconductor CdSe/CdS dot‐in‐rods which behave as single‐photon emitters. Measurements of the emission diagram are combined together with measurements of the emitted polarization of the single emitters. It is shown that the dot‐in‐rods are confined parallel to the linear defects to allow for a minimization of the disorder energy associated with the dislocation cores. It is demonstrated that the electric dipoles associated with the dot‐in‐rods, tilted with respect to the rods, remain oriented in the plane including the smectic linear defects and perpendicular to the substrate, most likely due to dipole/dipole interactions between the dipoles of the liquid crystal molecules and those of the dot‐in‐rods. Using smectic dislocations, nanorods can consequently be oriented along a unique direction for a given substrate, independently of the ligands' nature, without any induced aggregation, leading as well to a fixed azimuthal orientation for the dot‐in‐rods' dipoles. These results open the way for the fine control of nanoparticle anisotropic optical properties, in particular, fine control of single‐photon emission polarization. The self‐alignment of CdSe/CdS dots‐in‐rods is realized through their deposition within aligned line defects of smectic liquid crystals. The measurements of numerous single‐photon emitters evidences, for a given liquid crystal film, a unique alignment of the in‐plane dipoles associated with these particles. Fine control of the polarization of single photons emitters is thus achieved.
      PubDate: 2015-02-06T06:35:41.853844-05:
      DOI: 10.1002/adfm.201403331
       
  • Rapid Self‐Assembly of Macroscale Tissue Constructs at Biphasic
           Aqueous Interfaces
    • Authors: John P. Frampton; Brendan M. Leung, Eve L. Bingham, Sasha Cai Lesher‐Perez, Jack D. Wang, Hady T. Sarhan, Mohamed E. H. El‐Sayed, Stephen E. Feinberg, Shuichi Takayama
      Pages: n/a - n/a
      Abstract: An entirely new approach to tissue engineering is presented that uses the interfacial forces between aqueous solutions of phase‐separating polymers to confine cells and promote their assembly into interconnected, macroscopic tissue constructs. This simple and inexpensive general procedure creates free‐standing, centimeter‐scale constructs from cell suspensions at the interface between poly(ethylene glycol) and dextran aqueous two‐phase systems in as little as 2 h. Using this method, skin constructs are produced that integrate with decellularized dermal matrices, on which they differentiate and stratify into skin equivalents. It is demonstrated that the constructs produced by this method have appropriate integrity and mechanical properties for use as in vitro tissue models. Macroscopic tissue constructs composed entirely of cells are formed using the interfacial properties of aqueous two‐phase systems. The constructs form rapidly in as little as 2 h using a variety of cell types, offering a new methodology for fabricating tissue‐engineered in vitro models and cell‐based materials for regenerative therapies.
      PubDate: 2015-02-06T06:35:32.461505-05:
      DOI: 10.1002/adfm.201403825
       
  • Organic/Inorganic Hybrid Nanochannels Based on Polypyrrole‐Embedded
           Alumina Nanopore Arrays: pH‐ and Light‐Modulated Ion Transport
           
    • Authors: Qianqian Zhang; Zhaoyue Liu, Kefeng Wang, Jin Zhai
      Pages: n/a - n/a
      Abstract: Inspired by the asymmetric structure and responsive ion transport in biological ion channels, organic/inorganic hybrid artificial nanochannels exhibiting pH‐modulated ion rectification and light‐regulated ion flux have been constructed by introducing conductive polymer into porous nanochannels. The hybrid nanochannels are achieved by partially modifying alumina (Al2O3) nanopore arrays with polypyrrole (PPy) layer using electrochemical polymerization, which results in an asymmetric component distribution. The protonation and deprotonation of Al2O3 and PPy upon pH variation break the surface charge continuity, which contributes to the pH‐tunable ion rectification. The ionic current rectification ratio is affected substantially by the pH value of electrolyte and the pore size of nanochannels. Furthermore, the holes (positive charges) in PPy layer induced by the cooperative effect of light and protons are used to regulate the ionic flux through the nanochannels, which results in a light‐responsive ion current. The magnitude of responsive ionic current could be amplified by optimizing this cooperation. This new type of stimuli‐responsive PPy/Al2O3 hybrid nanochannels features advantages of unique optical and electric properties from conducting PPy and high mechanical performance from porous Al2O3 membrane, which provide a platform for creating smart nanochannels system. Organic/inorganic hybrid nanochannels are constructed by integrating conductive polypyrrole (PPy) into alumina nanopore arrays. The protonation and deprotonation of surface groups upon pH variation contribute to the pH‐tunable ion rectification. Positive charges in PPy layer induced by the cooperative effect of light and protons are used to regulate the channel flux, which results in a light‐responsive ion current.
      PubDate: 2015-02-06T06:34:47.334485-05:
      DOI: 10.1002/adfm.201404160
       
  • The Effect of Gradual Fluorination on the Properties of FnZnPc Thin Films
           and FnZnPc/C60 Bilayer Photovoltaic Cells
    • Authors: Michael Brendel; Stefan Krause, Andreas Steindamm, Anna Katharina Topczak, Sudhakar Sundarraj, Peter Erk, Steffen Höhla, Norbert Fruehauf, Norbert Koch, Jens Pflaum
      Pages: n/a - n/a
      Abstract: Motivated by the possibility of modifying energy levels of a molecule without substantially changing its band gap, the impact of gradual fluorination on the optical and structural properties of zinc phthalocyanine (FnZnPc) thin films and the electronic characteristics of FnZnPc/C60 (n = 0, 4, 8, 16) bilayer cells is investigated. UV–vis measurements reveal similar Q‐ and B‐band absorption of FnZnPc thin films with n = 0, 4, 8, whereas for F16ZnPc a different absorption pattern is detected. A correlation between structure and electronic transport is deduced. For F4ZnPc/C60 cells, the enhanced long range order supports fill factors of 55% and an increase of the short circuit current density by 18%, compared to ZnPc/C60. As a parameter being sensitive to the organic/organic interface energetics, the open circuit voltage is analyzed. An enhancement of this quantity by 27% and 50% is detected for F4ZnPc‐ and F8ZnPc‐based devices, respectively, and is attributed to an increase of the quasi‐Fermi level splitting at the donor/acceptor interface. In contrast, for F16ZnPc/C60 a decrease of the open circuit voltage is observed. Complementary photoelectron spectroscopy, external quantum efficiency, and photoluminescence measurements reveal a different working principle, which is ascribed to the particular energy level alignment at the interface of the photoactive materials. The impact of gradually fluorinated zinc phthalocyanine molecules on the photophysical properties of FnZnPc/C60 solar cells is investigated. Upon increasing fluorination, distinct variations of the cell parameters such as the open circuit voltage are observed yielding, in combination with complementary structural and electron spectroscopy analyses a detailed picture of the relevant D/A interface energetics and processes on microscopic length scales.
      PubDate: 2015-02-06T06:34:30.487783-05:
      DOI: 10.1002/adfm.201404434
       
  • Two‐Photon Nanolithography Enhances the Performance of an Ionic
           Liquid–Polymer Composite Sensor
    • Authors: Natalia A. Bakhtina; Ute Loeffelmann, Neil MacKinnon, Jan G. Korvink
      Pages: n/a - n/a
      Abstract: Continuous development of fabrication technologies, such as two‐photon polymerization (2PP), allows the exact reconstruction of specific volume shapes at micro‐ and nanometer precision. Advancements in the engineering of new materials, such as ionic liquids (ILs), are bringing superior advantages in terms of material characteristics, facilitating a combination of optical and electrical properties, as well as lithographic capabilities. In this paper, 2PP is utilized for structuring of a novel IL–polymer composite in a single‐step manufacturing process with high resolution, down to 200 nm, and high aspect ratio, up to 1:20. The composition, based on a photosensitive photoresist (e.g., IP‐L 780 or SU‐8) and the IL 1‐butyl‐3‐methylimidazolium dicyanamide, possesses a good ionic conductivity (in the range of 1–10 mS cm−1) over a wide frequency bandwidth (1 kHz–1 MHz), an electrochemical window of 2.7 V, and a good optical transparency (transmission value of 90% for a 170 μm thick film). The fabricated structures are characterized and the phenomenon of enhanced conductivity (up to 4 S cm−1) is explained. Two potential applications, including temperature and relative humidity sensing, are demonstrated as examples. The results suggest a new advanced approach for material structuring that can be regarded as highly most promising for a wide range of applications. A novel ionic liquid–polymer composite material is reported, alongside an approach for its patterning by two‐photon nanolithography. The unique properties of the material are combined with a single‐step process for its 3D structuring, having nanometer resolution and high aspect ratio. A proof‐of‐concept multifunctional sensor for temperature and relative humidity sensing is demonstrated.
      PubDate: 2015-02-05T08:17:04.519021-05:
      DOI: 10.1002/adfm.201404370
       
  • Emerging In Situ and Operando Nanoscale X‐Ray Imaging Techniques for
           Energy Storage Materials
    • Authors: Johanna Nelson Weker; Michael F. Toney
      Pages: n/a - n/a
      Abstract: Electrical vehicles (EVs) are an attractive option for moving towards a CO2 neutral transportation sector, but in order for widespread commercial use of EVs, the cost of electrical energy storage (i.e., batteries) must be reduced and the energy storage capacity must be increased. New, higher performing but Earth abundant electrodes are needed to accomplish this goal. To aid the development of these materials, in situ characterization to understand battery operation and failure is essential. Since electrodes are inherently heterogeneous, with a range of relevant length scales, imaging is a necessary component of the suite of characterization methods. In this Feature Article, the rapidly growing and developing field of X‐ray based microscopy (XM) techniques is described and reviewed focusing on in situ and operando adaptations. Further, in situ transmission electron microscopy (TEM) is briefly discussed in this context and its complement to XM is emphasized. Finally, a perspective is given on some emerging X‐ray based imaging approaches for energy storage materials. In situ X‐ray microscopy provides a powerful approach to watching battery electrode materials during realistic operation. Such experiments shed light onto operational mechanisms, including degradation and failure. This rapidly growing and developing field is described, focusing on insights gained for these inherently heterogeneous materials.
      PubDate: 2015-02-04T16:07:21.753796-05:
      DOI: 10.1002/adfm.201403409
       
  • Ambient Layer‐by‐Layer ZnO Assembly for Highly Efficient
           Polymer Bulk Heterojunction Solar Cells
    • Authors: Mohamed Eita; Abdulrahman El Labban, Federico Cruciani, Anwar Usman, Pierre M. Beaujuge, Omar F. Mohammed
      Pages: n/a - n/a
      Abstract: The use of metal oxide interlayers in polymer solar cells has great potential because metal oxides are abundant, thermally stable, and can be used in flexible devices. Here, a layer‐by‐layer (LbL) protocol is reported as a facile, room‐temperature, solution‐processed method to prepare electron transport layers from commercial ZnO nanoparticles and polyacrylic acid (PAA) with a controlled and tunable porous structure, which provides large interfacial contacts with the active layer. Applying the LbL approach to bulk heterojunction polymer solar cells with an optimized ZnO layer thickness of ≈25 nm yields solar cell power‐conversion efficiencies (PCEs) of ≈6%, exceeding the efficiency of amorphous ZnO interlayers formed by conventional sputtering methods. Interestingly, annealing the ZnO/PAA interlayers in nitrogen and air environments in the range of 60–300 °C reduces the device PCEs by almost 20% to 50%, indicating the importance of conformational changes inherent to the PAA polymer in the LbL‐deposited films to solar cell performance. This protocol suggests a new fabrication method for solution‐processed polymer solar cell devices that does not require postprocessing thermal annealing treatments and that is applicable to flexible devices printed on plastic substrates. A unique approach to fabricating bulk heterojunction polymer solar cells consisting of an electron transport layer of ZnO nanoparticles and polyacrylic acid prepared by a layer‐by‐layer technique is described. With spin‐coated active layers of poly(benzo[1,2‐b:4,5‐b′]dithiophene‐thieno[3,4‐c]pyrrole‐4,6‐dione and [6,6]‐phenyl C61 butyric acid methyl ester on a 25‐nm‐thick ZnO/polyacrylic acid layer, the power‐conversion efficiency of the solar cell is ≈6%, exceeding that of ZnO interlayers formed by sputtering.
      PubDate: 2015-02-04T16:07:02.880854-05:
      DOI: 10.1002/adfm.201402637
       
  • Synthetic Surfaces with Robust and Tunable Underwater Superoleophobicity
    • Authors: Uttam Manna; David M. Lynn
      Pages: n/a - n/a
      Abstract: Surfaces with extreme wetting properties are useful for the collection, manipulation, transport, and avoidance of aqueous and organic fluids of commercial and strategic importance. Two major obstacles to the deployment of synthetic non‐wetting materials in practical scenarios are their lack of mechanical durability and their susceptibility to fouling in contaminated or chemically complex media. Here, crosslinked and nanoporous polymer multilayers are reported that overcome these limitations and exhibit robust and tunable “underwater superoleophobicity”, or the ability to almost completely prevent contact with oils and other organic fluids when submerged in water. These entirely organic coatings mimic key chemical and structural features found on the scales of fish and other natural anti‐oil‐fouling surfaces, and are remarkably tolerant to physical, chemical, and environmental insults commonly encountered in natural and synthetic aqueous environments. This approach also permits facile manipulation and patterning of surface chemistry and, thus, tunable spatial control over other important aspects of interfacial behavior, such as underwater oil adhesiveness, that extend and expand the potential utility of synthetic anti‐oil‐fouling surfaces in aqueous, aquatic, and marine environments. Nanoporous polymer multilayers that exhibit robust and tunable underwater superoleophobicity are reported. These entirely organic coatings are tolerant to a broad range of physical, chemical, and environmental insults encountered in harsh or chemically complex media. The results provide new approaches to the design of durable anti‐oil‐fouling coatings and new principles for control over the transport, manipulation, and separation of oils and organic fluids in aqueous environments.
      PubDate: 2015-02-04T16:06:54.587313-05:
      DOI: 10.1002/adfm.201403735
       
  • Stretchable Self‐Powered Fiber‐Based Strain Sensor
    • Authors: Junwen Zhong; Qize Zhong, Qiyi Hu, Nan Wu, Wenbo Li, Bo Wang, Bin Hu, Jun Zhou
      Pages: n/a - n/a
      Abstract: The rapid development of electrical skin and wearable electronics raises the requirement of stretchable strain sensors. In this study, an active fiber‐based strain sensor (AFSS) is fabricated by coiling a fiber‐based generator around a stretchable silicone fiber. The AFSS shows the sensitive and stable performance and has the ability to detect the strain up to 25%, which is also demonstrated to detect finger motion states. It may play an essential role in future self‐powered sensor system. A fiber‐based electret generator is coiled around a stretchable silicone fiber to form an active fiber‐based strain sensor (AFSS). The AFSS shows the sensitive and stable performance and has the ability to detect the strain up to 25%, which is also demonstrated to detect finger motion states. It may play an essential role in future self‐powered sensor system.
      PubDate: 2015-02-04T16:06:05.786046-05:
      DOI: 10.1002/adfm.201404087
       
  • 3D MoS2–Graphene Microspheres Consisting of Multiple Nanospheres
           with Superior Sodium Ion Storage Properties
    • Authors: Seung Ho Choi; You Na Ko, Jung‐Kul Lee, Yun Chan Kang
      Pages: n/a - n/a
      Abstract: A novel anode material for sodium‐ion batteries consisting of 3D graphene microspheres divided into several tens of uniform nanospheres coated with few‐layered MoS2 by a one‐pot spray pyrolysis process is prepared. The first discharge/charge capacities of the composite microspheres are 797 and 573 mA h g−1 at a current density of 0.2 A g−1. The 600th discharge capacity of the composite microspheres at a current density of 1.5 A g−1 is 322 mA h g−1. The Coulombic efficiency during the 600 cycles is as high as 99.98%. The outstanding Na ion storage properties of the 3D MoS2–graphene composite microspheres may be attributed to the reduced stacking of the MoS2 layers and to the 3D structure of the porous graphene microspheres. The reduced stacking of the MoS2 layers relaxes the strain and lowers the barrier for Na+ insertion. The empty nanospheres of the graphene offer voids for volume expansion and pathways for fast electron transfer during repeated cycling. 3D MoS2–graphene composite microspheres consisting of multiple nanospheres are prepared by a one‐pot spray pyrolysis process with high scale‐up potential. The 3D MoS2–graphene composite microspheres show high reversible capacity and long cycle stability as anode materials for sodium‐ion batteries. The facile and continuous synthesis of 3D graphene‐based composite microspheres could be applied to the potential materials for various fields including energy storage.
      PubDate: 2015-02-03T11:52:54.949704-05:
      DOI: 10.1002/adfm.201402428
       
  • A Novel Design Strategy for Fully Physically Linked Double Network
           Hydrogels with Tough, Fatigue Resistant, and Self‐Healing Properties
           
    • Authors: Qiang Chen; Lin Zhu, Hong Chen, Hongli Yan, Lina Huang, Jia Yang, Jie Zheng
      Pages: n/a - n/a
      Abstract: Double network (DN) hydrogels with two strong asymmetric networks being chemically linked have demonstrated their excellent mechanical properties as the toughest hydrogels, but chemically linked DN gels often exhibit negligible fatigue resistance and poor self‐healing property due to the irreversible chain breaks in covalent‐linked networks. Here, a new design strategy is proposed and demonstrated to improve both fatigue resistance and self‐healing property of DN gels by introducing a ductile, nonsoft gel with strong hydrophobic interactions as the second network. Based on this design strategy, a new type of fully physically cross‐linked Agar/hydrophobically associated polyacrylamide (HPAAm) DN gels are synthesized by a simple one‐pot method. Agar/HPAAm DN gels exhibit excellent mechanical strength and high toughness, comparable to the reported DN gels. More importantly, because the ductile and tough second network of HPAAm can bear stress and reconstruct network structure, Agar/HPAAm DN gels also demonstrate rapid self‐recovery, remarkable fatigue resistance, and notable self‐healing property without any external stimuli at room temperature. In contrast to the former DN gels in both network structures and underlying association forces, this new design strategy to prepare highly mechanical DN gels provides a new avenue to better understand the fundamental structure‐property relationship of DN hydrogels, thus broadening current hydrogel research and applications. A new design strategy is proposed and demonstrated for a new type of double network hydrogels with both networks being fully physically linked. Agar/hydrophobically associated polyacrylamide double network gels exhibit high toughness, remarkable fatigue resistance, and notable self‐healing performance, which can be achieved by tuning the second network.
      PubDate: 2015-02-03T11:52:49.609313-05:
      DOI: 10.1002/adfm.201404357
       
  • Mobile Domain Walls as a Bridge between Nanoscale Conductivity and
           Macroscopic Electromechanical Response
    • Authors: Tadej Rojac; Hana Ursic, Andreja Bencan, Barbara Malic, Dragan Damjanovic
      Pages: n/a - n/a
      Abstract: The interfaces in complex oxides present unique properties exploitable in nanoscale devices. Recent studies on ferroelectric BiFeO3, BaTiO3, and Pb(Zr,Ti)O3 have revealed an unusually high electric conductivity of the domain walls (DWs), adding another degree of freedom for controlling the local properties of these materials. While most of the investigations are focused on thin films for nanoscale applications, many practical devices, including piezoelectric sensors, actuators, and transducers, rely on the macroscopic properties of bulk polycrystalline materials where the average effect of local properties should be small. It is shown that in polycrystalline BiFeO3 the local domain‐wall conductivity interferes with the dynamics of the DWs within the grains, resulting in an unexpectedly large effect on the macroscopic piezoelectric response. The results thus bridge the local conductivity and the macroscopic piezoelectricity via domain‐wall dynamics, revealing that the domain‐wall conductivity must be considered when interpreting and controlling macroscopic electromechanical properties. A link between electrical conductivity at the nanoscale and macroscopic electromechanical response is revealed in polycrystalline, ferroelectric BiFeO3. The existence of spontaneously formed conductive domain walls, which persist after poling, is demonstrated. It is shown that these conductive interfaces move significantly under applied subswitching electric fields, revealing emerging phenomena and large enhancement of the macroscopic piezoelectric response.
      PubDate: 2015-02-03T11:52:37.74333-05:0
      DOI: 10.1002/adfm.201402963
       
  • Novel Polygonal Vanadium Oxide Nanoscrolls as Stable Cathode for Lithium
           Storage
    • Authors: Qiulong Wei; Shuangshuang Tan, Xiaoyi Liu, Mengyu Yan, Fengchao Wang, Qidong Li, Qinyou An, Ruimin Sun, Kangning Zhao, Hengan Wu, Liqiang Mai
      Pages: n/a - n/a
      Abstract: Scroll‐shape structures with adjustable space provide interlayer sliding to accommodate the volume changes, which are promising candidates for increasing the stability of lithium batteries (LBs). In this work, for the first time, novel vanadium oxide polygonal nanoscrolls (PNSs) are synthesized in solution through self‐rolling, Ostwald ripening, and scroll‐by‐scroll processes. The PNSs are of various shapes (including triangle, quadrangle, pentagon, and so forth) and spiral‐wrapped multiwall. When evaluated as cathode for LB, the vanadium oxide PNSs cathode exhibits largely enhanced cycling stability (capacity retention of 91.7% after 150 cycles at 0.1 A g–1 in 2.0–4.0 V) compared with those of nonscrolled nanobelts (40.0%) and nanowires (35.8%). Even at 1.0 A g–1, the PNSs cathode delivers high‐rate long‐life performance with capacity retention of 80.6% after 500 cycles. The unique polygonal nanoscroll structure is favorable for improving the cyclability and rate capability in energy storage applications as demonstrated here, and it will be interesting and has great potential for other related applications. Polygonal inorganic nanoscrolls are successfully synthesized for the first time via a self‐rolling, Ostwald ripening, and scroll‐by‐scroll process in aqueous solution. This kind of novel polygonal nanoscroll structure represents an interesting model with robust outwall and expandable inner space which buffers the swelling stress during cycling, resulting in the largely enhanced cycling stability. This novel structure is interesting and has great potential in other applications.
      PubDate: 2015-02-03T11:52:31.606112-05:
      DOI: 10.1002/adfm.201404311
       
  • A Facile In Situ Approach to Polypyrrole Functionalization Through
           Bioinspired Catechols
    • Authors: Wei Zhang; Zihe Pan, Fut K. Yang, Boxin Zhao
      Pages: n/a - n/a
      Abstract: A template‐free benign approach to modify polypyrrole (PPy) with bioinspired catechol derivatives dopamine (DA), 1,2‐dihydroxybenzene or catechol (CA), and l‐3,4‐dihydroxyphenylalanine (DOPA) is reported. It is found that PPy functionalized with these catechol derivatives (DA, CA, and DOPA) exhibited fibrous structure, smaller particle size, good water dispersibility, and enhanced film adhesion. Surprisingly, it is found that adding a small amount of catechols can also improve PPy's electrical conductivity. This rapid, one‐step, in situ, template‐free method provided an alternative strategy to the facile production of PPy fibers. Among these three catechols, functionalized PPy and DA‐PPy exhibits the smallest particle size and best performance in both adhesion and electrical conductivity. In contrast, the control phenylethlamine (PA) modification had almost negligible influence on the PPy properties, which provides strong evidence that instead of amine functional group or coexistence of both catechol and amine moieties, catechol itself is responsible for the successful functionalization of PPy and overall performance improvement. Furthermore, catechol‐PPy nanofibers are blended into polyvinyl alcohol (PVA) aqueous solution and casted to form thin films; as‐synthesized conductive films are found able to bond strongly onto the surface and may find broad applications in manufacturing biosensors and electronic devices. A benign one‐step approach to synthesize novel catechol‐polypyrrole (PPy) nanocomposties with a fibrous structure, good water dispersibility, enhanced film adhesion, and improved electrical conductivity is reported. Such functionalized PPy nanofibers can be uniformly dispersed into polyvinyl alcohol polymer matrix and casted into thin‐film coating; as‐prepared coating exhibited high scratch resistance, biocompatibility, and conductivity, would find broad industrial applications.
      PubDate: 2015-01-29T12:26:29.824794-05:
      DOI: 10.1002/adfm.201403115
       
  • Cohesively Enhanced Conductivity and Adhesion of Flexible Silver Nanowire
           Networks by Biocompatible Polymer Sol‐Gel Transition
    • Authors: Yunxia Jin; Lu Li, Yuanrong Cheng, Lingqiang Kong, Qibing Pei, Fei Xiao
      Pages: n/a - n/a
      Abstract: Silver nanowire (AgNW) networks are a promising candidate to replace indium tin oxide (ITO) as transparent conductors. In this paper, a novel transparent composite conductor composed of AgNW/biocompatible alginate gel on a flexible polyethylene terephthalate (PET) substrate, with synchronously enhanced adhesion and reduced resistivity, is prepared without high‐temperature annealing. The sheet resistance of the flexible AgNW/PET film reduces from 300 to 50.3 Ohm sq−1 at transmittance of 94%. The optical and electrical performance is superior to that obtained from the flexible ITO film on PET. Meanwhile, the sheet resistance does not show great change after tape test, suggesting a good adhesion of AgNW to the polymer substrate. Moreover, the AgNW composite film shows a good stability to resist long‐term storage, solvent damage, and ultrasonication. Finally, polymer solar cells employing the composite AgNW film as the electrode are realized, displaying an efficiency of 2.44%. Flexible Ag nanowire (NW)/Ca alginate composite transparent electrodes with cohesively improved adhesion and conductivity are prepared without high‐temperature annealing. The bivalent calcium ions cross‐link the alginate under the AgNW networks to form water‐resist alginate gel to bond the AgNWs tightly on the substrate; the chloride ions detach the stabilizer on the surface of the Ag nano­wire to trigger the sintering.
      PubDate: 2015-01-29T12:26:19.088855-05:
      DOI: 10.1002/adfm.201403293
       
  • Polypyrrole Asymmetric Bilayer Artificial Muscle: Driven Reactions,
           Cooperative Actuation, and Osmotic Effects
    • Authors: Masaki Fuchiwaki; Jose G. Martinez, Toribio F. Otero
      Pages: n/a - n/a
      Abstract: The coulo‐dynamic (angle/consumed charge) characterization of an asymmetric polypyrrole (PPy) bending bilayer (PPy1/PPy2) muscle is performed in aqueous solutions by cyclic voltammetry with parallel video recording of a reversible angular displacement of 200°. The characterization of each of the two PPy1/tape, PPy2/tape muscles, describing 30° and 50° per voltammetric cycle, corroborates the driven muscle reactions and ionic exchanges. The asymmetric bilayer efficiency, as described degrees per reaction unit, is seven and four times that of the PPy/tape muscles. A cooperative electro‐chemo‐mechanical actuation of each of the individual layers occurs in the asymmetric bilayer. Each of the three muscles is a Faradaic polymeric motor: described angles are linear functions of the consumed charge with small hysteresis loops. Each loop is related to dynamic water osmotic balance following the reaction driven film swelling or its fast electro‐osmotic expulsion around the reduction induced conformational closing and film compaction. Polypyrrole asymmetric bilayer (PPy1/PPy2) bending muscles with asymmetric volume changes under reaction driven ionic exchanges originate cooperative electro‐chemo‐mechanical effects. Osmotic and electro‐osmotic processes, following ionic entrance or preceding conformational compaction processes, complement the muscle actuation.
      PubDate: 2015-01-29T12:25:35.694606-05:
      DOI: 10.1002/adfm.201404061
       
  • Dual Support System Ensuring Porous Co–Al Hydroxide Nanosheets with
           Ultrahigh Rate Performance and High Energy Density for Supercapacitors
    • Authors: Xiaoliang Wu; Lili Jiang, Conglai Long, Tong Wei, Zhuangjun Fan
      Pages: n/a - n/a
      Abstract: Layered double hydroxides (LDHs) are promising supercapacitor electrode materials due to their high specific capacitances. However, their electrochemical performances such as rate performance and energy density at a high current density, are rather poor. Accordingly, a facile strategy is demonstrated for the synthesis of the integrated porous Co–Al hydroxide nanosheets (named as GSP‐LDH) with dual support system using dodecyl sulfate anions and graphene sheets as structural and conductive supports, respectively. Owing to fast ion/electron transport, porous and integrated structure, the GSP‐LDH electrode exhibits remarkably improved electrochemical characteristics such as high specific capacitance (1043 F g−1 at 1 A g−1) and ultra‐high rate performance capability (912 F g−1 at 20 A g−1). Moreover, the assembled sandwiched graphene/porous carbon (SGC)//GSP‐LDH asymmetric supercapacitor delivers a high energy density up to 20.4 Wh kg−1 at a very high power density of 9.3 kW kg−1, higher than those of previously reported asymmetric supercapacitors. The strategy provides a facile and effective method to achieve high rate performance LDH based electrode materials for supercapacitors. Integrated porous Co–Al hydroxide nanosheets with dual support system (GSP‐LDH) are synthesized by using dodecyl sulfate anions as structural support and graphene sheets as conductive support. The as‐obtained GSP‐LDH electrode exhibits high specific capacitance and ultra‐high rate capability. Moreover, the assembled porous carbon//GSP‐LDH asymmetric supercapacitor exhibits a high energy density up at a very high power density.
      PubDate: 2015-01-29T12:25:29.17373-05:0
      DOI: 10.1002/adfm.201404142
       
  • Tumor Microenvironment Activated Photothermal Strategy for Precisely
           Controlled Ablation of Solid Tumors upon NIR Irradiation
    • Authors: Enguo Ju; Kai Dong, Zhen Liu, Fang Pu, Jinsong Ren, Xiaogang Qu
      Pages: n/a - n/a
      Abstract: Photothermal ablation has provided emerging and promising opportunities to further potentiate the efficacy of postoperative chemotherapy of tumor. However, it still cannot achieve a high level of selectivity because extraneous photodamage along the optical path to the tumor is unavoidable as the result of the uncontrollable distribution of the photothermal agents. In addition, it is technically difficult to keep photoirradiation localizing only on cancer cells. In this report, a new strategy is introduced for precisely controlled ablation of tumor through tumor microenvironment activated near‐infrared (NIR) photothermal therapy. By taking advantage of the pH‐dependent light‐heat conversion property of Au@PANI nanoparticles, much higher photothermal effect at pH 6.5 than that at pH 7.4 is achieved. Therefore, in normal tissues and blood vessels, NIR irradiation cannot lead to a lethal temperature with little or no harm to normal cells. In contrast, in acidic tumor microenvironment, the photothermal effect is activated. Consequently, NIR irradiation can effectively kill cancer cells through local hyperthermia. Importantly, with the benefit of the internal and external control to switch on the photothermal ablation, the technical difficulty to precisely localize laser irradiation on tumor cells can be circumvented. A tumor microenvironment activated photothermal strategy is presented based on pH‐dependent light‐heat conversion property of Au@PANI nanoparticles. The tumor acidic microenvironment‐activated photothermal effect exhibits highly discriminating photo‐induced damage to tumor region while leaving normal tissues intact. With the benefit of the control to switch on the photothermal ablation, technical difficulty to precisely operate laser irradiation on tumor cells can be circumvented.
      PubDate: 2015-01-28T11:13:54.869244-05:
      DOI: 10.1002/adfm.201403885
       
  • Reduced Graphene Oxide Micromesh Electrodes for Large Area, Flexible,
           Organic Photovoltaic Devices
    • Authors: Dimitrios Konios; Constantinos Petridis, George Kakavelakis, Maria Sygletou, Kyriaki Savva, Emmanuel Stratakis, Emmanuel Kymakis
      Pages: n/a - n/a
      Abstract: A laser‐based patterning technique—compatible with flexible, temperature‐sensitive substrates—for the production of large area reduced graphene oxide micromesh (rGOMM) electrodes is presented. The mesh patterning can be accurately controlled in order to significantly enhance the electrode transparency, with a subsequent slight increase in the sheet resistance, and therefore improve the tradeoff between transparency and conductivity of reduced graphene oxide (rGO) layers. In particular, rGO films with an initial transparency of ≈20% are patterned, resulting in rGOMMs films with a ≈59% transmittance and a sheet resistance of ≈565 Ω sq−1, that is significantly lower than the resistance of ≈780 Ω sq−1, exhibited by the pristine rGO films at the same transparency. As a proof‐of‐concept application, rGOMMs are used as the transparent electrodes in flexible organic photovoltaic (OPV) devices, achieving power conversion efficiency of 3.05%, the highest ever reported for flexible OPV devices incorporating solution‐processed graphene‐based electrodes. The controllable and highly reproducible laser‐induced patterning of rGO hold enormous promise for both rigid and flexible large‐scale organic electronic devices, eliminating the lag between graphene‐based and indium–tin oxide electrodes, while providing conductivity and transparency tunability for next generation flexible electronics. A direct laser writing technique is demonstrated for the fabrication of reduced graphene oxide micromesh electrodes with high conductivity and transparency. Their utilization as the transparent electrode in flexible organic photovoltaic (OPV) devices leads to a power conversion efficiency of 3.05%, which is the highest ever reported for flexible OPVs based on solution‐processed graphene electrodes.
      PubDate: 2015-01-28T11:13:51.106512-05:
      DOI: 10.1002/adfm.201404046
       
  • PEGylated Polypyrrole Nanoparticles Conjugating Gadolinium Chelates for
           Dual‐Modal MRI/Photoacoustic Imaging Guided Photothermal Therapy of
           Cancer
    • Authors: Xiaolong Liang; Yanyan Li, Xiaoda Li, Lijia Jing, Zijian Deng, Xiuli Yue, Changhui Li, Zhifei Dai
      Pages: n/a - n/a
      Abstract: Polypyrrole nanoparticles conjugating gadolinium chelates were successfully fabricated for dual‐modal magnetic resonance imaging (MRI) and photoacoustic imaging guided photothermal therapy of cancer, from a mixture of pyrrole and pyrrole‐1‐propanoic acid through a facile one‐step aqueous dispersion polymerization, followed by covalent attachment of gadolinium chelate, using polyethylene glycol as a linker. The obtained PEGylated poly­pyrrole nanoparticles conjugating gadolinium chelates (Gd‐PEG‐PPy NPs), sized around around 70 nm, exhibited a high T1 relaxivity coefficient of 10.61 L mm−1 s−1, more than twice as high as that of the relating free Gd3+ complex (4.2 L mm–1 s−1). After 24 h intravenous injection of Gd‐PEG‐PPy NPs, the tumor sites exhibited obvious enhancement in both T1‐weighted MRI intensity and photoacoustic signal compared with that before injection, indicating the efficient accumulation of Gd‐PEG‐PPy NPs due to the introduction of the PEG layer onto the particle surface. In addition, tumor growth could be effectively inhibited after treatment with Gd‐PEG‐PPy NPs in combination with near‐infrared laser irradiation. The passive targeting and high MRI/photo­acoustic contrast capability of Gd‐PEG‐PPy NPs are quite favorable for precise cancer diagnosing and locating the tumor site to guide the external laser irradiation for photothermal ablation of tumors without damaging the surrounding healthy tissues. Therefore, Gd‐PEG‐PPy NPs may assist in better monitoring the therapeutic process, and contribute to developing more effective “personalized medicine,” showing great potential for cancer diagnosis and therapy. A theranostic agent with excellent physiological stability, strong NIR absorption, and high magnetization is fabricated from PEGylated polypyrrole nanoparticles conjugating gadolinium chelates (Gd‐PEG‐PPy NPs). The passive targeting and high MRI/photoacoustic contrast capability of Gd‐PEG‐PPy NPs are favorable for precise cancer diagnosing, and locating tumor sites to guide external laser irradiation for photothermal ablation of tumors without damaging surrounding healthy tissue.
      PubDate: 2015-01-28T04:51:17.163038-05:
      DOI: 10.1002/adfm.201402338
       
  • Novel Molybdenum Carbide–Tungsten Carbide Composite Nanowires and
           Their Electrochemical Activation for Efficient and Stable Hydrogen
           Evolution
    • Authors: Peng Xiao; Xiaoming Ge, Haibo Wang, Zhaolin Liu, Adrian Fisher, Xin Wang
      Pages: n/a - n/a
      Abstract: Development of nonnoble metal catalysts for hydrogen evolution reaction (HER) is critical to enable an efficient production of hydrogen at low cost and large scale. In this work, a novel bimetallic carbide nanostructure consisting of Mo2C and WC is synthesized. Based on a highly conductive WC backbone, nanosized Mo2C particles are integrated onto WC, forming a well‐defined and highly robust nanowire structure. More importantly, it is found that electrochemical activation can partially remove surface carbon and activate the catalyst by changing its surface hydrophilicity. As a result, the residual carbon contributes positively to the activity, besides its role of protecting carbide from oxidation. Benefiting from the structure, the catalyst achieves high activity, stable electrolysis towards HER. The well‐defined nanowire structure of complex molybdenum carbide–tungsten carbide is realized by a pseudomorphic transformation and exhibits high activity towards hydrogen evolution reaction after electrochemical activation.
      PubDate: 2015-01-27T08:30:16.282086-05:
      DOI: 10.1002/adfm.201403633
       
  • Lanthanide Ion Codoped Emitters for Tailoring Emission Trajectory and
           Temperature Sensing
    • Authors: Shu‐Na Zhao; Lei‐Jiao Li, Xue‐Zhi Song, Min Zhu, Zhao‐Min Hao, Xing Meng, Lan‐Lan Wu, Jing Feng, Shu‐Yan Song, Cheng Wang, Hong‐Jie Zhang
      Pages: n/a - n/a
      Abstract: A series of lanthanide metal‐organic frameworks (Ln‐MOFs) are synthesized through solvothermal conditions with 1,3‐bis(4‐carboxyphenyl)imidazolium (H2L). Owing to the lanthanide contraction effect, two different types of Ln‐MOFs, namely, {[Ln(L)2(OH)]·3H2O}n (Ln:Pr, Nd, Sm) and {[Ln(L)2(COO)(H2O)2]·H2O}n (Ln: Eu, Gd, Tb, Dy, Tm, Yb, Y), and their corresponding codoped Ln‐MOFs EuxTb1‐xL are obtained. With careful adjustment of the relative concentration of the lanthanide ions and the excitation wavelength, the color of the luminescence can be systematically modulated and white light emission can be further successfully achieved. Furthermore, by virtue of the temperature‐dependent luminescent behavior, Eu0.2Tb0.8L allows for the design of a thermometer with an excellent linear response to temperature over a wide range, from 40 to 300 K. This work highlights the practical applications of Ln‐MOFs for tailoring fluorescent color and even obtaining practical white light emission, and especially for sensing temperature as luminescent thermometers in a single framework by controlling in different ways. Codoped Ln‐metal‐organic frameworks EuxTb1‐xL are synthesized based on the isostructural Ln‐metal‐organic frameworks using lanthanide ion emitters. With careful adjustment of the relative concentration of the lanthanide ions and the excitation wavelength, the emission trajectory can be modulated, allowing white emission. Furthermore, Eu0.2Tb0.8L allows for the design of a thermometer operating over a wide range, from 40 to 300 K.
      PubDate: 2015-01-27T08:28:47.97862-05:0
      DOI: 10.1002/adfm.201402061
       
  • Nanorods: Discotic Liquid Crystal‐Functionalized Gold Nanorods:
           2‐ and 3D Self‐Assembly and Macroscopic Alignment as well as
           Increased Charge Carrier Mobility in Hexagonal Columnar Liquid Crystal
           Hosts Affected by Molecular Packing and π–π Interactions
           (Adv. Funct. Mater. 8/2015)
    • Authors: Xiang Feng; Lydia Sosa‐Vargas, S. Umadevi, Taizo Mori, Yo Shimizu, Torsten Hegmann
      Pages: 1161 - 1161
      Abstract: On page 1180, T. Hegmann and team show that gold nanorods decorated with discotic liquid crystals self‐assemble into nanorod ribbons both in thin films on TEM grids as well as in the bulk. These nanorods can be aligned with over 75% efficiency based on the calculated order parameter and enhance the charge carrier mobility in the parent discotic liquid crystal host. The image shows the texture of the hexagonal columnar liquid crystal host H6TP doped with the functionalized gold nanorods at 1% by weight.
      PubDate: 2015-02-23T07:10:59.711852-05:
      DOI: 10.1002/adfm.201570051
       
  • Organic Heterojunctions: Electronic Structures and Photoconversion
           Mechanism in Perovskite/Fullerene Heterojunctions (Adv. Funct. Mater.
           8/2015)
    • Authors: Ming‐Fai Lo; Zhi‐Qiang Guan, Tsz‐Wai Ng, Chiu‐Yee Chan, Chun‐Sing Lee
      Pages: 1162 - 1162
      Abstract: Photocharge generation mechanisms in perovskite solar cells are examined by T.‐W. Ng, C.‐S. Lee, and co‐workers on page 1213. It is found that perovskites/C60 is in fact an inert N–N junction providing no driving force for charge separation. Photovoltaic effects in perovskite solar cells are attributed to direct free‐carrier generation within the perovskite film.
      PubDate: 2015-02-23T07:10:56.22846-05:0
      DOI: 10.1002/adfm.201570052
       
  • Contents: (Adv. Funct. Mater. 8/2015)
    • Pages: 1163 - 1169
      PubDate: 2015-02-23T07:10:52.972013-05:
      DOI: 10.1002/adfm.201570053
       
  • Edge‐Fluorinated Graphene Nanoplatelets as High Performance
           
    • Authors: In‐Yup Jeon; Myung Jong Ju, Jiantie Xu, Hyun‐Jung Choi, Jeong‐Min Seo, Min‐Jung Kim, In Taek Choi, Hong Mo Kim, Jae Cheon Kim, Jae‐Joon Lee, Hua Kun Liu, Hwan Kyu Kim, Shixue Dou, Liming Dai, Jong‐Beom Baek
      Pages: 1170 - 1179
      Abstract: Edge‐selectively fluorinated graphene nanoplatelets (FGnPs) are prepared by mechanochemically driven reaction between fluorine gas (20 vol% in argon) and activated carbon species from graphitic C–C bonds unzipped by high‐speed stainless steel balls with a high kinetic energy. The fluorination at edges of the unzipped graphene nanoplatelets (GnPs) is confirmed by various analytical techniques while the content of fluorine in FGnPs is determined to be 3.0 and 3.4 at% by X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray spectroscopy, respectively. Because of the large difference in electronegativity between carbon (χ = 2.55) and fluorine (χ = 3.98) and the strong C–F bond, the edge‐fluorination of GnPs can provide the maximized charge polarization with an enhanced chemical stability. Thus, electrodes based on the resultant FGnPs demonstrate superb electrochemical performance with excellent stability/cycle life in dye‐sensitized solar cells (FF: 71.5%; Jsc: 14.44 mA cm−2; Voc: 970 mV; PCE: 10.01%) and lithium ion batteries (650.3 mA h g−1 at 0.5 C, charge retention of 76.6% after 500 cycles). Edge‐selectively fluorinated graphene nanoplatelets (FGnPs) are prepared by simple mechanochemical ball‐milling graphite in the presence of fluorine/argon (20/80, v/v). The FGnPs demonstrate superb electrochemical performance with excellent stability/cycle life in dye‐sensitized solar cells and lithium ion batteries.
      PubDate: 2015-01-08T08:06:19.666579-05:
      DOI: 10.1002/adfm.201403836
       
  • Liquid Crystals: Liquid‐Crystalline Electrolytes for
           Lithium‐Ion Batteries: Ordered Assemblies of a
           Mesogen‐Containing Carbonate and a Lithium Salt (Adv. Funct. Mater.
           8/2015)
    • Authors: Junji Sakuda; Eiji Hosono, Masafumi Yoshio, Takahiro Ichikawa, Takuro Matsumoto, Hiroyuki Ohno, Haoshen Zhou, Takashi Kato
      Pages: 1205 - 1205
      Abstract: The application of thermotropic liquid‐crystalline (LC) electrolytes to lithium‐ion batteries is demonstrated for the first time by T. Kato and co‐workers on page 1206. The LC electrolytes form 2D ion‐conductive pathways in their LC layered nanostructures. The electrolytes are the mixtures of a carbonate‐based rod‐like molecule and lithium bis(trifluoromethylsulfonyl)imide. The electrolytes show stable charge–discharge behavior for electrodes of lithium‐ion batteries.
      PubDate: 2015-02-23T07:10:55.005757-05:
      DOI: 10.1002/adfm.201570055
       
  • Conductive “Smart” Hybrid Hydrogels with PNIPAM and
           Nanostructured Conductive Polymers
    • Authors: Ye Shi; Chongbo Ma, Lele Peng, Guihua Yu
      Pages: 1219 - 1225
      Abstract: Stimuli‐responsive hydrogels with decent electrical properties are a promising class of polymeric materials for a range of technological applications, such as electrical, electrochemical, and biomedical devices. In this paper, thermally responsive and conductive hybrid hydrogels are synthesized by in situ formation of continuous network of conductive polymer hydrogels crosslinked by phytic acid in poly(N‐isopropylacrylamide) matrix. The interpenetrating binary network structure provides the hybrid hydrogels with continuous transporting path for electrons, highly porous microstructure, strong interactions between two hydrogel networks, thus endowing the hybrid hydrogels with a unique combination of high electrical conductivity (up to 0.8 S m−1), high thermoresponsive sensitivity (significant volume change within several seconds), and greatly enhanced mechanical properties. This work demonstrates that the architecture of the filling phase in the hydrogel matrix and design of hybrid hydrogel structure play an important role in determining the performance of the resulting hybrid material. The attractive performance of these hybrid hydrogels is further demonstrated by the developed switcher device which suggests potential applications in stimuli‐responsive electronic devices. Thermal‐responsive and conductive hybrid hydrogels are synthesized by the in situ formation of a continuous network of conductive polymer hydrogels in a poly(N‐isopropylacrylamide) matrix. The interpenetrating binary network structure provides the hybrid hydrogels with a continuous electron transport path, highly porous microstructure, and strong interactions between networks, thus endowing them with a unique combination of high electrical conductivity, high thermal‐responsive sensitivity, and good mechanical properties.
      PubDate: 2015-01-14T07:11:16.500508-05:
      DOI: 10.1002/adfm.201404247
       
  • Tunable Near UV Microcavity OLED Arrays: Characterization and Analytical
           Applications
    • Authors: Eeshita Manna; Fadzai Fungura, Rana Biswas, Joseph Shinar, Ruth Shinar
      Pages: 1226 - 1232
      Abstract: A new approach is demonstrated to fabricate narrow‐band emission near‐UV microcavity OLEDs (μcOLEDs) with peak emission at ≈385 nm, in near‐perfect alignment with the narrow primary 385 nm absorption band of Pt octaethylporphyrin dye, using 4,4′‐bis(9‐carbazolyl)‐1,1′‐biphenyl (CBP) as the emissive layer. Although OLEDs have been extensively operated at optical wavelengths, only few have achieved near‐UV emission. Yet there is a growing need for portable compact narrow‐band near UV sources for many biomedical and forensic applications. A microcavity effect, due to metallic electrodes enclosing an optical cavity, is employed to achieve the desired narrow peak emission. An Al/Pd bi‐layer anode enables attaining a turn on voltage of 3.8 V and a 4,4′‐cyclohexylidenebis [N,N‐bis (4‐methylphenyl) benzenamine] (TAPC) layer improves electron‐hole recombination in the emissive layer. The fabricated μcOLED is efficiently used as the excitation source in a structurally integrated all‐organic oxygen sensor. Moreover, a CBP‐based combinatorial array of μcOLED pixels is fabricated by varying the thickness of the organic layers to obtain nine sharp, discrete emission peaks from 370 to 430 nm, employed in an all‐organic on‐chip spectrophotometer. The photodetectors are based on P3HT:PCBM (poly(3‐hexylthiophene):[6,6]‐phenyl‐C60‐butyric acid methyl ester) or the more sensitive PTB7:PCBM (PTB7 is polythieno [3,4‐b]‐thiophene‐co‐benzodithiophene). Simulations of the OLEDs' emission are used for analysis of the experimental data, assisting in device fabrication. Near‐UV microcavity CBP‐based OLEDs (peak emission ≈385 nm) with Al/Pd anode exhibit increased irradiance and lower turn‐on voltage in comparison to other CBP‐based OLEDs. The peak emission is well aligned with the narrow 385 nm absorption band of the ubiquitous PtOEP. A tunable microcavity OLED array (peak electroluminescence 370–430 nm) is utilized in an all‐organic (OLED/sensing film/OPD) on‐chip spectrophotometer.
      PubDate: 2015-01-16T02:41:38.218242-05:
      DOI: 10.1002/adfm.201403313
       
  • Unraveling the Gain Mechanism in High Performance Solution‐Processed
           PbS Infrared PIN Photodiodes
    • Authors: Jae Woong Lee; Do Young Kim, Franky So
      Pages: 1233 - 1238
      Abstract: High gain and low dark current solution‐processed colloidal PbS quantum dots infrared (IR) PIN photodetectors with IR sensitivity up to 1500 nm are demonstrated. The low dark current is due to the P‐I‐N structure with both electron and hole blockers. The high gain in our IR photodiodes is due to the enhancement of electron tunneling injection through the 1,1‐bis[(di‐4‐tolylamino) phenyl]cyclohexane (TAPC) electron blocker under IR illumination resulting from a distorted electron blocking barrier in the presence of photo‐generated holes trapped in the TAPC electron blocker. It is further found that the trap states in the TAPC layer are generated by the Ag atoms penetrated in the TAPC layer during the thermal evaporation process. The resulting photodetectors have a high detectivity value of 7 × 1013 Jones, which is even higher than that of a commercial InGaAs photodiode. High gain solution processed PbS nanocrystals photodetectors with a gain of 187 are demonstrated with an infrared sensitivity up to 1500 nm. The photodetectors have a high detectivity of 7 × 1013 Jones, which is even higher than that of a commercial InGaAs photodiode. The gain is due to the enhancement of electron injection through the TAPC electron blocking layer.
      PubDate: 2015-01-21T05:04:08.720028-05:
      DOI: 10.1002/adfm.201403673
       
  • Fluorescent Materials: Highly Fluorescent Thienoviologen‐Based
           Polymer Gels for Single Layer Electrofluorochromic Devices (Adv. Funct.
           Mater. 8/2015)
    • Authors: Amerigo Beneduci; Sante Cospito, Massimo La Deda, Giuseppe Chidichimo
      Pages: 1239 - 1239
      Abstract: The tuning of both color and intensity of photoluminescence is of the utmost importance for several applications in displays, sensors, optical data storage, in vivo imaging, or molecular logic gates. On page 1240, A. Beneduci and co‐workers incorporate a highly fluorescent liquid crystal thienoviologen in a polymer gel, and efficiently achieve reversible electrofluorescence intensity switching, in the visible spectral range between green and red.
      PubDate: 2015-02-23T07:10:53.680006-05:
      DOI: 10.1002/adfm.201570056
       
  • A Tumor Targeted Chimeric Peptide for Synergistic Endosomal Escape and
           Therapy by Dual‐Stage Light Manipulation
    • Authors: Kai Han; Qi Lei, Hui‐Zhen Jia, Shi‐Bo Wang, Wei‐Na Yin, Wei‐Hai Chen, Si‐Xue Cheng, Xian‐Zheng Zhang
      Pages: 1248 - 1257
      Abstract: In this study, a pH sensitive chimeric peptide is developed to codeliver a photosensitizer, protoporphyrin IX (PpIX), and plasmid DNA simultaneously. In the presence of matrix metalloproteinase‐2 (MMP‐2), the chimeric peptide undergoes the process of hydrolysis of PLGVR peptide sequence, exfoliation of PEG, and increase of positive charges. As a result, the chimeric peptide can be preferentially uptaken by MMP‐2 rich tumor cells. To realize synergistic effect of drug and gene delivery, a dual‐stage light irradiation strategy is developed, i.e., the short time light irradiation can efficiently enhance the endosomal escape of the chimeric peptide/PpIX/DNA complexes by the formation the reactive oxygen species (ROS), resulting in synergistic endosomal escape and improved DNA expression. In addition, due to the screened phototoxicity of PpIX, short time light irradiation does not lead to detectable changes in the cell viability. After the gene transfection, the screened phototoxicity of PpIX is subsequently stimulated by long time irradiation to achieve high synergistic efficacy of photodynamic and gene therapies. Both in vitro and in vivo studies confirm the chimeric peptide‐based nanocarrier with a good synergistic effect is a promising nanoplatform for tumor treatments. A MMP‐2 responsiveness chimeric peptide is reported to transport the photosensitizer PpIX and DNA to the target cells. Importantly, a dual‐stage light irradiation strategy is used to enhance the endosome escape via photochemical internalization. A high therapeutic index is achieved due to the synergistic effect between gene therapy and photodynamic therapy.
      PubDate: 2015-01-13T10:06:15.682941-05:
      DOI: 10.1002/adfm.201403190
       
  • Superparamagnetic Liposomes for MRI Monitoring and External Magnetic
           Field‐Induced Selective Targeting of Malignant Brain Tumors
    • Authors: Hélène Marie; Laurent Lemaire, Florence Franconi, Sonia Lajnef, Yves‐Michel Frapart, Valérie Nicolas, Ghislaine Frébourg, Michael Trichet, Christine Ménager, Sylviane Lesieur
      Pages: 1258 - 1269
      Abstract: Magnetic‐fluid‐loadedliposomes (MFLs) of optimized magnetic responsiveness are newly worked out from the entrapment of superparamagnetic maghemite nanocrystals in submicronic PEG‐ylated rhodamine‐labelled phospholipid vesicles. This nanoplatform provides an efficient tool for the selective magnetic targeting of malignant tumors localized in brain and non‐invasive traceability by MRI through intravascular administration. As assessed by in vivo 7‐T MRI and ex vivo electron spin resonance, 4‐h exposure to 190‐T m–1 magnetic field gradient efficiently concentrates MFLs into human U87 glioblastoma implanted in the striatum of mice. The magnetoliposomes are then longer retained therein as checked by MRI monitoring over a 24‐h period. Histological analysis by confocal fluorescence microscopy confirms the significantly boosted accumulation of MFLs in the malignant tissue up to the intracellular level. Electron transmission microscopy reveals effective internalization by endothelial and glioblastoma cells of the magnetically conveyed MFLs as preserved vesicle structures. The magnetic field gradient emphasizes MFL distribution solely in the tumors according to the enhanced permeability and retention (EPR) effect while comparatively very low amounts are recovered in the other cerebral areas. Such a selective targeting precisely traceable by MRI is promising for therapeutic applications since the healthy brain tissue can be expected to be spared during treatments by deleterious anticancer drugs carried by magnetically guided MFLs. Long‐circulating lipid vesicles entrapping highly concentrated superparamagnetic nanocrystals of maghemite (MFLs) provide a reliable MRI traceable tool for systemic targeting of intracerebral tumors. As experienced here on human glioblastomas implanted in the striatum of mice, the application of a magnetic field gradient significantly and selectively accumulates MFLs in the malignant neoplasms up to the intracellular level, while sparing healthy brain tissues.
      PubDate: 2015-01-14T07:11:53.758989-05:
      DOI: 10.1002/adfm.201402289
       
  • DNA/Tannic Acid Hybrid Gel Exhibiting Biodegradability, Extensibility,
           Tissue Adhesiveness, and Hemostatic Ability
    • Authors: Mikyung Shin; Ji Hyun Ryu, Joseph P. Park, Keumyeon Kim, Jae Wook Yang, Haeshin Lee
      Pages: 1270 - 1278
      Abstract: DNA has emerged as a novel material in many areas of materials science due to its programmability. Especially, DNA hydrogels have been studied to incorporate new functions into gels. To date, only a few methods have been developed for fabricating DNA hydrogels, such as the use of complementary sequences or covalent bond. Herein, it is demonstrated that one of the most well‐known plant‐derived polyphenols, tannic acid (TA), can form a DNA hydrogel which is named TNA hydrogel (TA + DNA). TA plays a role as a “molecular glue” by a new mode of action reversibly connecting between phosphodiester bonds, which is different from the crosslinking utilizing complementary sequences. TA intrinsically degrades due to ester bonds connecting between pyrogallol groups, causing a degradable DNA hydrogel. Furthermore, TNA gel is multifunctional in that the gel is extensible upon pulling and adhesive to tissues because of the rich polyphenol groups in TA (ten phenols per TA). Unexpectedly, TNA gel exhibits superior in vivo hemostatic ability that can be useful for biomedical applications. This new DNA hydrogel preparation method represents a new technique for fabricating a large amount of DNA‐based hemostatic hydrogel without chemically modifying DNA or requiring the crosslinking by complementary sequences. A new concept in DNA gel preparation using a plant‐inspired “molecular glue,” tannic acid (TA), is applied in this study. The gel, named TNA (TA + DNA) hydrogel, exhibits unique characteristics not observed in conventional DNA gels: extensibility, adhesiveness, degradability, and hemostatic ability. The crosslinking mechanism via hydrogen bonds enables the large‐scale preparation of TNA gel and the release of encapsulated DNA.
      PubDate: 2015-01-16T07:20:32.505611-05:
      DOI: 10.1002/adfm.201403992
       
  • Engineered Proteinticles for Targeted Delivery of siRNA to Cancer Cells
    • Authors: Eun Jung Lee; So Jin Lee, Yoon‐Sik Kang, Ju Hee Ryu, Koo Chul Kwon, Eunji Jo, Ji Young Yhee, Ick Chan Kwon, Kwangmeyung Kim, Jeewon Lee
      Pages: 1279 - 1286
      Abstract: Considering the problems of small interfering RNA (siRNA) delivery using traditional viral and nonviral vehicles, a new siRNA delivery system to enhance efficiency and safety needs to be developed. Here human ferritin‐based proteinticles are genetically engineered to simultaneously display various functional peptides on the surface of proteinticles: cationic peptide to capture siRNA, tumor cell targeting and penetrating peptides, and enzymatically cleaved peptide to release siRNA inside tumor cell. In the in vitro treatment of poly‐siRNA‐proteinticle complex, both of the tumor cell targeting and penetrating peptides are important for efficient delivery of siRNA, and the red fluorescent protein (RFP) expression in RFP‐expressing tumor cells is notably suppressed by the delivered siRNA with the complementary sequence to RFP mRNA. It seems that the human ferritin‐based proteinticle is an efficient, stable, and safe tool for siRNA delivery, having a great potential for application to in vivo cancer treatment. The unique feature of proteinticles is that multiple and functional peptides can be simultaneously and evenly placed and also easily switched on the proteinticle surface through a simple genetic modification, which is likely to make proteinticles appropriate for targeted delivery of siRNA to a wide range of cancer cells. An efficient system for targeted siRNA delivery to cancer cells is successfully developed using genetically engineered human ferritin‐based proteinticles. The engineered proteinticles display various functional peptides [cationic peptide to capture siRNA, tumor cell targeting and penetrating peptides (CTP and CPP, respectively), and enzymatically cleaved peptide to release small interfering RNA inside tumor cell] on their surface and show no cytotoxicity.
      PubDate: 2015-01-16T02:41:48.47798-05:0
      DOI: 10.1002/adfm.201403680
       
  • Does Excess Energy Assist Photogeneration in an Organic Low‐Bandgap
           Solar Cell?
    • Authors: Tobias Hahn; Johannes Geiger, Xavier Blase, Ivan Duchemin, Dorota Niedzialek, Steffen Tscheuschner, David Beljonne, Heinz Bässler, Anna Köhler
      Pages: 1287 - 1295
      Abstract: The field dependence of the photocurrent in a bilayer assembly is measured with the aim to clarify the role of excess photon energy in an organic solar cell comprising a polymeric donor and an acceptor. Upon optical excitation of the donor an electron is transferred to the acceptor forming a Coulomb‐bound electron–hole pair. Since the subsequent escape is a field assisted process it follows that photogeneration saturates at higher electric fields, the saturation field being a measure of the separation of the electron–hole pair. Using the low bandgap polymers, PCDTBT and PCPDTBT, as donors and C60 as acceptor in a bilayer assembly it is found that the saturation field decreases when the photon energy is roughly 0.5 eV above the S1–S0 0–0 transition of the donor. This translates into an increase of the size of the electron‐hole‐pair up to about 13 nm which is close to the Coulomb capture radius. This increase correlates with the onset of higher electronic states that have a highly delocalized character, as confirmed by quantum‐chemical calculations. This demonstrates that accessing higher electronic states does favor photogeneration yet excess vibrational energy plays no role. Experiments on intrinsic photogeneration in donor photodiodes without acceptors support this reasoning. Exciton dissociation in bilayer solar cells is facilitated by exciting into higher‐lying, more delocalized excited states of the donor polymer. This is shown by measuring the field dependence of the photocurrent in PCDTBT/C60 cells and in PCPDTBT/C60 cells for different excitation energies and comparing this to the delocalization of the associated excited states as determined by quantum‐chemical calculations.
      PubDate: 2015-01-16T02:41:35.368787-05:
      DOI: 10.1002/adfm.201403784
       
  • In‐Plane Alignment in Organic Solar Cells to Probe the Morphological
           Dependence of Charge Recombination
    • Authors: Omar Awartani; Michael W. Kudenov, R. Joseph Kline, Brendan T. O'Connor
      Pages: 1296 - 1303
      Abstract: Bulk heterojunction (BHJ) organic solar cells are fabricated with the polymer semiconductor aligned in the plane of the film to probe charge recombination losses associated with aggregates characterized by varying degrees of local order. 100% uniaxial strain is applied on ductile poly(3‐hexylthiophene):phenyl‐C61‐butyric acid methyl ester (P3HT:PCBM) BHJ films and characterize the resulting morphology with ultraviolet‐visible absorption spectroscopy and grazing incidence X‐ray diffraction. It is found that the strained films result in strong alignment of the highly ordered polymer aggregates. Polymer aggregates with lower order and amorphous regions also align but with a much broader orientation distribution. The solar cells are then tested under linearly polarized light where the light is selectively absorbed by the appropriately oriented polymer, while maintaining a common local environment for the sweep out of photogenerated charge carriers. Results show that charge collection losses associated with a disordered BHJ film are circumvented, and the internal quantum efficiency is independent of P3HT local aggregate order near the heterojunction interface. Uniquely, this experimental approach allows for selective excitation of distinct morphological features of a conjugated polymer within a single BHJ film, providing insight into the morphological origin of recombination losses. The internal quantum efficiency for light absorption in high‐order and low‐order P3HT aggregates is measured in a single photovoltaic cell, enabled by fabricating devices with polymer in‐plane alignment and selective polymer excitation using linearly polarized illumination. The internal quantum efficiency is independent of polarized illumination suggesting losses in disordered films are solely due to charge collection losses.
      PubDate: 2015-01-21T05:04:15.332972-05:
      DOI: 10.1002/adfm.201403377
       
  • Enhanced Specificity in Capturing and Restraining Circulating Tumor Cells
           with Dual Antibody–Dendrimer Conjugates
    • Authors: Jingjing Xie; Yusheng Lu, Haiyan Dong, Rongli Zhao, Hongning Chen, Weiyu Shen, Patrick J. Sinko, Yewei Zhu, Jichuang Wang, Jingwei Shao, Yu Gao, Fangwei Xie, Lee Jia
      Pages: 1304 - 1313
      Abstract: Specifically capturing and restraining residual circulating tumor cells (CTCs) in cancer patients are the sine qua non for safely and effectively preventing cancer metastasis, to which the current chemotherapy has been limited due to its toxicity. Moreover, because of CTCs’ rarity and low activity, the current technology for capturing CTCs based solely on a single surface biomarker has limited capacity and is used mainly for in vitro diagnosis. Here, it is possible to sequentially conjugate two CTCs antibodies (aEpCAM and aSlex) to the functionalized dendrimers to specifically capture human hepatocellular CTCs in both artificial and clinical patient blood samples, and restrain their activities. The molecular entities of the conjugates are demonstrated by various means. The dual antibody conjugate captured CTCs threefold more than the single counterparts from the high concentrations of interfering red blood cells or leukocytes, as well as from the blood of liver cancer patients, and exhibits the superiority to their single counterparts in down‐regulating the captured CTCs. These results collectively provide the strong evidence that two antibodies can be compatibly conjugated to a nanomaterial, resulting in an enhanced specificity in restraining CTCs in blood. Synthesized dual antibody‐coated nanomaterial conjugates can specifically capture the rare circulating HepG2 tumor cells mixed with large population of red blood cells and HL‐60, resulting in down‐regulation of HepG2.
      PubDate: 2015-01-21T05:04:43.410473-05:
      DOI: 10.1002/adfm.201403556
       
  • Gold Nanoclusters‐Based Nanoprobes for Simultaneous Fluorescence
           Imaging and Targeted Photodynamic Therapy with Superior Penetration and
           Retention Behavior in Tumors
    • Authors: Chunlei Zhang; Chao Li, Yanlei Liu, Jingpu Zhang, Chenchen Bao, Shujing Liang, Qing Wang, Yao Yang, Hualin Fu, Kan Wang, Daxiang Cui
      Pages: 1314 - 1325
      Abstract: Gold nanoclusters (GNCs) attract increasing attention due to their potential applications in sensing, catalysis, optoelectronics, and biomedicine. Herein, the formation of highly fluorescent glutathione (GSH)‐capped GNCs is achieved through the delicate control of the reduction kinetics and thermodynamic selection of the Au(I)–SG complexes. Furthermore, the GNCs‐based nanoprobes are developed by the covalent coupling folic acid (FA) and PEG (polyethylene glycol) on the surface of GNCs directly, followed by trapping photosensitizer (chlorin e6, Ce6) within PEG networks and attaching to the GNCs surface. The fabricated nanoprobes (Ce6@GNCs‐PEG2K‐FA) possess a uniform particle size (hydrodynamic diameter ≈6.1 ± 1.2 nm), without affecting the yield of singlet oxygen of the trapped Ce6. In vitro studies show the enhanced cellular uptake and satisfactory photodynamic therapy (PDT) effectiveness toward MGC‐803 cells when compared with free Ce6. The biodistribution and excretion pathway studies of the nanoprobes in MGC‐803 tumor‐bearing nude mice reveal their superior penetration and retention behavior in tumors, while the preserved features of renal clearance and stealthy to reticulo‐endothelial system are mainly attributed to the small hydrodynamic diameters and the FA‐capped PEGylated ligands. The enhanced PDT efficacy and the nontoxicity to mice provide an exciting new nano‐platform with promising clinical translational potential. A novel gold nanoclusters‐based Ce6 delivery nano‐platform is developed to achieve selective targeting toward cancer cells and tumors combining photodynamic therapy therapy. Systematic in vitro and in vivo experiments evaluate the cellular uptake, light‐induced cell apoptosis, biodistribution, as well as FA‐directed active tumor targeting and deep‐penetration‐enhanced photodynamic therapy of the gold nanoclusters‐based nanoprobes. The results identify the great potentials of gold nanoclusters for clinical use.
      PubDate: 2015-01-16T07:21:18.231039-05:
      DOI: 10.1002/adfm.201403095
       
  • Drug Delivery: Enzyme‐Responsive Release of Doxorubicin from
           Monodisperse Dipeptide‐Based Nanocarriers for Highly Efficient
           Cancer Treatment In Vitro (Adv. Funct. Mater. 8/2015)
    • Authors: He Zhang; Jinbo Fei, Xuehai Yan, Anhe Wang, Junbai Li
      Pages: 1327 - 1327
      Abstract: Cationic diphenylalanine can self‐assemble into biocompatible and biodegradable nanoparticles through cross‐linkage of glutaraldehyde. As shown by X. Yan, J. Li, and colleagues on page 1193, such assembled nanoparticles have a typical enzyme‐responsive characterization and can be employed as nanocarriers for drug delivery. The doxorubicin‐loaded nanocarriers with a lower drug concentration still possess a higher efficiency in killing cancer cells.
      PubDate: 2015-02-23T07:11:01.864176-05:
      DOI: 10.1002/adfm.201570057
       
  • Fluorine: Edge‐Fluorinated Graphene Nanoplatelets as High
           Performance Electrodes for Dye‐Sensitized Solar Cells and Lithium
           Ion Batteries (Adv. Funct. Mater. 8/2015)
    • Authors: In‐Yup Jeon; Myung Jong Ju, Jiantie Xu, Hyun‐Jung Choi, Jeong‐Min Seo, Min‐Jung Kim, In Taek Choi, Hong Mo Kim, Jae Cheon Kim, Jae‐Joon Lee, Hua Kun Liu, Hwan Kyu Kim, Shixue Dou, Liming Dai, Jong‐Beom Baek
      Pages: 1328 - 1328
      Abstract: Edge‐selectively fluorinated graphene nanoplatelets (FGnPs) are produced by H. K. Kim, S. Dou, L. Dai, J.‐B. Baek, and co‐workers on page 1170 by unzipping graphitic framework in the presence of diluted fluorine gas (green color). Due to the formation of the most stable C–F bonds at the edges, the FGnPs show the profoundly enhanced electrochemical performance in DSSCs and LIBs with excellent cycling stability.
      PubDate: 2015-02-23T07:10:55.151007-05:
      DOI: 10.1002/adfm.201570058
       
  • Discotic Liquid Crystal‐Functionalized Gold Nanorods: 2‐ and
           3D Self‐Assembly and Macroscopic Alignment as well as Increased
           Charge Carrier Mobility in Hexagonal Columnar Liquid Crystal Hosts
           Affected by Molecular Packing and π–π Interactions
    • Authors: Xiang Feng; Lydia Sosa‐Vargas, S. Umadevi, Taizo Mori, Yo Shimizu, Torsten Hegmann
      Pages: 1180 - 1192
      Abstract: Gold nanorods functionalized with triphenylene‐based discotic liquid crystal (LC) motifs show striking self‐assembly behavior both on transmission electron microscopy (TEM) grids as well as in the bulk enforced by the π–π‐stacking of triphenylene groups of adjacent nanorods. TEM images confirm that these discotic LC nanorods form ribbons of parallel‐stacked nanorods several hundred nanometer long. The pursued silane conjugation approach to decorate the nanorods allows for the preparation of dispersions of the nanorods in the hexagonal columnar phases of parent discotic LCs, where the nanorods can be macroscopically aligned with almost 80% efficiency by a simple shearing protocol. Doping the parent host materials with about 1% by weight of the discotic LC‐capped nanorods also reduces the lattice parameter and the intracolumnar packing, which gives rise to enhanced charge carrier mobility in these hosts as determined by time‐of‐flight measurements. Tiny amount, big effect: Gold nanorods capped with discotic liquid crystal motifs self‐assemble into nanorod ribbons several hundred nanometer long, and can be macroscopically aligned in the parent discotic liquid crystal. At only 1% by weight, these nanorods affect the packing of the host phase leading to an increase in charge carrier mobility in the columnar phase.
      PubDate: 2014-12-17T08:56:39.274178-05:
      DOI: 10.1002/adfm.201401844
       
  • Enzyme‐Responsive Release of Doxorubicin from Monodisperse
           Dipeptide‐Based Nanocarriers for Highly Efficient Cancer Treatment
           In Vitro
    • Authors: He Zhang; Jinbo Fei, Xuehai Yan, Anhe Wang, Junbai Li
      Pages: 1193 - 1204
      Abstract: Small aldehyde molecule are demonstrated to induce cationic diphenylalanine to assemble into monodisperse enzyme‐responsive nanocarriers with high biocompatibility and excellent biodegradability. The formation of Schiff base covalent bond and accompanying π–π interaction of aromatic rings are found to be the mainly driving forces for the assembly of the nanocarriers. Interestingly, the nanocarriers show autofluorescence due to the n–π* transitions of C = N bonds, which lends them visually traceable property in living cells. Importantly, the nanocarriers can be taken in by cells and biodegraded in the cells. In addition, doxorubicin is easily loaded into the nanocarriers with high encapsulation amount, and its release can be triggered by tyrisin under physiological conditions. Noticeably, even at a very low drug concentration, the doxorubicin‐loaded nanocarriers still exhibit a much higher killing capacity of HeLa cells in vitro, compared to the equivalent‐dose free doxorubicin, indicating they have a great potential biomedical application. Cationic diphenylalanine (CDP) can assemble into biocompatible and biodegradable nanocarriers through cross‐linkage of glutaraldehyde (GA). The nanocarriers can be biodegraded under the action of tyrisin. Importantly, after being loaded with doxorubicin (DOX) the nanocarriers also show a desired enzyme‐responsive property, and the release of DOX can be easily achieved in PBS (pH 7.2) with tyrisin.
      PubDate: 2014-11-20T03:11:04.840331-05:
      DOI: 10.1002/adfm.201403119
       
  • Liquid‐Crystalline Electrolytes for Lithium‐Ion Batteries:
           Ordered Assemblies of a Mesogen‐Containing Carbonate and a Lithium
           Salt
    • Authors: Junji Sakuda; Eiji Hosono, Masafumi Yoshio, Takahiro Ichikawa, Takuro Matsumoto, Hiroyuki Ohno, Haoshen Zhou, Takashi Kato
      Pages: 1206 - 1212
      Abstract: Thermotropic liquid‐crystalline (LC) electrolytes for lithium‐ion batteries are developed for the first time. A rod‐like LC molecule having a cyclic carbonate moiety is used to form self‐assembled two‐dimensional ion‐conductive pathways with lithium salts. Electrochemical and thermal stability, and efficient ionic conduction is achieved for the liquid crystal. The mixture of the carbonate derivative and lithium bis(trifluoromethylsulfonyl)imide is successfully applied as an electrolyte in lithium‐ion batteries. Reversible charge–discharge for both positive and negative electrodes is observed for the lithium‐ion batteries composed of the LC electrolyte. A thermotropic liquid‐crystalline (LC) electrolyte for lithium‐ion batteries is developed. The LC electrolyte is successfully used for lithium‐ion batteries. The electrolyte is a mixture of a carbonate‐based rod‐like molecule and lithium bis(trifluoromethylsulfonyl)imide. This is the first demonstration of the applicability of thermotropic LC electrolytes to lithium‐ion batteries.
      PubDate: 2014-12-22T06:17:33.700504-05:
      DOI: 10.1002/adfm.201402509
       
  • Electronic Structures and Photoconversion Mechanism in
           Perovskite/Fullerene Heterojunctions
    • Authors: Ming‐Fai Lo; Zhi‐Qiang Guan, Tsz‐Wai Ng, Chiu‐Yee Chan, Chun‐Sing Lee
      Pages: 1213 - 1218
      Abstract: It has been generally believed and assumed that organometal halide perovskites would form type II P–N junctions with fullerene derivatives (C60 or PCBM), and the P–N junctions would provide driving force for exciton dissociation in perovskite‐based solar cell. To the best of our knowledge, there is so far no experiment proof on this assumption. On the other hand, whether photogenerated excitons can intrinsically dissociate into free carrier in the perovskite without any assistance from a P–N junction is still controversial. To address these, the interfacial electronic structures of a vacuum‐deposited perovskite/C60 and a solution‐processed perovskite/PCBM junctions is directly measured by ultraviolet photoelectron spectroscopy. Contrary to the common believes, both junctions are found to be type I N–N junctions with band gap of the perovskites embedded by that of the fullerenes. Meanwhile, device with such a charge inert junction can still effectively functions as a solar cell. These results give direct experimental evidence that excitons are dissociated to free carriers in the perovskite film even without any assistance from a P–N junction. While perovskites/fullerene is commonly assumed to form a type II P–N junction with its internal E‐field facilitating exciton dissociation, it is found that perovskite/C60 (PCBM) is a charge inert type I N–N junction. Devices with such a junction show photovoltaic effects effectively, thus photogenerated excitons can indeed dissociate to free carriers in the perovskite film.
      PubDate: 2014-12-28T15:38:59.115808-05:
      DOI: 10.1002/adfm.201402692
       
  • Highly Fluorescent Thienoviologen‐Based Polymer Gels for Single
           Layer Electrofluorochromic Devices
    • Authors: Amerigo Beneduci; Sante Cospito, Massimo La Deda, Giuseppe Chidichimo
      Pages: 1240 - 1247
      Abstract: A highly fluorescent electrofluorochromic gel with quantum yields as high as 67% is prepared by incorporating the thienoviologen fluorophore 4,4′‐(2,2′‐bithiophene‐5,5′‐diyl)bis(1‐nonylpridinium)bistriflimide into a polymeric matrix. The fluorescent emission spectrum of the gel at low percentages of thienoviologen shows a strong band at 530 nm. A new intense fluorescence band at 630 nm can be induced by fluorophore aggregation. Single layer electrofluorochromic devices were readily prepared by sandwiching the polymer gels between two indium tin oxide (ITO) electrodes. The fluorescence intensity can be easily modulated between a fluorescent and a quenched state, in a wide visible spectral range, by direct electrochemical reduction of the thienoviologen fluorophore. It exhibits three reduction states, each with different emission properties. The reversible interconversion among these states leads to a high electrofluorochromic stability of the device, exhibiting switching times of a few seconds and, to the best of our knowledge, the highest contrast ratio (337). A single layer ITO/EFC/ITO device is presented where the electrofluorochromic layer is a polymer gel containing the fluorescent thienoviologen dication 4,4′‐(2,2′‐bithiophene‐5,5′‐diyl)bis(1‐nonylpridinium). Its reduction allows to switch the fluorescence between a high fluorescence off state and a quenched on state in the 470–800 nm spectral range. This device exhibits high fluorescence contrasts, short switching times, and a high cycling lifetime.
      PubDate: 2014-12-16T11:05:54.535273-05:
      DOI: 10.1002/adfm.201403611
       
 
 
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