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CHEMISTRY (570 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: 362)
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: 39)
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: 17)
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: 5)
AMB Express     Open Access  
Ambix     Hybrid Journal   (Followers: 2)
American Journal of Applied Sciences     Open Access   (Followers: 31)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 216)
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: 37)
Angewandte Chemie     Hybrid Journal   (Followers: 18)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 274)
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: 21)
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: 7)
Biochemistry     Full-text available via subscription   (Followers: 273)
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: 2)
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)

        1 2 3 4 5 6 | Last

Journal Cover   Advanced Functional Materials
  [SJR: 4.682]   [H-I: 156]   [41 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  [1611 journals]
  • Pseudobinary Solid‐Solution: An Alternative Way for the Bandgap
           Engineering of Semiconductor Nanowires in the Case of GaP–ZnSe
    • Authors: Wenjin Yang; Baodan Liu, Bing Yang, Jianyu Wang, Takashi Sekiguchi, Staedler Thorsten, Xin Jiang
      Pages: n/a - n/a
      Abstract: Bandgap engineering of semiconductor nanostructures is of significant importance either for the optical property tailoring or for the integration of functional optoelectronic devices. Here, an efficient way to control the bandgap and emission wavelength is reported for a binary compound semiconductor through alloying with another binary compound. Taking GaP‐ZnSe system as an example, the bandgap of quaternary GaP‐ZnSe solid‐solution nano­wires can be selectively tailored in the range of 1.95–2.2 eV by controlling the solubility of ZnSe dopants in GaP host. High‐resolution transmission electron microscopy measurement and chemical analyses using an X‐ray energy dispersive spectrometer (EDS) demonstrate the solid‐solution feature of GaP‐ZnSe semiconductor alloy, while X‐ray photoelectron spectroscopy (XPS) characterization verifies the formation of some new chemical bonds corresponding to Zn‐P and Ga‐S bonds in GaP‐ZnSe nanowires. The strategy to tailor the optoelectronic property of semiconductor nanostructures through the solid‐solution of two different binary compounds represents a general routine to the property modification of all pseudobinary systems and will open more opportunity for their applications in electronics, optics and optoelectronics. GaP–ZnSe quaternary solid‐solution nanowires with different ZnSe ratios have been achieved through a multichannel chemical vapor deposition method. Cathodoluminescence measurements demonstrate that the bandgap of GaP–ZnSe solid‐solution can be tailored in the range of 1.95–2.2 eV by tuning the ZnSe concentrations. The solid‐solution of different binary semiconductor compounds provides an efficient way for modulating optoelectronic properties.
      PubDate: 2015-03-16T08:28:34.439537-05:
      DOI: 10.1002/adfm.201404523
  • Porous Gold with a Nested‐Network Architecture and Ultrafine
    • Authors: Zhen Qi; Ulla Vainio, Andreas Kornowski, Martin Ritter, Horst Weller, Haijun Jin, Jörg Weissmüller
      Pages: n/a - n/a
      Abstract: A preparation strategy is developed for monolithic samples of nanoporous gold with a hierarchical structure comprising two nested networks of solid “ligaments” on distinctly different structural length scales. The electrochemical dealloying protocol achieves a large retention of less noble element in a first corrosion step, thereby allowing an extra corrosion step which forms a separate structural hierarchy level. The beneficial impact of adding Pt to the Ag–Au master alloys that are more conventionally used in dealloying approaches to nanoporous gold is demonstrated. At ≈6 nm, the lower hierarchy level ligament size emerges extremely small. Furthermore, Pt favors the retention of Ag during the first dealloying step even when the master alloy has a high Au content. The high Au content reduces the corrosion‐induced shrinkage, mitigating crack formation during preparation and favoring the formation of high‐quality macroscopic (mm‐sized) samples. The corrosion effectively carves out the nanoscale hierarchical ligament structure from the parent crystals tens of micrometers in size. This is revealed by X‐ray as well as electron backscatter diffraction, which shows that the porous crystallites inherit the highly ordered, macroscopic crystal lattice structure of the master alloy. Nanoporous gold with a hierarchical structure comprises highly ordered and geometrically similar metal networks nested on two distinctly different size scales. The underlying electrochemical dealloying protocol allows two separate corrosion steps, successively carving the two hierarchy levels from the parent crystal. Using Ag‐Au‐Pt master alloys brings a lower level size of 6 nm in crack‐free monolithic porous bodies.
      PubDate: 2015-03-16T08:11:37.909451-05:
      DOI: 10.1002/adfm.201404544
  • The Relationship between Structural and Electrical Characteristics in
           Perylenecarboxydiimide‐Based Nanoarchitectures
    • Authors: Chiara Musumeci; Ingo Salzmann, Sara Bonacchi, Christian Röthel, Steffen Duhm, Norbert Koch, Paolo Samorì
      Pages: n/a - n/a
      Abstract: The controlled assembly of the prototypical n‐type organic semiconductor N,N′‐1H,1H‐perfluorobutyl dicyanoperylenecarboxydiimide (PDIF‐CN2) into ordered nanoarchitectures and the multiscale analysis of the correlation between their structural and their electrical properties is reported. By making use of the Langmuir–Blodgett (LB) technique, monolayers of PDIF‐CN2 arranged in upright standing molecular packing on different substrates are formed. Postdeposition thermal treatment makes it possible to trigger a reorganization into layered ultrathin crystalline nanostructures, exhibiting structural and photophysical properties similar to those of microscopic crystals obtained by solvent‐induced precipitation. The controlled engineering of these molecular architectures on surfaces enables us to identify both a dependence of the monolayer resistance on the molecular tilt angle in vertical junctions and a pronounced charge‐transport anisotropy with enhanced transport along the π–π stacking direction of the PDI core. While a charge carrier mobility for electrons as high as 10–2 cm2 V–1 s–1 is determined in monolayer field‐effect transistors for the in‐plane direction, being the highest yet reported value for a n‐type LB monolayer, the out‐of‐plane mobility measured by conductive atomic force microscopy in multilayered structures is found to be one order of magnitude lower. The multiscale correlation between structural and electrical properties of a prototypical n‐type organic semiconductor assembled in different ordered nanoarchitectures, from Langmuir–Blodgett (LB) monolayer films to few monolayers‐thin structures, is performed. The highest charge carrier mobility yet reported for a n‐type LB monolayer is obtained, being one order of magnitude higher than the out‐of‐plane mobility measured in the multilayered structures, evidencing charge‐transport anisotropy.
      PubDate: 2015-03-16T08:07:45.230862-05:
      DOI: 10.1002/adfm.201403773
  • Electrical Transport and Oxygen Exchange in the Superoxides of Potassium,
           Rubidium, and Cesium
    • Authors: Oliver Gerbig; Rotraut Merkle, Joachim Maier
      Pages: n/a - n/a
      Abstract: Conductivity, ionic transference number, and chemical diffusion coefficients are determined for KO2, RbO2, and CsO2. Based on such results, a defect‐chemical model is constructed. These superoxides are found to exhibit a total conductivity in the range of 3 × 10–7 to 5 × 10–5 S cm–1 at 200 °C with contributions from ionic and electronic carriers. The ionic conductivity is caused by alkali interstitials and superoxide vacancies as mobile defects, and is found to exceed the n‐type electronic conductivity. 18O isotope exchange on powder samples (monitoring the gas phase composition) shows that essentially all oxygen can be exchanged. At high pO2 this largely occurs without breaking of the O–O bond—indicating a sufficient mobility of molecular superoxide species in the solid—and with an effective rate constant that is much higher than for other large‐bandgap mixed conducting materials such as SrTiO3. Alkali superoxides KO2,RbO2, CsO2 exhibit mixed ionic/electronic conductivity (σtot = 3 × 10–7–5 × 10–6 S cm–1 at 200 °C). Superoxide ions O2− can migrate without dissociation, and the oxygen exchange rate with the gas phase is orders of magnitude higher compared to large bandgap perovskites such as SrTiO3.
      PubDate: 2015-03-16T08:03:42.620555-05:
      DOI: 10.1002/adfm.201404197
  • pH‐ and NIR Light‐Responsive Micelles with
           Hyperthermia‐Triggered Tumor Penetration and Cytoplasm Drug Release
           to Reverse Doxorubicin Resistance in Breast Cancer
    • Authors: Haijun Yu; Zhirui Cui, Pengcheng Yu, Chengyue Guo, Bing Feng, Tongying Jiang, Siling Wang, Qi Yin, Dafang Zhong, Xiangliang Yang, Zhiwen Zhang, Yaping Li
      Pages: n/a - n/a
      Abstract: The acquisition of multidrug resistance (MDR) is a major hurdle for the successful chemotherapy of tumors. Herein, a novel hybrid micelle with pH and near‐infrared (NIR) light dual‐responsive property is reported for reversing doxorubicin (DOX) resistance in breast cancer. The hybrid micelles are designed to integrate the pH‐ and NIR light‐responsive property of an amphiphilic diblock polymer and the high DOX loading capacity of a polymeric prodrug into one single nanocomposite. At physiological condition (i.e., pH 7.4), the micelles form compact nanostructure with particle size around 30 nm to facilitate blood circulation and passive tumor targeting. Meanwhile, the micelles are quickly dissociated in weakly acidic environment (i.e., pH ≤ 6.2) to release DOX prodrug. When exposed to NIR laser irradiation, the hybrid micelles can trigger notable tumor penetration and cytosol release of DOX payload by inducing tunable hyperthermia effect. In combination with localized NIR laser irradiation, the hybrid micelles significantly inhibit the growth of DOX‐resistant MCF‐7/ADR breast cancer in an orthotopic tumor bearing mouse model. Taken together, this pH and NIR light‐responsive micelles with hyperthermia‐triggered tumor penetration and cytoplasm drug release can be an effective nanoplatform to combat cancer MDR. Novel pH‐ and near‐infrared (NIR) light‐responsive micelles are developed to overcome doxorubicin‐resistance in breast cancer, with hyperthermia‐triggered tumor penetration and cytoplasm drug release. The micelles can be specifically dissociated in acidic intracellular organelles to release chemotherapeutic payload and induce a moderate hyperthermia effect by converting NIR light into heat. This suggests a novel approach for combating multidrug‐resistant cancers.
      PubDate: 2015-03-16T02:55:03.642337-05:
      DOI: 10.1002/adfm.201404484
  • Multiscale Assembly of Superinsulating Silica Aerogels Within Silylated
           Nanocellulosic Scaffolds: Improved Mechanical Properties Promoted by
           Nanoscale Chemical Compatibilization
    • Authors: Shanyu Zhao; Zheng Zhang, Gilles Sèbe, Rudder Wu, Raymond V. Rivera Virtudazo, Philippe Tingaut, Matthias M. Koebel
      Pages: n/a - n/a
      Abstract: Silica aerogels are amongst the lightest mesoporous solids known and well recognized for their superinsulating properties, but the weak mechanical properties of the inorganic network structure has often narrowed their field of application. Here, the inherent brittleness of dried inorganic gels is tackled through the elaboration of a strong mesoporous silica aerogel interpenetrated with a silylated nanocellulosic scaffold. To this avail, a functionalized scaffold is synthesized by freeze‐drying an aqueous suspension of nanofibrillated cellulose (NFC)—a bio‐based nanomaterial mechanically isolated from renewable resources—in the presence of methyltrimethoxysilane sol. The silylated NFC scaffold displays a high porosity (>98%), high flexibility, and reduced thermal conductivity (λ) compared with classical cellulosic structures. The polysiloxane layer decorating the nanocellulosic scaffold is exploited to promote the attachment of the mesoporous silica matrix onto the nanofibrillated cellulose scaffold (NFCS), leading to a reinforced silica hybrid aerogel with improved thermomechanical properties. The highly porous (>93%) silica‐NFC hybrids displays meso‐ and macroporosity with pore diameters controllable by the NFCS mass fraction, reduced linear shrinkage, improved compressive properties (55% and 126% increase in Young's modulus and tensile strength, respectively), while maintaining superinsulating properties (λ ≤ 20 mW (m K)–1). This study details a new direction for the synthesis of multiscale hybrid silica aerogel structures with tailored properties through the use of alkyltrialkoxysilane prefunctionalized nanocellulosic scaffolds. A strong multiscale silica aerogel is obtained through the interpenetration of silica nanoparticles with a silylated nanocellulosic scaffold. The polysiloxane layer decorating the scaffold is exploited to promote the attachment of the mesoporous silica matrix onto the nanofibrillated cellulose scaffold, leading to highly porous silica hybrid aerogel displaying reduced linear shrinkage, improved compressive properties but maintaining its superinsulating properties.
      PubDate: 2015-03-16T02:54:54.76847-05:0
      DOI: 10.1002/adfm.201404368
  • Printing Nanostructures with a Propelled Anti‐Pinning Ink Droplet
    • Authors: Gady Konvalina; Alexander Leshansky, Hossam Haick
      Pages: n/a - n/a
      Abstract: Striving for cheap and robust manufacturing processes has prompted efforts to adapt and extend methods for printed electronics and biotechnology. A new “direct‐write” printing method for patterning nanometeric species in addressable locations has been developed, by means of evaporative deposition from a propelled anti‐pinning ink droplet (PAPID) in a manner analogous to a snail‐trail. Three velocity‐controlled deposition regimes have been identified; each spontaneously produces distinct and well‐defined self‐assembled deposition patterns. Unlike other technologies that rely on overlapping droplets, PAPIDs produce continuous patterns that can be formed on rigid or flexible substrates, even within 3D concave closed shapes, and have the ability to control the thickness gradient along the pattern. This versatile low cost printing method can produce a wide range of unusual electronic systems not attainable by other methods. Lateral actuation of propelled anti‐pinning ink droplets is presented and explored as a new approach for patterning nanomaterials. This approach achieves continuous patterns that can be formed on rigid or flexible substrates, even within 3D concave closed shapes, and offers the ability to produce a controlled thickness gradient along the patterns.
      PubDate: 2015-03-16T02:54:40.711731-05:
      DOI: 10.1002/adfm.201500215
  • TAPE: A Medical Adhesive Inspired by a Ubiquitous Compound in Plants
    • Authors: Keumyeon Kim; Mikyung Shin, Mi‐Young Koh, Ji Hyun Ryu, Moon Sue Lee, Seonki Hong, Haeshin Lee
      Pages: n/a - n/a
      Abstract: Adhesives play an important role in industrial fields such as electronics, architectures, energy plantation, and others. However, adhesives used for medical purpose are rather under‐developed compared with those used in industry and consumer products. One key property required for medical adhesives is to maintain their adhesiveness in the presence of body fluid. Here, an entirely new class of medical adhesives called TAPE is reported; this is produced by intermolecular hydrogen bonding between a well‐known polyphenol compound, tannic acid, and poly(ethylene glycol). The preparation method of TAPE is extremely easy, forming a few liters at once by just the simple mixing of the two compounds without any further chemical synthetic procedures. TAPE shows a 250% increase in adhesion strength compared with fibrin glue, and the adhesion is well maintained in aqueous environments. It is demonstrated that TAPE is an effective hemostatic material and a biodegradable patch for detecting gastroesophageal reflux disease in vivo. Widespread use of TAPE is anticipated in various medical and pharmaceutical applications such as muco‐adhesives, drug depots, and others, because of its scalability, adhesion, and facile preparation. TAPE is a medical glue inspired by the adhesive properties of polyphenols and is found ubiquitously in plant species. The adhesion strength of TAPE exhibits a 250% increase relative to that of fibrin glue, and TAPE exhibits wet‐resistant adhesion. TAPE can be an effective hemostatic material and a pH‐sensitive patch for detecting gastroesophageal reflux disease in vivo.
      PubDate: 2015-03-16T02:45:20.294042-05:
      DOI: 10.1002/adfm.201500034
  • Lab in a Tube: Purification, Amplification, and Detection of DNA Using
           Poly(2‐oxazoline) Multilayers
    • Authors: Meike N. Leiske; Matthias Hartlieb, Christian Paulenz, David Pretzel, Martin Hentschel, Christoph Englert, Michael Gottschaldt, Ulrich S. Schubert
      Pages: n/a - n/a
      Abstract: Fast and easy purification and amplification of DNA are prerequisites for the development of point‐of‐care diagnostics. For this reason covalent coatings of amine containing poly(2‐oxazoline)s (POx) on glass and poly(propylene) surfaces are prepared, to reversibly bind genetic material directly from biological samples. The polymer is deposited in a layer‐by‐layer process, whereas initial immobilization of macromolecules on the surface is accomplished by the use of an epoxy functionalized siloxane monolayer. Alternating treatment with polymer and cross‐linker leads to the construction of amine containing POx multilayers on the substrates. Successful deposition is investigated by confocal laser scanning microscopy (using labeled polymers), contact angle measurements, as well as reflectometric interference spectroscopy. The interaction of these layer systems with DNA regarding binding and temperature dependent release is studied using labeled genetic material. Finally, polymerase chain reaction (PCR) vessels are coated with POx layers on the inside, and used for quantitative real‐time PCR (qPCR) experiments. It is possible to bind genetic material directly from cell lysates to perform qPCR assays from surface adsorbed DNA within the same tube including amplification, as well as detection. The presented system displays an easy to use device for a point of care diagnostic. Detection of DNA directly from biological material is performed by the use of covalently bound poly(2‐oxazoline) multilayers on polypropylene. Layer‐by‐layer assembly and interaction with genetic material is investigated in detail, and the amplification and detection of surface adsorbed DNA is performed by quantitative real‐time polymerase chain reaction using coated reaction vessels.
      PubDate: 2015-03-16T02:45:12.969826-05:
      DOI: 10.1002/adfm.201404510
  • Self‐Repairable, High Permittivity Dielectric Elastomers with Large
           Actuation Strains at Low Electric Fields
    • Authors: Simon J. Dünki; Yee Song Ko, Frank A. Nüesch, Dorina M. Opris
      Pages: n/a - n/a
      Abstract: A one‐step process for the synthesis of elastomers with high permittivity, excellent mechanical properties and increased electromechanical sensitivity is presented. It starts from a high molecular weight polymethylvinylsiloxane, P1, whose vinyl groups serve two functions: the introduction of polar nitrile moieties by reacting P1 with 3‐mercaptopropionitrile (1) and the introduction of cross‐links to fine tune mechanical properties by reacting P1 with 2,2′‐(ethylenedioxy)diethanethiol (2). This twofold chemical modification furnished a material, C2, with a powerful combination of properties: permittivity of up to 10.1 at 104 Hz, elastic modulus Y10% = 154 kPa, and strain at break of 260%. Actuators made of C2 show lateral actuation strains of 20.5% at an electric field as low as 10.8 V μm–1. Additionally, such actuators can self‐repair after a breakdown, which is essential for an improved device lifetime and an attractive reliability. The actuators can be operated repeatedly and reversibly at voltages below the first breakdown. Due to the low actuation voltage and the large actuation strain applications of this material in commercial products might become reality. A one‐step process is presented for the synthesis of dielectric elastomers with permittivity of up to 10.1 at 10 kHz, Y(10%) = 154 kPa, and strain at break of 260%. Actuators made with them are able to self‐repair after a breakdown and show lateral strains of up to 20.5% at an electric field as low as 10.8 V µm–1.
      PubDate: 2015-03-16T02:45:05.804396-05:
      DOI: 10.1002/adfm.201500077
  • A Novel Bioinspired Switchable Adhesive with Three Distinct Adhesive
    • Authors: Paula Yagüe Isla; Elmar Kroner
      Pages: n/a - n/a
      Abstract: A novel switchable adhesive, inspired by the gecko's fibrillar dry attachment system, is introduced. It consists of a patterned surface with an array of mushroom‐shaped pillars having two distinct heights. The different pillar heights allow control of the pull‐off force in two steps by application of a low and a high preload. For low preload, only the long pillars form contact, resulting in a low pull‐off force. At higher preload, all pillars form contact, resulting in high pull‐off force. Even further loading leads to buckling induced detachment of the pillars which corresponds to extremely low pull‐off force. To achieve the respective samples a new fabrication method called double inking is developed, to achieve multiple‐height pillar structures. The adhesion performance of the two‐step switchable adhesive is analysed at varying preload and for different pillar aspect ratios and height relations. Finally, the deformation behavior of the samples is investigated by in situ monitoring. Novel bioinspired, switchable adhesives with pillars of different length have been successfully prepared, and allow control of the pull‐off force by means of preloading. Three distinct adhesive states are accessible. Adhesive properties are characterized by force–distance experiments and in situ observation of the deformation. Various applications, for example, in transportation, handling, and robotics, may benefit from the new bioinspired adhesive.
      PubDate: 2015-03-16T02:45:00.053554-05:
      DOI: 10.1002/adfm.201500241
  • When Nanoparticles Meet Poly(Ionic Liquid)s: Chemoresistive CO2 Sensing at
           Room Temperature
    • Authors: Christoph Willa; Jiayin Yuan, Markus Niederberger, Dorota Koziej
      Pages: n/a - n/a
      Abstract: Tetraalkylammonium‐based poly(ionic liquid)s (PILs) are able to absorb particularly large amounts of CO2; thus are considered up‐and‐coming materials in applications ranging from sensing, separation, to storage of CO2. To meet the requirements of practical usage, their chemical activity has to be combined with other functionalities, for example, by fabricating composite materials. Poly[(p‐vinylbenzyl)trimethylammonium hexafluorophosphate] and La2O2CO3 nanoparticles—both of which are intrinsically insulating materials— are utilized as building blocks, taking full advantage of the electrostatic interaction at their interface to boost the overall conductivity of composites at room temperature. To rationalize this unique behavior, the charge transport mechanism is studied using impedance spectroscopy. It is found find that, for the composites with La2O2CO3 content of 60–80 wt%, the interfacial effect becomes dominant and leads to the formation of conduction channels with increased mobility of [PF6]− anions. These composites show further increase of the conductivity when exposed to pulses of CO2 between 150 and 2400 ppm at room temperature in a relative humidity of 50%. This work therefore provides a simple strategy to achieve an enhancement of the electrical properties required for the utilization of PILs‐based CO2 sensors, but in the future this concept can be easily extended to other electronic devices. Poly(ionic liquid)‐based CO2 chemoresistive sensors are fabricated by applying a simple strategy to achieve an enhancement of the electrical properties. Advantage is taken of the electrostatic interaction at the interface between La2O2CO3 nanoparticles and poly[(p‐vinylbenzyl)trimethylammonium hexafluorophosphate] to boost the overall conductivity of composites at room temperature. To rationalize this unique behavior, the charge transport mechanism using impedance spectroscopy is studied.
      PubDate: 2015-03-16T02:44:34.308204-05:
      DOI: 10.1002/adfm.201500314
  • Vinylogous Urethane Vitrimers
    • Authors: Wim Denissen; Guadalupe Rivero, Renaud Nicolaÿ, Ludwik Leibler, Johan M. Winne, Filip E. Du Prez
      Pages: n/a - n/a
      Abstract: Vitrimers are a new class of polymeric materials with very attractive properties, since they can be reworked to any shape while being at the same time permanently cross‐linked. As an alternative to the use of transesterification chemistry, we explore catalyst‐free transamination of vinylogous urethanes as an exchange reaction for vitrimers. First, a kinetic study on model compounds reveals the occurrence of transamination of vinylogous urethanes in a good temperature window without side reactions. Next, poly(vinylogous urethane) networks with a storage modulus of ≈2.4 GPa and a glass transition temperature above 80 °C are prepared by bulk polymerization of cyclohexane dimethanol bisacetoacetate, m‐xylylene diamine, and tris(2‐aminoethyl)amine. The vitrimer nature of these networks is examined by solubility, stress‐relaxation, and creep experiments. Relaxation times as short as 85 s at 170 °C are observed without making use of any catalyst. In addition, the networks are recyclable up to four times by consecutive grinding/compression molding cycles without significant mechanical or chemical degradation. Catalyst‐free vitrimers based on the transamination of vinylogous urethanes are prepared from readily accessible chemicals. These high Tg, cross‐linked materials exhibit excellent mechanical properties, while the exchangeable bonds enable full stress‐relaxation on short time scales and recycling over many cycles.
      PubDate: 2015-03-13T05:48:40.95722-05:0
      DOI: 10.1002/adfm.201404553
  • Masthead: (Adv. Funct. Mater. 11/2015)
    • Pages: n/a - n/a
      PubDate: 2015-03-12T10:23:43.430937-05:
      DOI: 10.1002/adfm.201570077
  • Flexible Janus Nanoribbons Array: A New Strategy to Achieve Excellent
           Electrically Conductive Anisotropy, Magnetism, and Photoluminescence
    • Authors: Qianli Ma; Jinxian Wang, Xiangting Dong, Wensheng Yu, Guixia Liu
      Pages: n/a - n/a
      Abstract: A new type of flexible Janus nanoribbons array with anisotropic electrical conductivity, magnetism, and photoluminescence has been successfully fabricated by electrospinning technology using a specially designed parallel spinneret. Every single Janus nanoribbon in the array consists of a half side of Fe3O4 nanoparticles/polyaniline/polymethylmethacrylate (PMMA) conductive‐magnetic bifunctionality and the other half side of Tb(BA)3phen/PMMA insulative‐photoluminescent characteristics, and all the Janus nanoribbons are aligned to form array. Owing to the unique nanostructure, the conductance along with the length direction of nanoribbons reaches up to eight orders of magnitude higher than that along with perpendicular direction, which is by far the most excellent conductive anisotropy for anisotropic conductive materials. The Janus nanoribbons array is also simultaneously endowed with magnetic and photoluminescent characteristics. The obtained Janus nanoribbons array will have important applications in the future subminiature electronic equipments owing to its high electrical anisotropy and multifunctionality. Furthermore, the design concept and fabrication technique for the flexible Janus nanoribbons array provide a new and facile approach for the preparation of anisotropic conductive films with multifunctionality. Novel Janus nanoribbons arrays with excellent electrically conductive anisotropy, magnetism, and photoluminescence have been prepared via electrospinning technology. Based on the unique nanostructure, conductance in the direction parallel to the Janus nanoribbons is almost eight orders of magnitude higher than that in the perpendicular direction, which is by far the most excellent conductive anisotropy for anisotropic conductive materials.
      PubDate: 2015-03-12T09:44:30.545353-05:
      DOI: 10.1002/adfm.201500348
  • Flexible and Highly Sensitive Strain Sensors Fabricated by Pencil Drawn
           for Wearable Monitor
    • Authors: Xinqin Liao; Qingliang Liao, Xiaoqin Yan, Qijie Liang, Haonan Si, Minghua Li, Hualin Wu, Shiyao Cao, Yue Zhang
      Pages: n/a - n/a
      Abstract: Functional electrical devices have promising potentials in structural health monitoring system, human‐friendly wearable interactive system, smart robotics, and even future multifunctional intelligent room. Here, a low‐cost fabrication strategy to efficiently construct highly sensitive graphite‐based strain sensors by pencil‐trace drawn on flexible printing papers is reported. The strain sensors can be operated at only two batteries voltage of 3 V, and can be applied to variously monitoring microstructural changes and human motions with fast response/relaxation times of 110 ms, a high gauge factor (GF) of 536.6, and high stability >10 000 bending–unbending cycles. Through investigation of service behaviors of the sensors, it is found that the microcracks occur on the surface of the pencil‐trace and have a major influence on the functions of the strain sensors. These performances of the strain sensor attain and even surpass the properties of recent strain sensing devices with subtle design of materials and device architectures. The pen‐on‐paper (PoP) approach may further develop portable, environmentally friendly, and economical lab‐on‐paper applications and offer a valuable method to fabricate other multifunctional devices. Easy‐to‐fabricate, cost‐effective, soft, lightweight, versatile sensors revolutionize the sensing technology and can be applied in personal electronic devices, artificial intelligence systems, and structural health monitoring. The pen‐on‐paper approach endows the pencil trace based on a printing paper with strain‐sensing capability for monitoring the rapid microstrain structural variation, book folding, and human motion. The sensors are low carbon footprint, disposable, and green products.
      PubDate: 2015-03-11T11:08:49.884974-05:
      DOI: 10.1002/adfm.201500094
  • Single Molecule with Dual Function on Nanogold: Biofunctionalized
           Construct for In Vivo Photoacoustic Imaging and SERS Biosensing
    • Authors: U. S. Dinish; Zhegang Song, Chris Jun Hui Ho, Ghayathri Balasundaram, Amalina Binte Ebrahim Attia, Xianmao Lu, Ben Zhong Tang, Bin Liu, Malini Olivo
      Pages: n/a - n/a
      Abstract: Multimodal imaging provides complimentary information that is advantageous in studying both cellular and molecular mechanisms in vivo, which has tremendous potential in pre‐clinical research and clinical translational imaging. It is desirable to design probes for multimodal imaging that can be administered minimally but provides multifaceted information. Herein, we demonstrate the complementary dual functional ability of a nanoconstruct for molecular imaging in both photoacoustic (PA) and surface‐enhanced Raman scattering (SERS) biosensing simultaneously in tandem. To realize this, a group of NIR active organic molecules are designed and synthesized that possess both SERS and PA activity. Nanoconstructs realized by anchoring such molecules onto gold nanoparticles are demonstrated for targeting cancer biomarkers in vivo while providing complimentary information about biodistribution and targeting efficiency. In future, such nanoconstructs could play a major role in identifying surgical margins and also for disease monitoring in translational medicine. A group of NIR active organic molecules are designed and synthesized that possess both surface‐enhanced Raman scattering (SERS) and photoacoustic (PA) activity simultaneously. The complementary dual functional ability of the nanoconstruct realized by anchoring such molecules onto gold nanoparticles is used for the targeted detection and imaging of cancer biomarker and also for biodistribution study using PA imaging and SERS biosensing in tandem.
      PubDate: 2015-03-11T11:08:39.173873-05:
      DOI: 10.1002/adfm.201404341
  • A Decaheme Cytochrome as a Molecular Electron Conduit in
           Dye‐Sensitized Photoanodes
    • Authors: Ee Taek Hwang; Khizar Sheikh, Katherine L. Orchard, Daisuke Hojo, Valentin Radu, Chong‐Yong Lee, Emma Ainsworth, Colin Lockwood, Manuela A. Gross, Tadafumi Adschiri, Erwin Reisner, Julea N. Butt, Lars J. C. Jeuken
      Pages: n/a - n/a
      Abstract: In nature, charge recombination in light‐harvesting reaction centers is minimized by efficient charge separation. Here, it is aimed to mimic this by coupling dye‐sensitized TiO2 nanocrystals to a decaheme protein, MtrC from Shewanella oneidensis MR‐1, where the 10 hemes of MtrC form a ≈7‐nm‐long molecular wire between the TiO2 and the underlying electrode. The system is assembled by forming a densely packed MtrC film on an ultra‐flat gold electrode, followed by the adsorption of approximately 7 nm TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP). The step‐by‐step construction of the MtrC/TiO2 system is monitored with (photo)electrochemistry, quartz‐crystal microbalance with dissipation (QCM‐D), and atomic force microscopy (AFM). Photocurrents are dependent on the redox state of the MtrC, confirming that electrons are transferred from the TiO2 nanocrystals to the surface via the MtrC conduit. In other words, in these TiO2/MtrC hybrid photodiodes, MtrC traps the conduction‐band electrons from TiO2 before transferring them to the electrode, creating a photobioelectrochemical system in which a redox protein is used to mimic the efficient charge separation found in biological photosystems. A molecular electron conduit of the decaheme cytochrome, MtrC, interfacing dye‐sensitized TiO2 nanocrystals to an electrode support is assembled and demonstrated. The constructed layers of MtrC and TiO2 nanocrystals photosensitized with RuP are used in a biomimetic hybrid photobiochemical system with the aim to mimic the efficient spatial charge separation found in biological photosystems.
      PubDate: 2015-03-11T11:08:18.357482-05:
      DOI: 10.1002/adfm.201404541
  • Regulation of the Stem Cell–Host Immune System Interplay Using
           Hydrogel Coencapsulation System with an Anti‐Inflammatory Drug
    • Authors: Alireza Moshaverinia; Chider Chen, Xingtian Xu, Sahar Ansari, Homayoun H. Zadeh, Scott R. Schricker, Michael L. Paine, Janet Moradian‐Oldak, Ali Khademhosseini, Malcolm L. Snead, Songtao Shi
      Pages: n/a - n/a
      Abstract: The host immune system is known to influence mesenchymal stem cell (MSC)‐mediated bone tissue regeneration. However, the therapeutic capacity of hydrogel biomaterial to modulate the interplay between MSCs and T‐lymphocytes is unknown. Here it is shown that encapsulating hydrogel affects this interplay when used to encapsulate MSCs for implantation by hindering the penetration of pro‐inflammatory cells and/or cytokines, leading to improved viability of the encapsulated MSCs. This combats the effects of the host pro‐inflammatory T‐lymphocyte‐induced nuclear factor kappaB pathway, which can reduce MSC viability through the CASPASE‐3 and CASPASE‐8 associated proapoptotic cascade, resulting in the apoptosis of MSCs. To corroborate rescue of engrafted MSCs from the insult of the host immune system, the incorporation of the anti‐inflammatory drug indomethacin into the encapsulating alginate hydrogel further regulates the local microenvironment and prevents pro‐inflammatory cytokine‐induced apoptosis. These findings suggest that the encapsulating hydrogel can regulate the MSC‐host immune cell interplay and direct the fate of the implanted MSCs, leading to enhanced tissue regeneration. The encapsulating hydrogel biomaterials, especially in the early stages of implantation, can regulate the mesenchymal stem cell–host immune system interplay and modulate the fate of the encapsulated stem cells. A new strategy is reported for enhanced bone regeneration in mesenchymal stem cell‐mediated therapies based on an RGD‐coupled alginate hydrogel coencapsulation system containing an anti‐inflammatory drug.
      PubDate: 2015-03-05T04:41:50.529078-05:
      DOI: 10.1002/adfm.201500055
  • Elastomeric Electronic Skin for Prosthetic Tactile Sensation
    • Authors: Aaron P. Gerratt; Hadrien O. Michaud, Stéphanie P. Lacour
      Pages: n/a - n/a
      Abstract: This report demonstrates a wearable elastomer‐based electronic skin including resistive sensors for monitoring finger articulation and capacitive tactile pressure sensors that register distributed pressure along the entire length of the finger. Pressure sensitivity in the order of 0.001 to 0.01 kPa−1 for pressures from 5 to 405 kPa, which includes much of the range of human physiological sensing, is achieved by implementing soft, compressible silicone foam as the dielectric and stretchable thin‐metal films. Integrating these sensors in a textile glove allows the decoupling of the strain and pressure cross‐sensitivity of the tactile sensors, enabling precise grasp analysis. The sensorized glove is implemented in a human‐in‐the‐loop system for controlling the grasp of objects, a critical step toward hand prosthesis with integrated sensing capabilities. A multimodal electronic skin including resistive sensors for monitoring finger articulation and capacitive tactile pressure sensors is reported. Pressure sensitivity across much of the range of human physiological sensing is achieved by implementing soft, compressible silicone foam and stretchable thin metal films. A sensorized glove is implemented in a human‐in‐the‐loop system for controlling the grasp of objects.
      PubDate: 2015-03-04T12:29:02.588665-05:
      DOI: 10.1002/adfm.201404365
  • Functionalized Polyelectrolytes Assembling on Nano‐BioFETs for
           Biosensing Applications
    • Authors: Xuexin Duan; Luye Mu, Sonya D. Sawtelle, Nitin K. Rajan, Ziyu Han, Yanyan Wang, Hemi Qu, Mark A. Reed
      Pages: n/a - n/a
      Abstract: A new surface functionalization scheme for nano‐Bio field effect transistors (FETs) using biocompatible polyelectrolyte thin films (PET) is developed. PET assemblies on Si nanowires (Si‐NWs) are driven by electrostatic interactions between the positively charged polymer backbone and negatively charged Si/SiO2 surface. Such assemblies can be directly coated from PET aqueous solutions and result in a uniform nanoscale thin film, which is more stable compared to the conventional amine silanization. Short oligo‐ethylene glycol chains are grafted on the PETs to prevent nonspecific protein binding. Moreover, the reactive groups of the polymer chains can be further functionalized to other chemical groups in specific stoichiometry for biomolecules detection. Therefore, it opens a new strategy to precisely control the functional group densities on various biosensor surfaces at the molecular level. In addition, such assemblies of the polymers together with the bound analytes can be removed with the pH stimulation resulting in regeneration of a bare sensor surface without compromising the integrity and performance of the Si‐NWs. Thus, it is believed that the developed PET coating and sensing systems on Si‐NW FETs represent a versatile, promising approach for regenerative biosensors which can be applied to other biosensors and will benefit real device applications, enhancing sensor lifetime, reliability, and repeatability. Functionalized polyelectrolytes are successfully synthesized and assembled on silicon nanowire field effect transistors with the aim of creating regenerative nano‐electronic biosensors. Such coating has the advantage of direct solution coating and can be applied on a wafer scale. It minimizes protein nonspecific adsorption and precisely controls the surface functional group densities at molecular level.
      PubDate: 2015-03-04T12:28:53.909269-05:
      DOI: 10.1002/adfm.201500002
  • Fast and Large Lithium Storage in 3D Porous VN Nanowires–Graphene
           Composite as a Superior Anode Toward High‐Performance Hybrid
    • Authors: Rutao Wang; Junwei Lang, Peng Zhang, Zongyuan Lin, Xingbin Yan
      Pages: n/a - n/a
      Abstract: Li‐ion hybrid capacitors (LIHCs), consisting of an energy‐type redox anode and a power‐type double‐layer cathode, are attracting significant attention due to the good combination with the advantages of conventional Li‐ion batteries and supercapacitors. However, most anodes are battery‐like materials with the sluggish kinetics of Li‐ion storage, which seriously restrict the energy storage of LIHCs at the high charge/discharge rates. Herein, vanadium nitride (VN) nanowire is demonstated to have obvious pseudocapacitive characteristic of Li‐ion storage and can get further gains in energy storage through a 3D porous architecture with the assistance of conductive reduced graphene oxide (RGO). The as‐prepared 3D VN–RGO composite exhibits the large Li‐ion storage capacity and fast charge/discharge rate within a wide working widow from 0.01–3 V (vs Li/Li+), which could potentially boost the operating potential and the energy and power densities of LIHCs. By employing such 3D VN–RGO composite and porous carbon nanorods with a high surface area of 3343 m2 g−1 as the anode and cathode, respectively, a novel LIHCs is fabricated with an ultrahigh energy density of 162 Wh kg−1 at 200 W kg−1, which also remains 64 Wh kg−1 even at a high power density of 10 kW kg−1. A 3D porous VN nanowires–graphene composite is proved to be a pseudo­capacitive material with the fast and large Li‐ion storage characteristics. Such superior composite anode coupling with a capacitance‐type porous carbon cathode is able to assemble a novel hybrid Li‐ion capacitor with an ultrahigh energy density of 162 Wh kg−1 and good rate performance.
      PubDate: 2015-03-02T14:21:49.457585-05:
      DOI: 10.1002/adfm.201404472
  • High Lithium Storage Performance of FeS Nanodots in Porous Graphitic
           Carbon Nanowires
    • Authors: Changbao Zhu; Yuren Wen, Peter A. van Aken, Joachim Maier, Yan Yu
      Pages: n/a - n/a
      Abstract: Much attention has been paid to increase the energy density of Li‐ion batteries, in order to fulfill the requirements of electric vehicles and grid‐scale energy storage. While for anodes various options are available, this is not at all the case for cathodes. In this context, the inexpensive and environmentally benign iron sulfides have been investigated as cathode materials due to the remarkably high capacity based on the conversion reaction. Here, the preparation of FeS nanodots accommodated in porous graphitic carbon nanowires is reported via a combination of electrospinning technique and biomolecular‐assisted hydrothermal method. These materials exhibit excellent electrochemical performances also as cathode materials, with energy densities even higher than the current LiCoO2 intercalation cathode. Moreover, key problems of conversion reaction, such as the low degree of reversibility, large polarization are far‐reachingly mitigated. FeS nanodots accommodated in porous graphitic carbon nanowires are obtained via the combination of electrospinning technique and a biomolecular‐assisted hydrothermal method. These materials exhibit excellent electrochemical performances as cathode materials. Key problems of conversion reaction, such as the low degree of reversibility and large polarization, are far‐reachingly mitigated.
      PubDate: 2015-03-02T06:27:44.565709-05:
      DOI: 10.1002/adfm.201404468
  • 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
    • 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
    • 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
    • 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
  • 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
    • 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
    • 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
    • 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
    • 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
  • 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
    • 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
  • 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
  • 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
  • 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
    • 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
  • 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
  • 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
  • Mesoporous Colloidal Superparticles of Platinum‐Group Nanocrystals
           with Surfactant‐Free Surfaces and Enhanced Heterogeneous Catalysis
    • Authors: Yongxing Hu; Yuzi Liu, Yugang Sun
      Pages: n/a - n/a
      Abstract: Synthesis of colloidal superparticles (CSPs) of nanocrystals, a class of assembled nanocrystals in the form of colloidal particles, has been emerging as a new frontier in the field of nanotechnology because of their potential novel properties originated from coupling of individual nanocrystals in CSPs. Here, a facile approach is reported for the controlled synthesis of mesoporous CSPs made of various platinum‐group nanocrystals that exhibit high colloidal stability and ligand‐free surfaces to significantly benefit their applications in solution‐phase heterogeneous catalysis. The synthesis relies on self‐limiting growth of composite particles through coprecipitation of both Pt‐group nanocrystals (or their precursor compounds) and silver halides on sacrificial substrates of colloidal silver particles. The intermediate silver halides in the composite particles play the critical role in limiting the continuous growth (and/or coalescence) of individual Pt‐group nanocrystals and they can be selectively dissolved to create nanoscale pores in the resulting CSPs. Colloidal superparticles consisting of platinum nanocrystals embedded in silver chloride matrix are synthesized through a self‐limited coprecipitation on sacrificial substrates of colloidal silver particles. ­Selective dissolution of silver chloride leads to the formation of porous superparticles of platinum with ligand‐free surfaces that are beneficial for solution‐phase heterogeneous catalysis.
      PubDate: 2015-01-23T11:33:17.91051-05:0
      DOI: 10.1002/adfm.201403664
  • Ultrafast All‐Polymer Electrically Tunable Silicone Lenses
    • Authors: Luc Maffli; Samuel Rosset, Michele Ghilardi, Federico Carpi, Herbert Shea
      Pages: n/a - n/a
      Abstract: Dielectric elastomer actuators (DEA) are smart lightweight flexible materials integrating actuation, sensing, and structural functions. The field of DEAs has been progressing rapidly, with actuation strains of over 300% reported, and many application concepts demonstrated. However many DEAs are slow, exhibit large viscoelastic drift, and have short lifetimes, due principally to the use of acrylic elastomer membranes and carbon grease electrodes applied by hand. Here a DEA‐driven tunable lens, the world's fastest capable of holding a stable focal length, is presented. By using low‐loss silicone elastomers rather than acrylics, a settling time shorter than 175 μs is obtained for a 20% change in focal length. The silicone‐based lenses show a bandwidth 3 orders of magnitude higher compared to lenses of the same geometry fabricated from the acrylic elastomer. Stretchable electrodes, a carbon black and silicone composite, are precisely patterned by pad‐printing and subsequently cross‐linked, enabling strong adhesion to the elastomer and excellent resistance to abrasion. The lenses operate for over 400 million cycles without degradation, and show no change after more than two years of storage. This lens demonstrates the unmatched combination of strain, speed, and stability that DEAs can achieve, paving the way for complex fast soft machines. Soft and electrically tunable lenses based on dielectric elastomer actuators are fabricated and exhibit settling time below 175 μs. Soft and compliant systems can also display fast response speed by a proper choice of materials and an adequate design. The lens, based on a low‐loss commercial silicone, is able to modulate its focal length by 20%.
      PubDate: 2015-01-23T11:31:48.285286-05:
      DOI: 10.1002/adfm.201403942
  • Magnetic Helical Microswimmers Functionalized with Lipoplexes for Targeted
           Gene Delivery
    • Authors: Famin Qiu; Satoshi Fujita, Rami Mhanna, Li Zhang, Benjamin R. Simona, Bradley J. Nelson
      Pages: n/a - n/a
      Abstract: Artificial micro‐/nanoswimmers have various potential applications including minimally invasive diagnosis and targeted therapies, environmental sensing and monitoring, cell manipulation and analysis, and lab‐on‐a‐chip devices. Inspired by natural motile bacteria such as E. Coli, artificial bacterial flagella (ABFs) are one kind of magnetic helical microswimmers. ABFs can perform 3D navigation in a controllable fashion with micrometer precision under low‐strength rotating magnetic fields (
      PubDate: 2015-01-22T13:39:44.734553-05:
      DOI: 10.1002/adfm.201403891
  • Biodegradable Thin Metal Foils and Spin‐On Glass Materials for
           Transient Electronics
    • Authors: Seung‐Kyun Kang; Suk‐Won Hwang, Sooyoun Yu, Jung‐Hun Seo, Elise A. Corbin, Jiho Shin, Dae Seung Wie, Rashid Bashir, Zhenqiang Ma, John A. Rogers
      Pages: n/a - n/a
      Abstract: Biodegradable substrates and encapsulating materials play critical roles in the development of an emerging class of semiconductor technology, generally referred as “transient electronics”, whose key characteristic is an ability to dissolve completely, in a controlled manner, upon immersion in ground water or biofluids. The results presented here introduce the use of thin foils of Mo, Fe, W, or Zn as biodegradable substrates and silicate spin‐on‐glass (SOG) materials as insulating and encapsulating layers, with demonstrations of transient active (diode and transistor) and passive (capacitor and inductor) electronic components. Complete measurements of electrical characteristics demonstrate that the device performance can reach levels comparable to those possible with conventional, nontransient materials. Dissolution kinetics of the foils and cytotoxicity tests of the SOG yield information relevant to use in transient electronics for temporary biomedical implants, resorbable environmental monitors, and reduced waste consumer electronics. Materials, fabrication strategies, dissolution kinetics, and biocompatibility studies of transient electronics systems built on thin metal foils passivated by layers of spin‐on glass (SOG) are presented. Transient electronic components exhibit comparable performances to conventional, nontransient substrates. Dissolution kinetics of the materials cured at different temperatures reveal key aspects of their corrosion chemistry, and in vitro cell cultures demonstrate their biocompatibility.
      PubDate: 2015-01-12T06:44:01.307523-05:
      DOI: 10.1002/adfm.201403469
  • Superparticles: Mesoporous Colloidal Superparticles of
           Platinum‐Group Nanocrystals with Surfactant‐Free Surfaces and
           Enhanced Heterogeneous Catalysis (Adv. Funct. Mater. 11/2015)
    • Authors: Yongxing Hu; Yuzi Liu, Yugang Sun
      Pages: 1613 - 1613
      Abstract: Mesoporous Pt colloidal nanoparticles are prepared through co‐precipitation of both Pt and AgCl nanocrystals on sacrificial substrates of colloidal Ag particles. As reported by Y. Sun, Y. Hu, and Y. Liu on page 1638, this strategy can be extended to other platinum group metals and the mesoporous colloidal nanoparticles exhibit high colloidal stability and ligand‐free surfaces to benefit solution‐phase heterogeneous catalysis.
      PubDate: 2015-03-12T10:23:41.168664-05:
      DOI: 10.1002/adfm.201570074
  • Tunable Optics: Ultrafast All‐Polymer Electrically Tunable Silicone
           Lenses (Adv. Funct. Mater. 11/2015)
    • Authors: Luc Maffli; Samuel Rosset, Michele Ghilardi, Federico Carpi, Herbert Shea
      Pages: 1614 - 1614
      Abstract: On page 1656, S. Rosset, H. Shea, and colleagues present a soft, flexible, and deformable biomimetic lens based on dielectric elastomer actuators (a.k.a. artificial muscles) that is capable of electrically modulating its focal length by 20% in less than 200 microseconds.
      PubDate: 2015-03-12T10:23:41.217309-05:
      DOI: 10.1002/adfm.201570075
  • Contents: (Adv. Funct. Mater. 11/2015)
    • Pages: 1615 - 1620
      PubDate: 2015-03-12T10:23:39.487704-05:
      DOI: 10.1002/adfm.201570076
  • Unraveling the Sinuous Grain Boundaries in Graphene
    • Authors: Zhuhua Zhang; Yang Yang, Fangbo Xu, Luqing Wang, Boris I. Yakobson
      Pages: 1621 - 1621
      PubDate: 2015-03-12T10:23:41.522622-05:
      DOI: 10.1002/adfm.201500272
  • Photolithography: Two‐Photon Nanolithography Enhances the
           Performance of an Ionic Liquid–Polymer Composite Sensor (Adv. Funct.
           Mater. 11/2015)
    • Authors: Natalia A. Bakhtina; Ute Loeffelmann, Neil MacKinnon, Jan G. Korvink
      Pages: 1682 - 1682
      Abstract: A novel ionic liquid–polymer composite material is reported by J. G. Korvink and co‐workers on page 1683, 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: 2015-03-12T10:23:41.4618-05:00
      DOI: 10.1002/adfm.201570078
  • Energy Storage: Dual Support System Ensuring Porous Co–Al Hydroxide
           Nanosheets with Ultrahigh Rate Performance and High Energy Density for
           Supercapacitors (Adv. Funct. Mater. 11/2015)
    • Authors: Xiaoliang Wu; Lili Jiang, Conglai Long, Tong Wei, Zhuangjun Fan
      Pages: 1763 - 1763
      Abstract: Porous Co‐Al LDH with dodecyl sulfate anion and graphene sheets as structural and conductive supports, is developed by Z. J. Fan and co‐workers on page 1648. Owing to fast ion/electron transport paths, porous and integrated structure, the as‐obtained electrode exhibits high specific capacitance, ultra‐high rate capability, and high energy density at a very high power density.
      PubDate: 2015-03-12T10:23:38.671432-05:
      DOI: 10.1002/adfm.201570079
  • Gene Therapy: Magnetic Helical Microswimmers Functionalized with
           Lipoplexes for Targeted Gene Delivery (Adv. Funct. Mater. 11/2015)
    • Authors: Famin Qiu; Satoshi Fujita, Rami Mhanna, Li Zhang, Benjamin R. Simona, Bradley J. Nelson
      Pages: 1764 - 1764
      Abstract: Magnetic helical microswimmers, called artificial bacterial flagella (ABFs), can perform precise 3D navigation in liquids under low‐strength rotating magnetic fields (
      PubDate: 2015-03-12T10:23:43.5311-05:00
      DOI: 10.1002/adfm.201570080
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