Facile Fabrication of a Graphene‐based Electrochemical Biosensor for Glucose Detection

A simple and effective glucose biosensor based on immobilization of glucose oxidase (GOD) in graphene (GR)/Nafion film was constructed. The results indicated that the immobilized GOD can maintain its native structure and bioactivity, and the GR/Nafion film provides a favorable microenvironment for GOD immobilization and promotes the direct electron transfer between the electrode substrate and the redox center of GOD. The electrode reaction of the immobilized GOD shows a reversible and surface‐controlled process with the large electron transfer rate constant (k_s) of 3.42±0.08 s^?1. Based on the oxygen consumption during the oxidation process of glucose catalyzed by the immobilized GOD, the as‐prepared GOD/GR/Nafion/GCE electrode exhibits a linear range from 0.5 to 14 mmol·L^?1 with a detection limit of 0.03 mmol·L^?1. Moreover, it displays a good reproducibility and long‐term stability.     

Alcohol‐Processable Organic Amorphous Electrolytes as an Effective Electron‐Injection Layer for Organic Light‐Emitting Diodes

A new series of monoammonium‐based organic electrolytes with the tetrafluoroborate (BF₄^?) counteranion have been synthesized. Replacing the pendant ethyl groups in the fluorenyl unit with 4‐ethoxyphenyl groups dramatically improves both solubility and morphological stability. The characterization of the alcohol‐processable amorphous ionic compounds as an electron‐injection layer in organic light‐emitting diodes (OLEDs) reveals that the organic electrolyte that comprises a rigid linear‐conjugated unit provides better device performance, with respect to its counterpart containing a branched bulky moiety. The capability of these compounds to facilitate electron injection from air‐stable aluminum metal is preliminarily discussed on the basis of the investigations of the electron‐only devices and photovoltaic experiments.     

SYNTHESIS AND PROPERTIES OF COPOLYMERS CONTAINING CUCURBIT[6]URIL-BASED PSEUDOROTAXANE STRUCTURE

Novel copolymers based on acrylamide（AM）and complex pseudorotaxane monomer N’-（3-vinylbenzyl）-1,4- diaminobutane dihydrochloride with cucurbit[6]uril（CB[6]）（3VBCB）were prepared via free-radical polymerization in aqueous solution,and characterized by ¹H-NMR,FT-IR,elemental analysis and static light scattering.The compositions of the copolymers（PAM3VBCB）with pseudorotaxane units were determined by ¹H-NMR and elemental analysis.Thermal properties of the copolymers were studied by TGA,and the effects of the copolymer concentration and pH on the average hydrodynamic radius（R_h）of the copolymer molecules were studied by dynamic light scattering（DLS）.The experiment data show that CB[6]beads are localized on 1,4-diaminobutane units in side chains of the copolymers.TGA results show that thermal stability of the copolymer increases with increasing the content of pseudorotaxane unit because of the enhanced rigidity and the bulky steric hindrance of 3VBCB in side chains of PAM3VBCB.DLS data show that the average hydrodynamic radius of copolymer molecules increases with the increase in the copolymer concentration,and both the pH and electrical conductivity of PAM3VBCB solutions demonstrate an acute change with addition of NaOH because of CB[6] dethreading from the side chains of PAM3VBCB.CB[6]threading and dethreading of PAM3VBCB could be controlled by addition of BaCl₂ and Na₂SO₄     

The Vital Role of Buffer Anions in the Antioxidant Activity of CeO2 Nanoparticles

Cerium oxide (CeO₂) nanoparticles display excellent antioxidant properties by scavenging free radicals. However, some studies have indicated that they can cause an adverse response by generating reactive oxygen species (ROS). Hence, it is important to clarify the factors that affect the oxidant/antioxidant activities of CeO₂ nanoparticles. In this work, we report the effects of different buffer anions on the antioxidant activity of CeO₂ nanoparticles. Considering the main anions present in the body, Tris‐HCl, sulfate, and phosphate buffer solutions have been used to evaluate the antioxidant activity of CeO₂ nanoparticles by studying their DNA protective effect. The results show that CeO₂ nanoparticles can protect DNA from damage in Tris‐HCl and sulfate systems, but not in phosphate buffer solution (PBS) systems. The mechanism of action has been explored: cerium phosphate is formed on the surface of the nanoparticles, which interferes with the redox cycling between Ce³⁺ and Ce⁴⁺. As a result, the antioxidant activity of CeO₂ nanoparticles is greatly affected by the external environment, especially the anions. These results may provide guidance for the further practical application of CeO₂ nanoparticles.     

Alkylaminosilane‐Assisted Simultaneous Etching and Growth Route to Synthesise Metal Nanoparticles Encapsulated by Silica Nanorattles

An efficient and facile method to synthesise silica nanorattles with multiple noble metal (Au and Pd) cores by a simultaneous etching and growth route has been developed. In this strategy, a dual‐functional alkylaminosilane was adopted to form the middle layer of solid organic–inorganic hybrid solid‐silica spheres (HSSSs), which enabled the selective etching of the middle hybrid layer of the HSSSs and the in situ growth of metal nanoparticles (NPs) inside the cavity in a one‐step hydrothermal reaction. By adjusting the pH values of the reaction system, the metal NPs could be grown exclusively inside the silica nanorattles, resulting in a high atomic utilisation of the noble metals. The size and number of Au cores were tunable by manipulating the initial concentration of HAuCl₄. The prepared silica nanorattles with Au cores were successfully applied to the catalytic reduction of 4‐nitrophenol and showed high catalytic activity and cycle stability. Catalysts with multiple gold cores exhibited superior catalytic activity to those with a single gold core, probably because they possess smaller Au cores with greater surface area.     

Polyfluorene derivatives pending iridium complexes: Improved optoelectronic properties by introducing D‐A units and altering pendent mode

To study influence of the donor(D)‐acceptor(A) units and pendent mode of phosphorescent moiety on the opto‐electronic properties for its resulting copolymers, two D‐A‐based polyfluorene derivatives ( P 1 and P 2) pending the red‐emitting iridium bi(phenylisoquilonato) (picolinato) [Ir(Piq)₂(pic)] unit and a polyfluorene derivative ( P 3) only pending Ir(Piq)₂(pic) unit were synthesized and characterized, in which the donor of carbazole, the acceptor of oxadiazole are grafted into the C‐9 position of fluorene, the Ir(Piq)₂(pic) unit is pended into either the C‐9 position for P 1 and P 3 or the end for P 2 of fluorene by unconjugated linkage, respectively. Their opto‐electronic properties were significantly influenced by the D‐A units and pendent mode of the Ir(Piq)₂(pic) unit. In the polymer light‐emitting devices with a configuration of ITO/PEDOT/polymers/LiF/Al, the P 1 showed best electroluminescent properties than the P 2 and P 3. The maximum current efficiency of 0.72 cd/A and the highest luminance of 1398 cd/m 2 were obtained in the P 1‐based device, which are 1.3 and 1.5 times higher than those in the P 2‐based device, respectively. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Benzodifuran‐containing well‐defined π‐conjugated polymers for photovoltaic cells

Two well‐defined alternating π‐conjugated polymers containing a soluble electroactive benzo[1,2‐b:4,5‐b′]difuran (BDF) chromophore, poly(BDF‐(9‐phenylcarbazole)) (PBDFC), and poly(BDF‐benzothiadiazole) (PBDFBTD) were synthesized via Sonogashira copolymerizations. Their optical, electrochemical, and field‐effect charge transport properties were characterized and compared with those of the corresponding homopolymer PBDF and random copolymers of the same overall composition. All these polymers cover broad optical absorption ranges from 250 to 750 nm with narrow optical band gaps of 1.78–2.35 eV. Both PBDF and PBDFBTD show ambipolar redox properties with HOMO levels of ?5.38 and ?5.09 eV, respectively. The field‐effect mobility of holes varies from 2.9 × 10^?8 cm² V^?1 s^?1 in PBDF to 1.0 × 10^?5 cm² V^?1 s^?1 in PBDFBTD. Bulk heterojunction solar cell devices were fabricated using the polymers as the electron donor and [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester as the electron acceptor, leading to power conversion efficiencies of 0.24–0.57% under air mass 1.5 illumination (100 mW cm^?2). These results indicate that their band gaps, molecular electronic energy levels, charge mobilities, and molecular weights are readily tuned by copolymerizing the BDF core with different π‐conjugated units. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and photovoltaic properties of conjugated side chains polymers with different electron‐withdrawing and donating end groups

A series of novel low band gap polymers containing conjugated side chains with 4,7‐dithien‐5‐yl‐2,1,3‐benzodiathiazole and different electron‐withdrawing end groups of aldehyde ( PT‐DTBTCHO ), 2‐ethylhexyl cyanoacetate ( PT‐DTBTCN ), 1,3‐diethyl‐2‐thiobarbituric acid ( PT‐DTBTDT ), and electron‐donating end group of 2‐methylthiophene ( PT‐DTBTMT ) have been designed and synthesized. All polymers exhibit good solubility in common organic solvents, film‐forming ability, and thermal stability. These conjugated polymers show the broad ultraviolet‐visible absorption and the narrow optical band gaps in the range of 1.65–1.90 eV. Through changing the end group of conjugated side chains, the photophysical properties and energy levels of the polymers were tuned effectively. Bulk heterojunction solar cells based on the blend of these polymers and (6,6)‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) reached the best power conversion efficiency (PCE) of 2.72%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Heparin Interacting Protein Mediated Assembly of Nano‐Fibrous Hydrogel Scaffolds for Guided Stem Cell Differentiation

A new methodology is developed to conjugate hyaluronic acid (HA) hydrogel with novel nano‐fibrous architectures via non‐covalent assembly that specifically allows for targeted adipose‐derived stem cells (ASCs) differentiation and soft tissue engineering. The assembly of non‐covalently associated hydrogel network produced via the interaction of a low molecular weight heparin (LMWH) modified HA derivative and heparin interacting protein (HIP). The multifunctional star poly(ethylene glycol) (PEG) and HIP copolymer has the capability to mediate the non‐covalent assembly of nano‐fibrous HA hydrogel networks via affinity interactions with LMWH. The effect of the HIP mediation on in vitro gelation, rheological characteristics, degradation, equilibrium swelling, adipose‐derived stem cells (ASCs) proliferation and differentiation of nano‐fibrous hydrogel is examined. The results suggest the potential utility of this unique design of the bioactive nano‐fibrous HA hydrogel in directing the differentiation of ASCs and adipogenesis in ECM‐mimetic scaffolds in vitro. These studies demonstrate that this nano‐fibrous HA hydrogel can render the formulation of a therapeutically effective platform for in vitro adipogenesis applications.