Nano/micro-scaled materials based optical biosensing of glucose

Diabetes is a chronic metabolic disease that lasts a person's life and the estimation of blood glucose concentration is one of the main diagnostic criteria for this disease. The past decade has witnessed a huge demand for new biocompatibility and high-performance glucose biosensors. Non-enzymatic optical glucose sensing using nano/microscaled materials has surged significantly as it provides a direct visualized and cost-effective way to measure glucose concentrations. This review, in a non-exhaustive way, considers some of the recent most important achievements in the glucose-sensitive optical biosensors based upon nano/microscaled materials. Such materials are capable of mimicking the activities of the enzymes which oxidize glucose to release H₂O₂. The overall framework of the review can be divided into three parts. The first part describes the colorimetric glucose sensing using nano/microscaled materials as enzyme mimics for the oxidation of different chromogenic substrates. In the second part, some recent developments in chromogenic substrate-free fluorescence glucose sensing facilitated by nano/microscaled materials are elaborated. The third part reviews the glucose-sensing through Förster resonance energy transfer (FRET) based assays. Finally, some current challenges, gaps in fundamental understanding and future improvements in the field of optical glucose biosensors are discussed.     

纳米银的制备及其在SERS上的研究

纳米银制备的方法繁多,综述了用液相法、固相法制备纳米银,给出了这些方法得到的纳米银的表面增强拉曼散射（SERS）结果,并提出了分子吸附状态的一些影响因素。对生物技术、理论分析（如密度泛函理论）应用于纳米银的制备以及表面增强拉曼散射（SERS）的研究等提出了展望。     

Effect of atomic layer deposition temperature on the performance of top-down ZnO nanowire transistors

This paper studies the effect of atomic layer deposition (ALD) temperature on the performance of top-down ZnO nanowire transistors. Electrical characteristics are presented for 10-μm ZnO nanowire field-effect transistors (FETs) and for deposition temperatures in the range 120°C to 210°C. Well-behaved transistor output characteristics are obtained for all deposition temperatures. It is shown that the maximum field-effect mobility occurs for an ALD temperature of 190°C. This maximum field-effect mobility corresponds with a maximum Hall effect bulk mobility and with a ZnO film that is stoichiometric. The optimized transistors have a field-effect mobility of 10 cm²/V.s, which is approximately ten times higher than can typically be achieved in thin-film amorphous silicon transistors. Furthermore, simulations indicate that the drain current and field-effect mobility extraction are limited by the contact resistance. When the effects of contact resistance are de-embedded, a field-effect mobility of 129 cm²/V.s is obtained. This excellent result demonstrates the promise of top-down ZnO nanowire technology for a wide variety of applications such as high-performance thin-film electronics, flexible electronics, and biosensing.     

SMA-纳米SiC及SMA-纳米金刚石复合膜制备及其Cu2+离子吸附性能

以纳米SiC及纳米金刚石粉体为添加剂,通过苯乙烯与顺丁烯二酸酐的聚合,成功制备了苯乙烯-马来酸酐-纳米碳化硅(SMA-纳米SiC)及苯乙烯-马来酸酐-纳米金刚石(SMA-nano diamond)复合薄膜材料。通过热重分析(TG)、傅里叶红外光谱仪(FTIR)和扫描电子显微镜(SEM)对吸附复合膜的结构进行表征。研究了SMA-纳米SiC及SMA-纳米金刚石复合膜的吸水性及其对二价铜(Cu²⁺)离子的吸附特性。结果表明,无机纳米颗粒的添加均提高了复合薄膜的耐热特性,提高了热分解温度。当纳米粉体含量在0.8~1.2 g之间,可以获得较为均匀的泡沫状多孔复合薄膜。浸泡6 h,纳米SiC添加量为1.0 g的复合膜吸水率低至4.81%。纳米金刚石添加量为1.0 g,复合膜吸水率低至3.52%。适量的纳米SiC及纳米金刚石可以提高复合膜的耐水性能。SMA-纳米SiC及SMA-纳米金刚石复合膜材料均对Cu²⁺离子具有一定的吸附特性,泡沫状复合膜吸附性能最佳。纳米SiC及纳米金刚石能够有效改善SMA膜对重金属离子的吸附性能。     

Hydrolysis of Alkyl Ester on Lipase/Silicalite-1 Catalyst

Pure silica zeolites have been prepared in powder and pellets form with different surface chemical properties in order to investigate how the binding forces in the lipase enzyme adsorption influence the final conformation of the immobilized enzyme and its catalytic activity. The catalytic activity of the adsorbed lipase have been tested in the alkyl esters hydrolysis reaction. The higher alkyl-esters conversion is observed for the lipase immobilized on the supports prepared in OH⁻ media compared to the fluoride media supports. The obtained results can be explained by the two different non-covalent interactions between the external surface of zeolites and the enzyme.     

Review on carbon-derived,solid-state,micro and nano sensors for electrochemical sensing applications

The aim of this review is to summarize the most relevant contributions in the development of electrochemical sensors based on carbon materials in the recent years. There have been increasing numbers of reports on the first application of carbon derived materials for the preparation of an electrochemical sensor. These include carbon nanotubes, diamond like carbon films and diamond film-based sensors demonstrating that the particular structure of these carbon material and their unique properties make them a very attractive material for the design of electrochemical biosensors and gas sensors.Carbon nanotubes (CNT) have become one of the most extensively studied nanostructures because of their unique properties. CNT can enhance the electrochemical reactivity of important biomolecules and can promote the electron-transfer reactions of proteins (including those where the redox center is embedded deep within the glycoprotein shell). In addition to enhanced electrochemical reactivity, CNT-modified electrodes have been shown useful to be coated with biomolecules (e.g., nucleic acids) and to alleviate surface fouling effects (such as those involved in the NADH oxidation process). The remarkable sensitivity of CNT conductivity with the surface adsorbates permits the use of CNT as highly sensitive nanoscale sensors. These properties make CNT extremely attractive for a wide range of electrochemical sensors ranging from amperometric enzyme electrodes to DNA hybridization biosensors. Recently, a CNT sensor based fast diagnosis method using non-treated blood assay has been developed for specific detection of hepatitis B virus (HBV) (human liver diseases, such as chronic hepatitis, cirrhosis, and hepatocellular carcinoma caused by hepatitis B virus). The linear detection limits for HBV plasma is in the range 0.5–3.0 µL^? 1 and for anti-HBVs 0.035–0.242 mg/mL in a 0.1 M NH₄H₂PO₄ electrolyte solution. These detection limits enables early detection of HBV infection in suspected serum samples. Therefore, non-treated blood serum can be directly applied for real-time sensitive detection in medical diagnosis as well as in direct in vivo monitoring.Synthetic diamond has been recognized as an extremely attractive material for both (bio-) chemical sensing and as an interface to biological systems. Synthetic diamond have outstanding electrochemical properties, superior chemical inertness and biocompatibility. Recent advances in the synthesis of highly conducting nanocrystalline-diamond thin films and nano wires have lead to an entirely new class of electrochemical biosensors and bio-inorganic interfaces. In addition, it also combines with development of new chemical approaches to covalently attach biomolecules on the diamond surface also contributed to the advancement of diamond-based biosensors. The feasibility of a capacitive field-effect EDIS (electrolyte-diamond-insulator-semiconductor) platform for multi-parameter sensing is demonstrated with an O-terminated nanocrystalline-diamond (NCD) film as transducer material for the detection of pH and penicillin concentration. This has also been extended for the label-free electrical monitoring of adsorption and binding of charged macromolecules. One more recent study demonstrated a novel bio-sensing platform, which is introduced by combination of a) geometrically controlled DNA bonding using vertically aligned diamond nano-wires and b) the superior electrochemical sensing properties of diamond as transducer material. Diamond nano-wires can be a new approach towards next generation electrochemical gene sensor platforms.This review highlights the advantages of these carbon materials to promote different electron transfer reactions specially those related to biomolecules. Different strategies have been applied for constructing carbon material-based electrochemical sensors, their analytical performance and future prospects are discussed.     

Effect of desiccant characteristics on the properties of PS/zeolite functional packaging materials

Desiccant composites were prepared from a polystyrene homopolymer (PS) and a high impact copolymer (HIPS). Five zeolites were used as adsorbents, which included the A and X types frequently used in industrial practice. Composites containing zeolites up to 50 vol% were homogenized in an internal mixer and then compression molded to 1 mm thick plates. The results proved that the water adsorption capacity of zeolites depends on the total volume of the pores, whereas the rate of adsorption on thermodynamics, on the equilibrium constant of adsorption. On the other hand, zeolite characteristics influence the moisture adsorption of the composites only marginally; adsorption capacity is determined by zeolite content, whereas the rate of adsorption is determined by the properties of the polymer. Composites prepared with X type zeolites have somewhat smaller water adsorption capacity than those containing their A type counterparts. The dispersion of the zeolite is good both in PS and in HIPS composites. Mechanical properties are excellent mainly because of the good interfacial adhesion between the components. Because of their larger surface energy, composites containing X type zeolites have larger viscosity and they reinforce the polymer more than A type desiccants. Matrix characteristics influence mainly application related properties; reinforcement and ductility is better in HIPS than in PS composites. POLYM. COMPOS., 35:2112–2120, 2014. © 2014 Society of Plastics Engineers     

3D modeling of dual-gate FinFET

The tendency to have better control of the flow of electrons in a channel of field-effect transistors (FETs) did lead to the design of two gates in junction field-effect transistors, field plates in a variety of metal semiconductor field-effect transistors and high electron mobility transistors, and finally a gate wrapping around three sides of a narrow fin-shaped channel in a FinFET. With the enhanced control, performance trends of all FETs are still challenged by carrier mobility dependence on the strengths of the electrical field along the channel. However, in cases when the ratio of FinFET volume to its surface dramatically decreases, one should carefully consider the surface boundary conditions of the device. Moreover, the inherent non-planar nature of a FinFET demands 3D modeling for accurate analysis of the device performance. Using the Silvaco modeling tool with quantization effects, we modeled a physical FinFET described in the work of Hisamoto et al. (IEEE Tran. Elec. Devices 47:12, 2000) in 3D. We compared it with a 2D model of the same device. We demonstrated that 3D modeling produces more accurate results. As 3D modeling results came close to experimental measurements, we made the next step of the study by designing a dual-gate FinFET biased at V_g1 >V_g2. It is shown that the dual-gate FinFET carries higher transconductance than the single-gate device.     

Light-emitting transistor structures based on semiconducting polymers and inorganic nanoparticles

One of the new directions in organic electronics is the development of light-emitting organic field-effect transistors, which combine the light-emitting properties of organic light-emitting diodes and the switching properties of organic field-effect transistors. Optical and electronic properties of novel nanocomposite materials based on semiconducting polymers and inorganic nanoparticles and designed for applications in organic electronics devices were investigated. Light-emitting organic field-effect transistors with composite active layers based on the soluble semiconducting polymers PFO and MEH-PPV and ZnO nanoparticles and having asymmetric electrodes (Al and Au) that inject electrons into ZnO and holes into PFO and MEH-PPV were prepared and investigated. The data are interpreted in the context of the possibility of organic field-effect transistors based on PFO: ZnO and MEH-PPV: ZnO composite films to work in both the unipolar regime and the ambipolar regime. It is shown that the mobility of charge carriers in light-emitting organic field-effect transistors based on PFO: ZnO at 300 K reaches ～0.02 for electrons and ～0.03 cm²/(V s) for holes, increasing with an increase in the concentration of nanoparticles up to ～2 cm²/(V s), a value that is comparable to the maximum mobility values for conducting polymers. Light-emitting organic field-effect transistors based on PFO: ZnO and MEH-PPV: ZnO emit light in the green and orange ranges of the optical spectrum, respectively, their electroluminescence intensities rising with an increase in either the negative bias or the positive bias at the source-drain and the gate as well as with an increase in the concentration of ZnO nanoparticles. The results indicate that light-emitting organic field-effect transistors based on soluble conjugated polymers and semiconducting ZnO nanoparticles are examples of multifunctional devices whose production technology is compatible with the modern ink-jet printing technology of organic electronics.     

聚丙烯/纳米CaCO3结构复合材料的断裂损伤分析

通过对纳米级CaCO3粒子进行表面预处理和熔融共混工艺制备了PP／纳米CaCO3复合材料，并采用了仪器化冲击试验机对冲击过程进行了分析。结果表明，经过适当表面处理的纳米CaCO3粒子可以通过熔融共混法均匀分散在聚丙烯中，粒子与基体界面结合良好；冲击试验证明，纳米CaCO3粒子对聚丙烯有明显的增韧增强效果，而材料的增韧是由于基材抵抗外力变形能力的提高和基材的屈服形变所致。     

气相低浓度甲苯在超稳Y分子筛的吸附-脱附性能

为提高Y分子筛对可挥发性有机废气的选择性吸附能力,采用高温水热处理技术对NaY分子筛进行骨架脱铝制备超稳Y分子筛(USY),并在固定床反应器中考察了USY在水汽存在下动态吸附低浓度甲苯的性能。结果表明,随着USY分子筛骨架Si/Al比的增加,虽然其微孔孔体积和比表面积发生了下降,但形成了较多的中孔结构。并且骨架硅含量增加后,USY对非极性的甲苯分子选择性吸附能力明显增加,当Si/Al为22左右,在相对湿度50%下,单位面积甲苯吸附量要比水吸附量大5.6倍。热重脱附研究表明,经过改性后,甲苯脱附温度可从NaY的300℃下降到超稳Y分子筛的160℃,具有优良的热再生性能。     

聚丙烯基纳米SiO2复合材料的流变性能研究

采用普通毛细管流变仪和高压毛细管流变仪，通过测定流变性能，研究不同表面处理工艺对PP基纳米SiO2复合材料的团聚，分散和界面性能的影响。结果表明，纳米SiO2采用偶联剂处理并包覆长链分子型分散剂后，可增加界面层厚度，形成相间缓冲层，由此增大纳米颗粒与颗粒间的距离，使纳米颗粒团聚体变得松散，摩擦阻力有所下降，熔体流动性损失减少，PP基纳米SiO2复合材料的熔融流动性基本随纳米SiO2用量的增加而下降；当纳米SiO2质量分数约为3%时，该复合材料的熔体流变性能近似于纯PP，并在挤出或注射成型的剪切速率范围内加工流动性未明显下降。     

Investigation of synergistic effect of nano sized Ag/TiO2 particles on antibacterial,physical and mechanical properties of UV-curable clear coatings by experimental design

The synergistic effect of nano titanium dioxide (10 and 30 nm) and nano silver (10 nm) as antibacterial agents were investigated on UV curable clear coating. Antibacterial and physical–mechanical properties of coating were optimized using experimental design in response surface method. Twenty different samples of nano Ag and nano TiO₂ were prepared in this method. Antibacterial properties on Gram-negative bacteria (Escherichia coli) were investigated. The results revealed that using equal amounts of two sizes of nano TiO₂ promote the antibacterial activity of nano Ag. So, the coating shows strong activity against E. coli. Physical–mechanical properties such as surface hardness, abrasion resistance, scratch resistance and gloss of the coating were evaluated. The results depicted appropriate physical–mechanical properties. Also, scanning electron microscope (SEM), atomic force microscope (AFM) and Fourier transform infrared (FT-IR) spectroscopy were used to study the effect of nano particles on coating properties.     

Adsorption, desorption and thermal oxidation of 2-CEES on nanocrystalline zeolites

In this study, FTIR spectroscopy and flow reactor measurements are used to investigate the adsorption, desorption and thermal oxidation of the mustard gas simulant, 2-chloroethyl ethyl sulfide (2-CEES), on nanocrystalline zeolites. Adsorption, desorption and thermal oxidation of 2-CEES on nanocrystalline NaZSM-5 are compared to that on nanocrystalline silicalite-1, the purely siliceous form of ZSM-5. It is shown here that NaZSM-5 is more reactive toward 2-CEES compared to silicalite. Furthermore, it is shown that the total 2-CEES adsorption capacity increases as the nanocrystalline particle size decreases suggesting that adsorption occurs on the external surface as well as in the internal pores of zeolite. Both zeolites effectively adsorb 2-CEES, suggesting that 2-CEES adsorption and subsequent thermal oxidation may be a viable method for the decontamination of mustard gas.     

纳米CaCO_3/PVC共混体系的研究

研究了纳米级CaCO3 粒子的微观形态 ,以及纳米CaCO3/PVC共混体系的流变性能和力学性能。结果表明 ,纳米CaCO3 加入量为 9质量份时 ,纳米CaCO3/PVC共混体系的缺口冲击强度可达到 31 4kJ/m2 。纳米Ca CO3 对PVC共混体系具有显著的增韧效果     

Low-voltage SnO₂ nanowire transistors gated by solution-processed chitosan-based proton conductors

Recently, a bioprotonic field-effect transistor with chitosan nanowire channel was demonstrated [Nat. Commun., 2011, 2, 476]. Here, it is interesting to find that solution-processed chitosan films with a large electric-double-layer (EDL) specific capacitance can also be used as the gate dielectrics for low-voltage individual SnO(2) nanowire transistors. The field-effect electron mobility, current on/off ratio and sub-threshold slope of such a hybrid SnO(2) nanowire device is estimated to be 128 cm(2) V(-1) s(-1), 2.3 × 10(4) and 90 mV per decade, respectively. Such low-voltage nanowire EDL transistors gated by chitosan-based proton conductors are promising for nanosensors and bioelectronics.     

Preparation of new hydrophilic poly-vinylpyridine beads and their application to immobilization of urease

Macroporous hydrophilic poly-vinylpyridine beads were prepared by suspension copolymerization of 4- (or 2-)vinylpyridine and hydrophilic cross-linking agents, such as ethylene glycol dimethacrylate (1EG) and tetraethylene glycol dimethacrylate (4EG), and their physical properties were studied. Immobilized enzymes were obtained by adsorption of urease on vinylpyridine polymers and commercially available hydrophobic polymers. The poly-4-vinylpyridine resin crosslinked with 4EG (degree of crosslinkage, 25%) showed higher water regain, larger average pore radius, and the highest adsorption of urease. Leakage of urease from immobilized urease was scarcely observed in the buffer solution used. The hydrophilicity and hydrophobicity of support affected markedly the enzymatic reaction of the immobilized enzyme. As one of the applications of the polymer-supported urease, blood urea nitrogen in human sera was determined.     

Preparation and Characterization of Nano‐TATB Explosive

Nano‐TATB was prepared by solvent/nonsolvent recrystallization with concentrated sulfuric acid as solvent and water as nonsolvent. Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) were used to characterize the appearance and the size of the particles. The results revealed that nano‐TATB particles have the shape of spheres or ellipsoids with a size of about 60 nm. Due to their small diameter and high surface energy, the particles tended to agglomerate. By using X‐ray powder diffraction (XRD), broadening of diffraction peaks and decreasing intensity were observed, when the particle sizes decreases to the nanometer size range. The corrected average particle size of nano‐TATB was estimated using the Scherrer equation and the size ranged from 27 nm to 41 nm. Furthermore, the specific surface area and pore diameter of nano‐TATB were determined by BET method. The values were 22 m²/g and 1.7 nm respectively. Thermogravimetric (TG) and Differential Scanning Calorimetric (DSC) curves revealed that thermal decomposition of nano‐TATB occurs in the range of 356.5 °C–376.5 °C and its weight loss takes place at about 230 °C. Furthermore, a slight increase in the weight loss was observed for nano‐TATB in comparison with micro‐TATB.     

Adsorptive removal of thiophene and benzothiophene over zeolites from Mae Moh coal fly ash

Zeolites have been hydrothermally synthesized using Thai coal fly ash from Mae Moh Power Plant as silica and alumina sources. The synthesis conditions, i.e., SiO₂/Al₂O₃ ratio, amount of water, amount of base, and aging temperature, were varied to prepare different topologies of zeolitic products. The zeolites attained were sodalite (SOD), gismondine (GIS), and cancrinite (CAN). The zeolites have been applied to adsorption of thiophene and benzothiophene in n-hexane solution. It was found that GIS with higher specific surface area and average pore volume had superior performance to other synthesized materials. Adsorption capacity of our developed zeolites was compared to those of commercial zeolites, i.e. NaY, HUSY, beta, and ZSM-5 obtained via the conventional synthesis methods. The results suggested a potential of zeolites derived from Mae Moh coal fly ash for removal of refractory sulfur compounds, such as benzothiophene.     

分子筛在挥发性有机物（VOCs）吸附方面的研究进展

挥发性有机物（VOCs）的去除是目前大气环境治理的主要方向。其中最广泛用于去除VOCs的方法是吸附法,吸附材料的选择是吸附法的关键环节。从分子筛作为吸附材料的角度出发,简单介绍了目前在吸附VOCs方面效果卓越的MCM-41、ZSM-5和NaY 3种分子筛,重点综述了其制备方法及其对各种VOCs的吸附效果。结果表明,分子筛比表面积、孔道、硅铝比、平衡阳离子都会对吸附效果产生影响,可通过负载贵金属或金属氧化物、表面改性处理、复合材料、结构调整等方式优化分子筛吸附性能。未来,高吸附量、高疏水性、绿色环保和低成本可再生的新型分子筛在VOCs的吸附方面将有更广阔的前景。