Construction of amperometric glucose biosensor based on <Emphasis Type="Italic">in-situ</Emphasis> fabricated hierarchical meso-macroporous SiO<Subscript>2</Subscript> modified Au film electrodes

Gold nanoparticles (GNPs) modified hierarchical meso-macroporous (HMMP) SiO₂ layer on the surface of Au film electrode was developed as a novel enzyme immobilization matrix for biosensors construction. HMMP SiO₂-Au bilayer film electrodes were in-situ fabricated with magnetron sputtering process and templating method. The as-prepared HMMP SiO₂ films were characterized by SEM, TEM, and cyclic voltammetry (CV). The modified layer of HMMP SiO₂ has interconnected pore channels, and the sizes of macropores and mesopores are about 330 nm and 9 nm, respectively. The HMMP SiO₂ modified gold film electrodes not only have no diffusion barrier for electrochemical probes, but also exhibit good electrochemical properties. In addition, the activity and stability of the immobilized enzyme can be commendably retained in HMMP SiO₂. The biosensor exhibits an excellent bioelectrocatalytic response to glucose with a linear range of 1.0×10^-4 M-1.0×10^-2 M, high sensitivity of 18.0 μA·mM^-1·cm^-2, as well as good reproducibility and stability.     

农药乐果的吸附溶出伏安法测定

用吸附溶出伏安法测定了农药乐果的含量。在1×10~(-7)～1×10~(-4)mol/dm~3范围内浓度与波高有良好的线性关系,最低检测限为1×10~(-8)mol/m~3方法简便、准确而灵敏。     

2,4,6-三氨基嘧啶在玻碳电极上的电化学行为

用线性扫描伏安法 (LSV)、循环伏安法 (CV)和微分脉冲伏安法 (DPV)等电化学手段研究了 2 ,4,6 三氨基嘧啶 (TAP)的电化学行为。结果表明 :该化合物在玻碳电极表面存在吸附特性 ,在 0 .1 0mol·L- 1 的 pH 5 .0Britton Robinson (B R)缓冲溶液中于1 .2 0V(vs.Ag/AgCl)处有一灵敏的氧化峰。在选定的最佳条件下 ,其浓度在 8.0× 1 0 - 6～ 3.2×1 0 - 4 mol·L- 1 范围内与氧化峰电流有良好的线性关系 ,检测限为 6.5× 1 0 - 6mol·L- 1 。     

Gap-plasmon of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@Ag core-shell nanostructures for highly enhanced fluorescence detection of Rhodamine B

A novel gap-plasmon of Fe₃O₄@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B (RB) was developed. Fe₃O₄@Ag core-shell nanostructures with Ag shell and Fe₃O₄ core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane (MPTS). To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe₃O₄@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe₃O₄@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance (SPR) band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon (LSP) and the gap plasmon near-field coupling with the Fe₃O₄@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10^-7 mol/L, and the Fe₃O₄@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe₃O₄@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.     

石墨烯修饰电极同时测定邻苯二酚和对苯二酚

制备石墨烯玻碳修饰电极,进而采用循环伏安法、交流阻抗等电化学方法对该电极进行表征,研究该石墨烯修饰电极在邻苯二酚和对苯二酚上的电化学行为．结果表明,在石墨烯修饰电极上邻苯二酚的氧化峰电位和还原峰电位分别是270mV和161mV,对苯二酚氧化峰电位和还原峰电位分别是145mV和64mV,由于邻苯二酚和对苯二酚的氧化峰电位大约相离125mV,还原峰大约相离97mV,因此适合同时检测邻苯二酚和对苯二酚．邻苯二酚和对苯二酚的浓度在5．0×10-6～1．0×10-4mol／L范围内与峰电流分别呈良好的线性关系;且在8．0×10-5～1．0×10-3mol／L范围能同时检测邻苯二酚和对苯二酚,邻苯二酚的检测限可达5．0×10～7mol／L,对苯二酚的检测限可达1．0×10-mol／L．该石墨烯修饰电极可作为电化学传感器用于邻苯二酚和对苯二酚的含量同时测定及环境水体中实际样品的分析．     

Novel fluorescence sensor based on covalent immobilization of 3-amino-9-ethylcarbazole via electrostatically assembled gold nanoparticle layer

A novel technique of immobilizing indicator dyes by electrostatic adsorption and covalent bonding to fabricate optical sensors was developed. 3-Amino-9-ethylcarbazole (AEC) was attached to the outmost surface of quartz glass slide via aminosilanizing the slide, crosslinking chitosan, adsorbing Au nanoparticle, self-assembling HS(CH₂)₁₁OH, and coupling AEC. Thus, an AEC-immobilized optical sensor was obtained. The sensor exhibits a wide linear response range from 7.0×10⁻⁷ to 1.0×10⁻⁴ mol/L and a correlation coefficient of 0.995 9 for the detection of 2-nitrophenol. The detection limit and response time of the sensor are 1.0×10⁻⁷ mol/L and less than 10 s, respectively. The fluorescence intensity of the used sensor can be restored to the blank value by simply rinsing with blank buffer. A very effective matrix for immobilizing indicator dye is provided by the proposed technique, which is adaptable to other indicator dyes with amino groups besides AEC. Foundation item: Project(20775010) supported by the National Natural Science Foundation of China; Project(208095) supported by the Key Project of Ministry of Education, China; Project(07A006) supported by the Scientific Research Fund of Hunan Provincial Education Department, China; Project(07JJ3020) supported by Hunan Provincial Natural Science Foundation of China     

Laccase biosensor using magnetic multiwalled carbon nanotubes and chitosan/silica hybrid membrane modified magnetic carbon paste electrode

A simple and rapid strategy to construct laccase biosensor for determination of catechol was investigated. Magnetic multiwalled carbon nanotubes (MMCNT) which possess excellent capability of electron transfer were prepared by chemical coprecipitation method. Scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) were used to identify its surfacetopography and magnetization, respectively. Laccase was immobilized on the MMCNT modified magnetic carbon paste electrode by the aid of chitosan/silica (CS) hybrid membrane. Using current-time detection method, the biosensor shows a linear response related to the concentration of catechol in the range from 10⁻⁷ to 0.165×10⁻³ mol/L. The corresponding detection limit is 3.34×10⁻⁸ mol/L based on signal-to-noise ratios (S/N) ≥3 under the optimized conditions. In addition, its response current retains 90% of the original after being stored for 45 d. The results indicate that this proposed strategy can be expected to develop other enzyme-based biosensors.     

全固态奎宁选择电极的研制与应用

首次报道了以奎宁碘化物与碘化铋形成的分子缔合物为电活性物的全固态盐酸奎宁选择电极 ,电极的线性响应范围为 1 .0× 1 0 - 1～ 1 .0× 1 0 - 5 mol/L ,级差为 4 0mV/pC ,检测限为 2 .5× 1 0 - 6 mol/L。pH值在 3.0 8～ 6.1 0范围内变化时 ,引起的电势变化不超过± 1mV。该电极制作简便、操作灵活、重现性好 ,结果与药典法相符。     

自组装3-氨丙基三甲氧基硅烷-磷钼酸膜修饰电极

通过在C-O-Si键在电化学活化玻碳电极表面自组装3-氨丙基三甲氧基硅烷(3-aminopropyltrimethoxysilane, APMS),再于其表面连接Keggin型结构杂多酸阴离子PMo12O403-,制备了复合膜修饰玻碳电极,采用XPS和循环伏安法研究了复合膜的基本性质。结果表明,PMo₁₂O₄₀^3-通过库仑作用力与APMS的表面-NH₂结合 (PMo₁₂O₄₀^3--APMS),可极大提高电极的稳定性,与溶液中的PMo₁₂O₄₀^3-相比,PMo₁₂O₄₀^3--APMS修饰电极表现出具有较小峰-峰分裂的PMo₁₂O₄₀^3-的三对可逆氧化还原过程,并能在较大pH范围内保持稳定。研究了修饰电极对ClO₃^-、BrO₃^-、IO₃^-还原的催化性能,与PMo₁₂O₄₀^3-修饰玻碳电极相比,该电极对三种离子均具有良好的电催化活性,对应的检出限分别为1.5×10^-5、1.0×10^-6、5×10^-7mol／L。     

对甲基苯酚在PLYS／TiO2—CS修饰电极匕的电化学行为

在含赖氨酸的磷酸盐缓冲溶液中,用循环伏安法在制备好的纳米二氧化钛-壳聚糖玻碳电极上聚合聚赖氨酸薄膜,采用循环伏安法和示差脉冲法研究对甲基苯酚在聚赖氨酸／二氧化钛-壳聚糖修饰电极上的电化学行为．实验结果表明：聚赖氨酸／二氧化钛-壳聚糖修饰电极对对甲基苯酚的氧化具有良好的电催化作用,对甲基苯酚的浓度在6．0×10^-6～1．0×10^-4mol／L范围内与峰电流呈良好的线性关系;检测限可达5．0×10^-7mol／L．该复合修饰电极可作为电化学传感器用于对甲基苯酚的含量测定及环境水体中实际样品的分析．     

Optical waveguide and nonlinear properties of Bi<Subscript>3</Subscript>NdTi<Subscript>3</Subscript>O<Subscript>12</Subscript> thin films

Neodymium-substituted bismuth titanate (Bi₃NdTi₃O₁₂, BNT) thin films were prepared on quartz substrates by a metal-organic solution deposition process. The crystalline structure was evaluated by X-ray diffraction. Waveguide property was investigated by using prism coupling technique and optical transmittance measurement. The optical nonlinearities of the film were measured by the top-hat Z-scan techniques and a large positive nonlinear refractive index, nonlinear refractive coefficient and two-photon absorption coefficient were determined to be 3.84 × 10⁻⁷ esu, 0.7523 cm²/GW and 4.81 × 10⁴ cm/GW, respectively. These results reveal that the BNT film may be a kind of new multifunctional materials.     

以酚红为底物的伏安酶联免疫分析体系测定HRP

提出酚红 H2 O2 辣根过氧化物酶 (HRP)伏安酶联免疫分析体系。酚红具有醌式结构 ,在滴汞电极上于 - 0 62V(vs .SCE)左右产生伏安还原峰。HRP催化H2 O2 氧化酚红生成非电活性产物 ,使酚红的峰高降低。利用酚红的伏安还原峰的峰高降低 ,可以测定HRP及其标记物 ,并进而可用于酶联免疫分析。以线性扫描二阶导数伏安技术测定HRP的活性 ,其线性范围为 1 .0× 1 0 - 6 ～ 1 .0× 1 0 - 4 g·L- 1 HRP ,检测限为 7.3× 1 0 - 7g·L- 1 HRP。并将该体系应用于烟草花叶病毒的测定。     

Electrochemical Sensing of Heavy Metal Ions based on Monodisperse Single-crystal Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> Microspheres

Single-crystal Fe₃O₄ with monodisperse microspheres structure has been used for individual electrochemical detection of heavy metal ions. Morphology and structure of the as-prepared Fe₃O₄ microspheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Meanwhile the electrochemical properties of the Fe₃O₄ microspheres modified glass carbon electrodes (GCE) were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and the enhanced electrochemical response in stripping voltammetry for individual detection of Pb(II), Hg(II), Cu(II), and Cd(II) was evaluated using square wave anodic stripping voltammetry (SWASV). With high specific surface area and excellent catalytic activity toward heavy metal ions, the as-prepared monodisperse and single-crystal Fe₃O₄ microspheres show a preferable sensing sensitivity (22.2 μA/μM) and limit of detection (0.0699 μM) toward Pb(II). Furthermore, the electrochemical sensor of Fe₃O₄ microspheres exhibits excellent stability and it also offers potential practical applicability for the determination of heavy metal ions in real water samples. This study provides a potential simple and low cost iron oxide for the construction of sensitive electrochemical sensors applied to monitor and control the pollution of toxic metal ions.     

Effect of aluminum addition on microstructure and properties of SiO<Subscript>2</Subscript>-B<Subscript>2</Subscript>O<Subscript>3</Subscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-CaO vitrified bond

Influence of aluminum addition on the structures and properties of SiO₂-B₂O₃-Al₂O₃-CaO vitrified bond at low sintering temperature and high strength was discussed. FTIR and XRD analyses were used to characterize the structures of the basic vitrified bond with different contents of aluminum. The bending strength and the thermal expansion coefficients were also tested. Meanwhile, the microstructures of composite specimens at sintering temperature of 660 °C were observed by scanning electron microscope (SEM). The experimental results showed that the properties of vitrified bond with 1wt% aluminum were improved significantly, where the bending strength, Rockwell hardness, and thermal expansion coefficient of the vitrified bond reached 132 MPa, 63 HRB, and 6.73×10^-6 °C^-1, respectively.     

Ferroelectric properties of Bi<Subscript>4</Subscript>Zr<Subscript>0.5</Subscript>Ti<Subscript>2.5</Subscript>O<Subscript>12</Subscript> thin films prepared on LaNiO<Subscript>3</Subscript> bottom electrode by sol-gel method

The Bi4Zr0.5Ti2.5O12 (BZT) thin films were fabricated on the LaNiO3 bottom electrode using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction, AFM and SEM. The results show that the films have a perovskite phase and dense microstructure. The 2Pr and 2Vc of the Pt/BZT/LaNiO3 capacitor are 28.2 μC/cm2 and 14.7 V respectively at an applied voltage of 25 V. After the switching of 1×1010 cycles, the Pr value decreases to 87% of its pre-fatigue values. The dielectric constant (ε) and the dissipation factor (tanδ) of the BZT thin films are about 204 and 0.029 at 1 kHz, respectively. The films show good insulating behavior according to the test of leakage current. The clockwise C-V hysteresis curve observed shows that the Pt/BZT/LaNiO3 structure has a memory effect because of the BZT film's ferroelectric polarization.     

聚天青A/辣根过氧化物酶电极的制备及性能

以循环伏安法在玻碳电极表面电化学聚合天青 A的同时实现了辣根过氧化物酶 ( HRP)的固定化 ,制备了聚天青 A/辣根过氧化物酶 ( PAA/HRP)电极。该电极对 H2 O2有很好的生物电催化还原作用 ,可在没有电子传递体的情况下催化 H2 O2 的还原 ,催化电流与 H2 O2 浓度在 1 .0× 1 0 - 6～ 6.0× 1 0 - 3mol· L- 1的范围内呈良好的线性关系 ,相关系数 r=0 .9993( n=1 6)。该酶电极制备简单 ,重现性良好 ,用于 H2 O2 的测定 ,可使用 60次以上。     

克林沙星的吸附伏安特性及其应用

在0.2 mol.L-1KH2PO4-K2HPO4(pH6.80)底液中,克林沙星(CF)在汞电极上有一线性扫描还原峰,峰电位Ep=-1.46 V(vs.Ag/AgCl),该峰说明汞电极对克林沙星具有明显的吸附性。测得CF在汞电极上的饱和吸附量sГ=4.82×10-11mol.cm-2,每个CF分子所占电极面积为2.64 nm2,CF在汞电极上的吸附符合Langmuir吸附等温式。测得吸附系数β=1.06×106,25℃时的吸附自由能ΔGθ=-32.13 kJ.mol-1,电极反应电子数n=2,不可逆体系动力学参量αna=1.44,表面电极反应速率常量ks=0.26 s-1。建立了吸附溶出伏安法测定CF的最佳条件,方法的检出限为2.0×10-8mol.L-1。     

磺胺二甲嘧啶的示波极谱法分析

研究了磺胺二甲嘧啶（ＳＭ２）的示波极谱法。磺胺二甲嘧啶在０．０１ｍｏｌ／ＬＨＣｌ介质中于－０．９９５Ｖ附近出现一清晰的阴极还原波。在１×１０－７～１×１０－４ｍｏｌ／Ｌ范围内，浓度与波高有良好的线性关系。检测下限可达３．０×１０－９ｍｏｌ／Ｌ。测定了小儿胺散中的ＳＭ２的含量，与紫外－可见分光光度法对照，结果一致。测定了尿样中ＳＭ２的含量，结果令人满意。     

Grain growth kinetics of SnO<Subscript>2</Subscript> nanocrystals synthesized by precipitation method

Monodispersed spheroidal SnO₂ nanocrystals with the grain size of 8–30 nm were synthesized by the precipitation method using SnCl₄·5H₂O (stannic chloride hydrate) as raw materials. Differential scanning calorimetry/thermogravimetry (DSC/TG), X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize the structure of SnO₂ nanocrystals. The influences of the calcination temperature and time on the lattice constant, the lattice distortion and the grain size of SnO₂ nanocrystals were discussed based on the XRD results. The grain growth kinetics of SnO₂ nanocrystals during calcination process was simulated with a conventional grain growth model which only took into account of diffusion and with a new isothermal model proposed by our group, which took into account of both diffusion and surface reactions. Using conventional model, the grain growth rate constant of SnO₂ crystals is 1.55×10⁴ nm⁵/min with a pre-exponential factor of 5 and an activation energy of 108.62 kJ/mol. Compared with the convention model, the new isothermal model is more realistic in reflecting the grain growth behavior of SnO₂ nanocrystals during the calcination process. This indicates that the grain growth of SnO₂ nanocrystals is controlled by both diffusion and reaction factors, and the effect of surface reactivity on the grain growth of SnO₂ nanocrystals could not be ignored. A combined activation energy estimated with the new isothermal model is 53.46 kJ/mol.     

流动注射计时电流法检测甲氧氯普胺

基于多壁碳纳米管修饰印刷碳电极对甲氧氯普胺的电催化作用,建立了测定甲氧氯普胺的流动注射计时电流法与印刷碳电极相比,多壁碳纳米管修饰印刷碳电极显著降低了甲氧氯普胺的氧化峰电位,提高了氧化峰电流．测定甲氧氯普胺的线性范围为8．04×10^-5-1．0×10^-3mol／L,检出限为5．0×10^-5mol／L（S/N=3）;1．0×10^-4mol／L的甲氧氯普胺测定的RSD为3．0％（n=9）．方法已成功应用于药片中甲氧氯普胺含量的测定．