Electrochemical characteristics of a platinum electrode modified with a matrix of polyvinyl butyral and colloidal Ag containing immobilized horseradish peroxidase

A new hydrogen peroxide biosensor was constructed, which consisted of a platinum electrode modified by a matrix of polyvinyl butyral (PVB) and nanometer-sized Ag colloid containing immobilized horseradish peroxidase (HRP), and using Co(bpy)₃³⁺ as mediator in the hydrogen peroxide solution. The electrochemical characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. The modified process was characterized by electrochemical impedance spectroscopy and cyclic voltammetry. The HRP immobilized on colloidal Ag was stable and retained its biological activity. The sensor displays excellent electrocatalytic response to the reduction of H₂O₂. Analytical parameters such as pH and temperature were also studied. Linear calibration for H₂O₂ was obtained in the range of 1×10^–5 to 1×10^–2 M under optimized conditions. The sensor was highly sensitive to H₂O₂, with a detection limit of 2×10^–6 M, and the sensor achieved 95% of steady-state current within 10 s. The sensor exhibited high sensitivity, selectivity and stability.     

基于双氨基三唑硫醚为中性载体的汞离子选择性电极的研究

研制了基于双氨基三唑硫醚为中性载体的阳离子选择性电极。实验表明,该电极对Hg2 具有良好的电位响应特性,在pH 2.0硝酸盐缓冲液中,电极电位呈近能斯特响应,线性响应范围为4.0 mg/L~20 g/L,斜率为33.4 mV/dec.(25℃),检出限为1.7 mg/L。该电极响应时间短(<10 s),pH范围较宽(1.3~3.3)。将该电极用于实际水样和二元混合溶液中Hg2 的检测,其结果令人满意。     

A New Amperometric Biosensor Based on HRP/Nano-Au/L-Cysteine/Poly（o-Aminobenzoic acid）-Membrane-Modified Platinum Electrode for the Determination of Hydrogen Peroxide

The third generation amperometric biosensor for the determination of hydrogen peroxide （H2O2） has been described. For the fabrication of biosensor, o-aminobenzoic acid （oABA） was first electropolymerized on the surface of platinum （Pt） electrode as an electrostatic repulsion layer to reject interferences. Horseradish peroxidase （HRP） absorbed by nano-scaled particulate gold （nano-Au） was immobilized on the electrode modified with polymerized o-aminobenzoic acid （poABA） with L-cysteine as a linker to prepare a biosensor for the detection of H2O2. Amperometric detection of H2O2 was realized at a potential of ＋20 mV versus SCE. The resulting biosensor exhibited fast response, excellent reproducibility and sensibility, expanded linear range and low interferences. Temperature and pH dependence and stability of the sensor were investigated. The optimal sensor gave a linear response in the range of 2.99×10^-6 to 3.55×10^-3 mol·L^-1 to H2O2 with a sensibility of 0.0177 A·L^-1·mol^-1 and a detection limit （S/N = 3） of 4.3×10^-7 mol·L^-1. The biosensor demonstrated a 95% response within less than 10 s.     

Highly Selective Salicylate Membrane Electrode Based on N,N＇- （Aminoethyl）ethylenediamide Bis（2-salicylideneimine） Binuclear Copper（Ⅱ） Complex as Neutral Carrier

A new ion selective electrode for salicylate based on N,N＇-（aminoethyl）ethylenediamide bis（2-salicylideneimine） binuclear copper（Ⅱ） complex [Cu（Ⅱ）2-AEBS] as an ionophore was developed. The electrode has a linear range from 1.0 × 10^-1 to 5.0 ×10^-7 mol·L^- 1 with a near-Nemstian slope of （ - 55 ±1 ） mV/decade and a detection limit of 2.0 × 10-7 mol·L^-1 in phosphorate buffer solution of pH 5.0 at 25 ℃. It shows good selectivity for Sal^- and displays anti-Hofmeister selectivity sequence： Sal^-〉SCN^-〉 ClO4^- 〉I^-〉 NO2^- 〉Br^-〉 NO3^- 〉Cl^-〉 SO3^2- 〉 SO4^2- The proposed sensor based on binuclear copper（Ⅱ）complex has a fast response time of 5-10 s and can be used for at least 2 months without any major deviation. The response mechanism is discussed in view of the alternating current （AC） impedance technique and the UV-vis spectroscopy technique. The effect of the electrode membrane compositions and the experimental conditions were studied. The electrode has been successfully used for the determination of salicylate ion in drug pharmaceutical preparations.     

Selective fluorescence response and magnetic separation probe for 2,4,6-trinitrotoluene based on iron oxide magnetic nanoparticles

Despite the rapid development of nanomaterials and nanotechnology, it is still desirable to develop novel nanoparticle-based techniques which are cost-effective, timesaving, and environment-friendly, and with ease of operation and procedural simplicity, for assay of target analytes. In the work discussed in this paper, the dye fluorescein isothiocyanate (FITC) was conjugated to 1,6-hexanediamine (HDA)-capped iron oxide magnetic nanoparticles (FITC–HDA Fe₃O₄ MNPs), and the product was characterized. HDA ligands on the surface of Fe₃O₄ MNPs can bind 2,4,6-trinitrotoluene (TNT) to form TNT anions by acid–base pairing interaction. Formation of TNT anions, and captured TNT substantially affect the emission of FITC on the surface of the Fe₃O₄ MNPs, resulting in quenching of the fluorescence at 519 nm. A novel FITC–HDA Fe₃O₄ MNPs-based probe featuring chemosensing and magnetic separation has therefore been constructed. i.e. FITC–HDA Fe₃O₄ MNPs had a highly selective fluorescence response and enabled magnetic separation of TNT from other nitroaromatic compounds by quenching of the emission of FITC and capture of TNT in aqueous solution. Very good linearity was observed for TNT concentrations in the range 0.05–1.5 μmol?L^?1, with a detection limit of 37.2 nmol?L^?1 and RSD of 4.7 % (n?=?7). Approximately 12 % of the total amount of TNT was captured. The proposed methods are well-suited to trace detection and capture of TNT in aqueous solution.

卤素离子触发亚铁四面体笼的自旋状态转换

合理构筑了3个具有固态自旋交叉特性的亚铁四面体笼状化合物1~3。单晶X射线衍射分析证实了化合物是由6个咪唑席夫碱配体和4个亚铁离子组装形成的边导向封顶胶囊结构。金属中心占据四面体的顶点,而配体组成了四面体的边。这些笼状化合物的内部空腔被咪唑基团环绕,而外部则被取代苯环包围。一个阴离子客体被限域在笼状化合物空腔内,并与笼状化合物主体产生较强的相互作用。当在笼状化合物的乙腈溶液中加入卤素离子（Cl^-和Br^-）时,溶液的颜色和MLCT峰强度会发生明显变化,表明亚铁四面体笼状化合物的自旋状态由低自旋向髙自旋发生了转换。     

用于红外激光防护的高开关率VO2薄膜

采用反应离子束溅射和后退火处理技术在石英玻璃基底上制备了具有纳米粒子的二氧化钒(VO₂)薄膜. 该薄膜具有半导体-金属相变特性,在3 μm处的开关率达到76.6%。 热致相变实验结果给出了准确的最佳退火温度为465 ℃. 仿真、热致相变和光致相变实验都显示VO₂薄膜在红外波段具有很高的光学开关特性. 光电池防护实验结果显示VO₂薄膜将硅光电池的抗干扰能力提升了2.6倍, 证明了VO₂在激光防护中的适用性. 采用连续可调节系统研究得到VO₂在室温条件下的相变阈值功率密度为4.35 W/cm², 损伤阈值功率密度为404 W/cm²。 低相变阈值和高损伤阈值都进一步证明VO₂薄膜适用于激光防护系统。本实验制备的VO₂薄膜在光开关、光电存储器、智能窗等方面也具有广泛的应用价值.     

异种DNA对胚胎发育的影响

有平衡器之东方蝾螈的DNA和无平衡器之黑斑蛙DNA当分别注射至黑斑蛙的受精卵内时.两者都能使受注射卵发育成的有些蝌蚪在左鳃盖上具有类似平衡器的突出物.基于这些事实,可以推论蝌蚪的类似平衡器的突出物既不是由于遗传转化,也不是平衡器的诱导而是DNA对胚胎发育的非特异性效应.     

纺锤形BiVO_4微米管:低温离子熔盐合成及光催化性能

以Bi(NO_3)_3·5H_2O和NH_4VO_3为原料,以氯化胆碱和尿素组成的低温离子熔盐为反应介质,采用离子热合成法成功制备出了具有纺锤状外形的BiVO_4微米管。利用XRD,SEM,UV-Vis DRS,光催化测试等手段考察了BiVO_4颗粒的物相、形貌和光催化性能。结果表明,在离子熔盐环境下可以制备出结晶良好的BiVO_4纺锤形微米管,该BiVO_4微米管长10～15μm,直径为1.5μm左右,管壁厚约为200 nm。同时,研究了pH值对BiVO_4颗粒物相与形貌的影响,发现随着pH值的变化可分别合成出具有柱状、纺锤形微米管、柱状微米管和针柱状单斜相BiVO_4颗粒。光催化测试结果表明,这些单斜白钨矿BiVO_4颗粒在可见光范围都具有一定的光催化活性,其中纺锤状微米管对罗丹明B的降解效果最佳,可见光照射4.5h后罗丹明B的降解率可达到93%。     

Highly conducting gold nanoparticles-graphene nanohybrid films for ultrasensitive detection of carcinoembryonic antigen

A new label-free amperometric immunosensor was developed for detection of carcinoembryonic antigen (CEA) based on chitosan-ferrocene (CS-Fc) and nano-TiO₂ (CS-Fc + TiO₂) complex film and gold nanoparticles-graphene (Au-Gra) nanohybrid. CS-Fc + TiO₂ composite membrane was first modified on a bare glass carbon electrode. Then Au-Gra nanohybrid was formed on the CS-Fc + TiO₂ membrane by self-assembly strategy. Next, further immobilization of anti-CEA was constructed according to the strong interaction between Au-Gra and the amido groups of anti-CEA. Since Au-Gra nanohybrid films provided a congenial microenvironment for the immobilization of biomolecules, the surface coverage of antibody protein could be enhanced and the sensitivity of the immunosensor has been improved. The good electronic conductive characteristic might be attributed to the synergistic effect of graphene nanosheets and Au NPs. The modified process was characterized by scanning electron microscope (SEM) and cyclic voltammetry (CV). Under optimized conditions, the resulting biosensor displayed good amperometric response to CEA with linear range from 0.01 to 80 ng/mL and a detection limit of 3.4 pg/mL (signal/noise = 3). The results demonstrated that the immunosensor has advantages of high conduction, sensitivity, and long life time. This assay approach showed a great potential in clinical applications and detection of low level proteins.