维生素B6在纳米金/石墨烯修饰电极上的电化学行为

将金纳米粒子电沉积在石墨烯修饰的玻碳电极表面,研究了维生素B6(VB6)在该修饰电极上的电化学行为。扫描电镜用于该修饰电极组装过程的形貌表征。实验结果表明:VB6在此修饰电极上出现一个良好的氧化峰,在最佳实验条件下,其氧化峰电流与VB6浓度在5.0×10-8～2.0×10-5 mol/L范围内呈线性关系,其线性回归方程为I(μA)=0.5697c(μmol/L)+0.06275,R=0.9992,检出限为2.0×10-8 mol/L(S/N=3)。一些常见的干扰物质如抗坏血酸不干扰VB6的检测。方法已用于片剂中VB6的含量的检测。     

A multi-wall carbon nanotubes-dicetyl phosphate electrode for the determination of hypoxanthine in fish.

An enzymeless sensor based on a multi-walled carbon nanotubes-dicetyl phosphate (MWCNT-DCP) film modified vitreous carbon electrode was developed for the determination of hypoxanthine. The MWCNT-DCP film modified electrode showed a remarkable enhancement effect on the oxidation peak current of hypoxanthine. Under the optimized conditions, the oxidation peak current is proportional to the concentration of hypoxanthine over the range from 5.0 x 10(-7) to 2.0 x 10(-4) mol L(-1) with a detection limit (S/N = 3) of 2.0 x 10(-7) mol L(-1). The MWCNT-DCP film modified electrode has been successfully used to detect hypoxanthine in fish samples.     

Electrochemical determination of methimazole based on the acetylene black/chitosan film electrode and its application to rat serum samples

A novel method has been developed for the determination of methimazole, which was based on the enhanced electrochemical response of methimazole at the acetylene black/chitosan composite film modified glassy carbon electrode. The electrochemical behavior of methimazole was studied at this film electrode by cyclic voltammetry and differential pulse voltammetry. The experimental results showed that methimazole exhibited a remarkable oxidation peak at 0.63V at the film electrode. Compared with the bare glassy carbon electrode, the oxidation peak current increased greatly, and the peak potential shifted negatively, which indicated that the acetylene black/chitosan film electrode had good catalysis to the electrochemical oxidation of methimazole. The enhanced oxidation current of methimazole was indebted to the nano-porus structure of the composite film and the enlarged effective electrode area. The influences of some experimental conditions on the oxidation of methimazole were tested and the calibration plot was examined. The results indicated that the differential pulse response of methimazole was linear with its concentration in the range of 1.0×10(-7) to 2.0×10(-5)mol/L with a linear coefficient of 0.998, and in the range of 4.0×10(-5) to 3.0×10(-4)mol/L with a linear coefficient of 0.993. The detection limit was 2.0×10(-8)mol/L (S/N=3). The film electrode was used to detect the content of methimazole in rat serum samples by the standard addition method with satisfactory results.     

一步电沉积纳米铜/石墨烯/壳聚糖复合膜修饰玻碳电极测定邻苯二酚

用一步电沉积法制备了纳米铜/石墨烯/壳聚糖复合膜修饰玻碳电极。用循环伏安法(CV)和差分脉冲伏安法(DPV)对邻苯二酚在该修饰电极的电化学行为进行了研究。实验结果表明,在pH值为7.0的磷酸盐缓冲液(PBS)中,该修饰电极对邻苯二酚具有良好的电催化作用,其电化学信号与邻苯二酚的浓度在1.0×10-6～2.0×10-4mol/L范围内呈良好的线性关系,线性相关系数为0.991。检出限为1×10-7mol/L。结果表明,纳米铜/石墨烯/壳聚糖复合膜修饰电极显著提高了邻苯二酚的电化学响应信号,并表现出良好的选择性和重现性。该方法成功用于水样中邻苯二酚含量的测定。     

辣根过氧化酶在磁性纳米修饰的离子注入电极上的电化学和电催化行为

辣根过氧化酶(HRP)在Co/NH2/ITO离子注入电极上有一对良好的氧化还原峰,峰电位分别为Epc=-0.2 V,Epa=-0.01 V(vsAg/AgCl)。该修饰电极对H2O2具有催化作用,可以用作H2O2的生物传感器,峰电流与H2O2的浓度分别在1.0×10-10~2.0×10-8mol/L和2.0×10-8~1.0×10-7mol/L范围内呈线性关系,线性回归方程分别为Ip(mA)=2.2986+0.06632c(nmol/L)和Ip(mA)=3.5788+7.3053E-4c(nmol/L),相关系数分别为0.9972和0.9688。检出限为1.0×10-10mol/L。     

Amperometric determination of glutathione and cysteine on a Pd-IrO(2) modified electrode with high performance liquid chromatography in rat brain microdialysate

A Pd/IrO(2) co-electrodeposited glassy carbon electrode was prepared and the electrochemical behavior of glutathione (GSH) at this chemically modified electrode (CME) has been studied by cyclic voltammetry (CV). The results indicated that the modified electrode efficiently exhibited electrocatalytic oxidation for GSH with relatively high sensitivity, stability, and long-life. Coupled with high-performance liquid chromatography (HPLC), the Pd/IrO(2) modified electrode was utilized for the electrochemical detection (ECD) of the thiocompounds, glutathione and cysteine (Cys). The peak currents were linear with the substance concentrations in the range of 1.0 x 10(-5) mol L(-1) to 8.0 x 10(-4) mol L(-1) for GSH and 4.0 x 10(-6) mol L(-1) to 2.0 x 10(-4) mol L(-1) for Cys. The detection limits were 2.0 x 10(-6) mol L(-1) for GSH and 5.0 x 10(-7) mol L(-1) for Cys with S/N of 3. The method has been successfully applied to assess the contents of GSH and Cys in rat brain microdialysates.     

基于石墨烯基复合物和聚天青Ⅰ的HRP传感器检测有机过氧化物的研究

利用电化学还原氧化石墨烯(GO)的方法将石墨烯(rGO)固定在电极表面上,然后电沉积氢氧化铜和氢氧化镍复合物,构成石墨烯/金属氢氧化物复合纳米材料修饰的玻碳电极(GCE),并通过电聚合天青Ⅰ将辣根过氧化酶(HRP)固定在GCE/rGO/Cu(OH)_2-Ni(OH)_2表面,制得GCE/rGO/Cu(OH)_2-Ni(OH)_2/HRP-PA。对石墨烯/金属氢氧化物复合纳米材料进行了SEM和能谱表征。通过电化学阻抗法和循环伏安法对传感器的制备过程和电化学性能进行了研究,并进一步分别对过氧化氢叔丁基(BHP)及过氧化氢异丙苯(CHP)进行了分析测定。该传感器对BHP和CHP具有良好的检测效果,在2.0×10~(-5)~9.2×10~(-4)mol/L范围内响应电流与BHP浓度呈良好的线性关系,检出限为9.9×10~(-6)mol/L;在3.0×10~(-6)~1.0×10~(-4)mol/L范围内响应电流与CHP浓度呈良好的线性关系,检出限为6.9×10~(-7)mol/L。     

氧化铜-过氧化聚吡咯-还原氧化石墨烯复合膜修饰电极非酶检测葡萄糖

先以氧化石墨烯(Graphen oxide,GO)为阴离子掺杂剂,采用电化学聚合法制备了聚吡咯-氧化石墨烯复合膜(PPy-GO)。分别在0.10 mol/L Na Cl和0.10 mol/L NaOH溶液中对其进行还原和过氧化处理,制得过氧化聚吡咯-还原氧化石墨烯复合膜(OPPy-ERGO)。再以此OPPy-ERGO复合膜为载体,采用电化学沉积法制备了氧化铜-过氧化聚吡咯-还原氧化石墨烯复合膜修饰电极(CuO-OPPy-ERGO/CCE)。通过扫描电镜和电化学方法对此电极进行表征,研究了葡萄糖在此修饰电极上的电化学行为。结果表明,此电极对葡萄糖的电氧化过程表现出高的催化活性和良好的抗干扰能力。在0.20 mol/L NaOH溶液中,安培法检测葡萄糖的线性范围为5.0×10~(-7)~1.0×10~(-3)mol/L,检出限(3Sb)为2.0×10~(-7)mol/L,灵敏度为121.8μA/(mmol·L~(-1))。该电极用于血清中葡萄糖含量的测定,加标回收率为96.0%~110.1%。     

还原氧化石墨烯-多壁碳纳米管复合膜负载金纳米粒子修饰玻碳电极检测双酚A

以水合肼为还原剂,采用均相还原法制备还原氧化石墨烯-多壁碳纳米管复合材料(rGO-MWCNTs),通过滴涂法将其修饰到玻碳电极(GCE)表面.以此复合材料为载体,采用电化学方法制备了金纳米粒子-还原氧化石墨烯-多壁碳纳米管复合膜修饰电极(AuNPs-rGO-MWCNTs/GCE).通过扫描电镜(SEM)、EDS能谱技术和电化学方法对此电极进行了表征.研究了双酚A在修饰电极上的电化学行为.结果表明,此电极对双酚A的电极过程具有良好的电化学活性,在0.10 mol/L PBS溶液(pH 7.0)中,微分脉冲伏安法测定双酚A的线性范围为5.0 × 10-9~1.0 × 10-7 mol/L和1.0 × 10-7~2.0 × 10-5 mol/L,检出限为1.0 ×10-9 mol/L(S/N=3). 将此电极用于模拟水样和超市购物小票样品中双酚A含量的测定,加标回收率分别为97%~110%和98%~104%.     

A multiwall carbon nanotubes film-modified carbon fiber ultramicroelectrode for the determination of nitric oxide radical in liver mitochondria

A novel chemically modified electrode based on the multiwall carbon nanotubes (MWNTs) film-coated carbon fiber ultramicroelectrode (CFUE) has been described for the determination of nitric oxide radical (.NO). The electrochemical behaviors of MWNTs-modified CFUE have been characterized in 0.2 mmol L(-1) K(4)Fe(CN)(6) and 0.1 mol L(-1) KCl solution. The Nafion film was used to avoid some electroactive interferences. The amount of Nafion was optimized, and some possible interferents [such as nitrite (NO(2)(-)), nitrate (NO(3)(-)), ascorbate, dopamine (DA), l-arginine (l-Arg), etc.] were tested and evaluated. The oxidation peak current of .NO increases significantly at the MWNT/Nafion-modified CFUE, in contrast to that at the bare and the Nafion-modified CFUE, and the oxidation peak potential is at 0.78 V (vs. SCE), which can be used for the detection of .NO. The oxidation peak current is linearly with the concentration of .NO from 2x10(-7) to 8.6x10(-5) mol L(-1), and the detection limit is 2x10(-8) mol L(-1). The liver mitochondria in Carassius auratus were isolated and .NO release from mitochondria was monitored by using this ultramicroelectrode system.     

Study of carbon nanotubes-HRP modified electrode and its application for novel on-line biosensors

In this paper, multi-walled carbon nanotubes (MWCNTs) were successfully immobilized on the surface of a glassy carbon electrode by mixing with horse-radish peroxidase (HRP). The electrochemical behavior of H2O2 was also studied with the MWCNTs-HRP modified electrode as a working electrode. The MWCNTs-HRP modified electrode showed excellent response of reduction current for the determination of H2O2 at the potential of -300 mV (vs. Ag/AgCl). We assembled the MWCNTs-HRP modified electrode in a thin-layer flow cell and the H2O2 solution was continuously introduced into the cell with a syringe pump. We optimized the sensitivity of the H2O2 sensor by adjusting the working potential and the pH of the buffer solution. The peak current increased linearly with the concentration of H2O2 in the range 3.0 x 10(-7) to approximately 2.0 x 10(-4) mol L(-1). The detection limit is 1.0 x 10(-7) mol L(-1) (S/N = 3). The interferences from ascorbic acid, uric acid and other electroactive substances can be greatly excluded since the sensor can be operated at -300 mV. Stability and reproducibility of the MWCNTs-HRP chemically modified electrode were also studied in this paper. Fabricated with glucose and lactate oxidase, the MWCNTs-HRP electrode was also applied to prepare the on-line glucose and lactate biosensors because of the high sensitivity for the determination of H2O2.     

基于SiO2纳米粒子固定辣根过氧化物酶的生物传感器

制备了尺寸均一的SiO2纳米粒子(60nm),并将其用于固定辣根过氧化物酶.以儿茶酚为电子媒介体制得的H2O2传感器的检测范围为1.7×10-7～1.9×10-5mol/L,检出限为8.3×10-8mol/L.达到95%稳态电流所用时间少于10s.该传感器的米氏常数为7.8μmol/L,表明所固定的酶具有较高的生物活性.     

Electrocatalytic oxidation of nitric oxide at nano-TiO2/Nafion composite film modified glassy carbon electrode

A novel nanocrystalline TiO₂ (nano-TiO₂) and Nafion composite film modified glassy carbon electrode has been developed for the determination of nitric oxide (NO) radical in an aqueous solution. This modified electrode can be employed as a NO sensor with a low detection limit, fast response, high sensitivity and selectivity. Two apparent anodic peaks were observed at 0.67 and 0.95 V at the nano-TiO₂ modified glassy carbon electrode by differential pulse voltammetry (DPV). After further modification with a thin film of Nafion, which was capable of preventing some anionic interference such as nitrite and ascorbic acid, only one peak appeared and the peak current enhanced greatly. The chronocoulometric experimental results showed NO was oxidized by one-electron transfer reaction at the composite film modified electrode. The amperometric responses increased linearly with the concentrations of NO ranging from 3.6×10⁻⁷ mol/L to 5.4×10⁻⁵ mol/L. The detection limit was estimated to be 5.4×10⁻⁸ mol/L. In this sensor system, the modification film provides complete selectivity for NO over nitrite anions (NO₂⁻).     

Nitric oxide biosensors based on Hb/phosphatidylcholine films.

Hemoglobin (Hb) was entrapped in a phosphatidylcholine (PC) film and immobilized at a pyrolytic graphite (PG) electrode surface. Its electron-transfer reactivity and enzyme activity were characterized by employing electrochemical methods. It was observed that Hb exhibited direct electrochemistry as well as enzyme-like activity towards the electrocatalytic reduction of NO in PC film. An unmediated, reagentless nitrogen oxide (NO) biosensor was accordingly prepared. Experimental results revealed that the peak current related to NO was linearly proportional to its concentration in the range of 1.0 x 10(-7)-3.0 x 10(-4) mol/L. The detection limit was estimated to be 1.0 x 10(-7) mol/L. Considering its good stability, nice selectivity and easy construction, this biosensor shows great promise for the rapid determination of traces of NO.     

Incorporation of horseradish peroxidase in a Kieselguhr membrane and the application to a mediator-free hydrogen peroxide sensor.

Horseradish peroxidase was incorporated in a kieselguhr membrane. The electron-transfer process of the enzyme was examined by cyclic voltammetry. It was observed that the electron-transfer reactivity of horseradish peroxidase was greatly enhanced, and that direct electrochemistry was accordingly feasible. Using the merits of the direct electron-transfer reactivity of horseradish peroxidase and its specific enzymatic catalysis towards hydrogen peroxide, an unmediated hydrogen peroxide biosensor was constructed. The calibration plot of this hydrogen peroxide sensor was linear in the range of 2.0 x 10(-6) mol/L - 6.5 x 10(-4) mol/L. The relative standard deviation was 4.1% for 6 successive determinations at a concentration of 1.0 x 10(-4) mol/L. The detection limit was 1.0 x 10(-6) mol/L.     

钯/聚苯胺纳米多层膜的制备及对抗坏血酸和多巴胺的催化氧化

采用脉冲电位法(PPSM)结合聚苯胺(PANI)的层层自组装制备了Pd/PANI交替沉积纳米多层膜, 并用于抗坏血酸(AA)和多巴胺(DA)的检测. 实验发现, 多层膜结构形貌及催化性能受前躯体K₂PdCl₆浓度、 脉冲条件及膜厚度等影响. 当K₂PdCl₆浓度为2×10^-3 mol/L, 阴极脉冲电位为-0.3 V, 阶跃次数为17时, 5层Pd/PANI修饰玻碳电极对AA和DA的催化性能最佳; 在0.1 mol/L磷酸盐缓冲液中, AA和DA的氧化峰明显分离[ΔE_p(AA, DA)=160 mV], 其峰电流与浓度分别在5×10^-5～4×10^-4和4×10^-5～1×10^-4 mol/L范围内呈较好线性关系, 实现了对AA和DA的同时测定. 该修饰电极具有良好的抗干扰性和稳定性.     

基于二氧化锆和碳纳米管协同作用的过氧化氢生物传感器

过氧化氢作为一种重要的化工产品在纺织行业、化工行业、造纸工业、环保行业、电子行业、食品卫生行业及其他领域得到广泛的应用~([1]).     

聚色氨酸／镍复合膜修饰电极测定抗坏血酸的研究

采用电化学聚合法制备了聚色氨酸／镍复合膜修饰玻碳电极,研究了抗坏血酸在该修饰电极上的电化学行为,建立了测定痕量抗坏血酸的新方法。在pH6．2的磷酸盐缓冲溶液中,抗坏血酸在修饰电极上产生一个灵敏的氧化峰,采用线性扫描伏安法测定,其氧化峰电流与抗坏血酸浓度在2．0×10^-6 -1．0×10^-3mol／L范围内呈良好的线性关系,检出限为5．0×10^-7mol／L。对1．0×10^-4mol／L抗坏血酸溶液平行测定6次,测定结果的相对标准偏差为1．9％。该法用于片剂中抗坏血酸含量的测定,加标回收率为97．8％～101．2％。     

普鲁士蓝/壳聚糖杂化膜修饰氧化锌球腔阵列/氧化铟锡电极制备及应用

用Langmuir-Blodgett技术制成了附着聚苯乙烯小球的氧化铟锡(InSnO)模板。将此模板水平置于由硝酸锌及柠檬酸组成的前驱体溶胶中,用溶胶-凝胶法制得氧化锌球腔阵列/氧化铟锡电极。采用电沉积法得到普鲁士蓝/壳聚糖杂化膜修饰的氧化锌球腔阵列/氧化铟锡电极。该电极在pH 7.0～8.0的溶液中具有良好的电化学活性,过氧化氢浓度在7.67×10-7～4.72×10-4mol.L-1范围内与相应的电流响应值呈线性关系,检出限(3S/N)为2.4×10-7mol.L-1。测定2.0×10-5mol.L-1过氧化氢溶液时,其相对标准偏差(n=10)为3.8%。     

基于表面活性剂单分子层修饰碳糊电极的一氧化氮电化学传感器及其应用

报道了一种表面活性剂单分子层修饰碳糊电极,并用于NO的高灵敏电化学检测。研究表明,表面活性剂通过烷基链在电极表面形成的疏水性单分子层微环境对NO的电化学响应具有较好的促进作用。其中,阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)对NO的电化学氧化表现出最强的催化活性和增敏作用。在Nafion膜覆盖的CTAB修饰碳糊电极上,NO的安培响应与其浓度在3.6×10-8～1.8×10-5mol/L范围内呈良好的线性关系,检出限为1.8×10-8mol/L。该电极作为低成本、高灵敏的NO电化学传感器,被成功应用于大鼠肺组织细胞中NO释放的实时监测。