SDS存在下肌红蛋白在乙炔黑电极上的电化学行为研究

基于十二烷基磺酸钠(SDS)存在下,研究肌红蛋白(Mb)在乙炔黑电极上的电化学行为,建立了一种简便灵敏的肌红蛋白电化学分析方法.采用循环伏安法(CV)和差分脉冲伏安法(DPV)进行分析,SDS能显著提高肌红蛋白在乙炔黑电极上的还原峰电流.在最佳实验条件下,峰电流与肌红蛋白浓度在5.6×10-10 mol/L～2.8×10-7mol/L范围内有良好的线性关系,检出限为4.5×10-10 mol/L.方法用于合成样品中肌红蛋白含量的测定.乙炔黑电极可以作为传感器,用于样品中Mb的舍量测定.     

石墨烯修饰电极分子印迹电化学传感器的研制及其对多巴胺的测定

以石墨烯为电极增敏材料,多巴胺印迹聚合物为特异性识别材料,采用滴涂法组装石墨烯修饰电极的分子印迹电化学传感器。考察了pH值、石墨烯浓度、印迹聚合物浓度对传感器的影响,优化的实验条件为:pH 7.0,石墨烯浓度为0.5g/L,印迹聚合物浓度为20g/L。实验表明,该印迹传感器对多巴胺的响应电流远大于非印迹电极,同时该印迹传感器对多巴胺具有较好的选择性,检测范围为2.0×10-7～1.0×10-4mol/L,检出限(S/N=3)为6.8×10-8mol/L。该传感器用于盐酸多巴胺注射液的测定,其回收率为98%～105%。     

基于碳纳米管-纳米二氧化锰增强的H2O2修饰电极的研制

将碳纳米管(CNT)和纳米二氧化锰(Nano-MnO2)分散在壳聚糖(CHIT)溶液中,用涂敷法固定到玻碳电极表面,制成修饰电极.由于碳纳米管具有良好的电子传递性能,使纳米二氧化锰对H2O2的电催化活性明显提高,通过循环伏安法、计时电流法对传感器的性能进行了研究.在最佳测试条件下,该传感器对H2O2的线性范围为1.5×10-6 ～5.0×10-2 mol/L,检出限为4×10-7 mol/L.用于实际样品的测定,结果满意.     

以OT为底物固体电极伏安法测定辣根过氧化物酶及其标记物的研究

以玻碳电极为工作电极研究了邻联甲苯胺(OT)为底物微分脉冲伏安法测定辣根过氧化物酶(HRP)及其标记物的方法。HRP能够催化H2O2氧化OT,其反应产物在玻碳电极上-0.58V(vs.Ag/AgCl)左右被还原产生一个灵敏的还原峰,还原峰电流随着酶浓度的增大而增大,借助此还原电流可以测定HRP,并进而可用于以HRP为标记物的酶免疫分析。对酶催化反应条件和酶催化反应产物的测定条件进行了详细的研究,在最佳实验条件下测定游离HRP的线性范围是2.0×10-9～4.0×10-8g/mL,检出限为1.6×10-9g/mL;测定游离的酶标记物(IgG HRP),稀释范围为1∶2000～1∶400000,最大稀释比为1∶400000。     

多壁碳纳米管修饰乙炔炭黑电极测定碘

以多壁碳纳米管修饰乙炔炭黑电极为工作电极,研究了碘离子在该修饰电极上的伏安分析特性,讨论了支持电解质种类、酸度等因素对碘离子氧化峰电流的影响,获得了最佳的实验条件. 在0.4 mol/L KH2PO4缓冲液(pH=4.0)中,从200 mV以200 mV/s的速率正向扫描至1 200 mV,碘离子在570 mV处出现一灵敏的氧化峰,峰电流比未修饰电极增大约3倍. 采用二阶导数线性扫描伏安法进行定量分析,峰电流与碘离子的浓度在2.0×10-6～1.0×10-3 mol/L范围内呈良好的线性关系,检出限为8.0×10-7 mol/L. 方法用于食盐中碘含量的测定,相对标准偏差为1.2%～1.6%,回收率为97.4%～103%.     

基于纳米MnO2-MWCNTs复合材料修饰的葡萄糖传感器

采用水热法制备了纳米MnO2,并用红外光谱,X射线衍射(XRD)和扫描电子显微镜(SEM)对其进行了表征。将碳纳米管和纳米MnO2分散在壳聚糖溶液中,用滴涂法固定到玻碳电极表面,制成修饰电极。利用计时电流法对该葡萄糖传感器的性能进行了研究,纳米MnO2-MWCNTs复合物对葡萄糖的氧化有明显的催化作用。在优化的条件下,葡萄糖在5.0×10-5～3.0×10-2mol/L浓度范围内,计时电流与浓度之间呈线性关系,检出限为1.5×10-5 mol/L(S/N=3)。对1.0×10-3 mol/L葡萄糖溶液平行测定8次的相对标准偏差(RSD)为2.1%。该传感器可成功用于葡萄糖注射液中葡萄糖的测定,回收率在96.4%～98.6%之间。     

磺基水杨酸修饰电极联吡啶钌电化学发光体系测定可待因的研究

基于磷酸可待因对联吡啶钌在该电极上的电化学及其发光行为的增敏作用,建立了一种直接测定磷酸可待因的电化学发光新方法。在最佳实验条件下,磷酸可待因在1.0×10-4～4.0×10-6mol/L和4.0×10-6～2.0×10-7mol/L与相对发光强度呈线性关系,检出限为1.0×10-7mol/L(S/N=3)。连续测定4.0×10-7mol/l磷酸可待因5次,发光强度的RSD为2.7%。方法用于模拟尿样中磷酸可待因的测定,结果满意。     

盐酸异丙嗪的微波增敏方波伏安法测定

以玻碳电极作工作电极,在微波作用下用循环伏安法和方波伏安法研究了盐酸异丙嗪的电化学特性,结果表明微波可以增大峰电流,并应用于盐酸异丙嗪的检测,建立了一种新的检测盐酸异丙嗪的电化学方法.在最佳实验条件下,无微波作用时用方波伏安法检测盐酸异丙嗪,其响应电流与盐酸异丙嗪的浓度在4.0×10-6 ～1.0×10-4 mol/L范围呈线性关系(r=0.998 2,n=7),线性回归方程为I(A)=0.040 3c(mol/L)+5.0×10-7,检出限为4.0×10-7 mol/L;在微波作用下用方波伏安法检测盐酸异丙嗪,其响应电流与盐酸异丙嗪的浓度在4.0×10-6 ～1.0×10-4 mol/L范围有很好的线性关系(r=0.999 1,n=7),线性回归方程为I(A)=0.045 7c(mol/L)+6.0×10-7,检出限为2.0×10-7 mol/L.在4.0×10-6 ～1.0×10-4 mol/L范围微波增敏的峰电流与无微波条件下峰电流的比值平均值为1.22.该方法用于盐酸异丙嗪片的测定,结果满意.     

基于巯基乙酸与离子液体共修饰的过氧化氢生物传感器的研究

采用静电组装技术,将离子液体[Bmim]PF6与辣根过氧化物酶(HRP)交替固定在巯基乙酸修饰的金电极表面,制备了(HRP/[Bmim]PF6)n多层组装膜,并通过电化学阻抗谱(EIS)和傅立叶红外反射光谱(ATR-FTIR)对制备的组装膜进行了表征.以对苯二酚为电子媒介体,过氧化氢在(HRP/[Bmim]PF6)2双层组装膜传感器上的线性范围为1.6×10-6 ～2.5×10-3 mol/L,检出限为5.7×10-7 mol/L(S/N=3),达到95%稳态电流用时少于5 s,Kappm值为0.048 mmol/L,表明所固定的酶具有较高的生物活性.     

L-半胱氨酸自组装电极循环伏安法测定多巴胺

建立了痕量多巴胺(DA)电化学分析方法.在pH 7.6的0.2 mol/L Na2HPO4-NaH2PO4 0.1 mol/L KCl底液中,L-半胱氨酸(L-Cys)自组装金电极对多巴胺有明显的电催化氧化作用,考察了该电极作为DA传感器的实验条件.结果表明:DA在L-Cys/Au电极上的氧化峰电流与多巴胺的浓度在一定范围内成线性关系,线性范围为6.7×10-5～4.6×10-3 mol/L,检出限为8.4×10-6 mol/L,平行测定8次,相对标准偏差为3.2%,用于盐酸多巴胺注射液中DA的测定,回收率为94%～96%.     

明胶固定辣根过氧化物酶制备H_2O_2传感器

用明胶将辣根过氧化物酶(HRP)固定于多壁碳纳米管(MWNT)和茜素红(AR)修饰的玻碳(GC)电极上,制成HRP生物传感器(HRP/AR/MWNT/GC),然后在3%戊二醛(GA)中进行交联改性,以克服明胶膜易溶胀的缺点,并提高膜的稳定性.同时详细探讨了该传感器对H2O2的响应性能,并优化了实验条件.结果表明,该传感器对H2O2的线性响应范围为5.0×10-6～1.0×10-3mol/L,线性相关系数为0.9932,检出限为1.0×10-7mol/L,且放于4℃环境30d后,峰电流值约为原来的72.1%.该传感器响应快速,灵敏度高,且具有良好的重现性、稳定性及较长的使用寿命,具有潜在的应用价值.     

Amperometric hydrogen peroxide biosensor based on the immobilization of heme proteins on gold nanoparticles-bacteria cellulose nanofibers nanocomposite

A novel matrix, gold nanoparticles-bacterial cellulose nanofibers (Au-BC) nanocomposite was developed for enzyme immobilization and biosensor fabrication due to its unique properties such as satisfying biocompatibility, good conductivity and extensive surface area, which were inherited from both gold nanoparticles (AuNPs) and bacterial cellulose nanofibers (BC). Heme proteins such as horseradish peroxidase (HRP), hemoglobin (Hb) and myoglobin (Mb) were successfully immobilized on the surface of Au-BC nanocomposite modified glassy carbon electrode (GCE). The immobilized heme proteins showed electrocatalytic activities to the reduction of H₂O₂ in the presence of the mediator hydroquinone (HQ), which might be due to the fact that heme proteins retained the near-native secondary structures in the Au-BC nanocomposite which was proved by UV-vis and IR spectra. The response of the developed biosensor to H₂O₂ was related to the amount of AuNPs in Au-BC nanocomposite, indicating that the AuNPs in BC network played an important role in the biosensor performance. Under the optimum conditions, the biosensor based on HRP exhibited a fast amperometric response (within 1 s) to H₂O₂, a good linear response over a wide range of concentration from 0.3 μM to 1.00 mM, and a low detection limit of 0.1 μM based on S/N = 3. The high performance of the biosensor made Au-BC nanocomposite superior to other materials as immobilization matrix.     

Investigation of the direct electrochemistry and electrocatalysis of myoglobin on gold nanorods modified electrode

Direct electrochemistry and electrocatalysis of myoglobin (Mb) on a gold nanorod (AuNR)‐decorated carbon ionic liquid electrode (CILE) were studied in this article. The fabricated Nafion/Mb/AuNRs/CILE was used as an electrochemical biosensor for determining trichloroacetic acid (TCA) and sodium nitrite (NaNO₂). AuNRs exhibited high metal conductivity, and acted as the bridge between electrochemical active centers of Mb and the substrate electrode with the electron transfer rate accelerated. Electrochemical performances of Nafion/Mb/AuNRs/CILE were checked in pH 3.0 phosphate buffer solution with the electrochemical parameters calculated. Low detection limits and wide linear ranges were obtained in electrocatalytic investigations of different catalytic substrates including TCA and NaNO₂, which exhibited potential applications in actual sample detection.     

A Third‐Generation Hydrogen Peroxide Biosensor Based on Horseradish Peroxidase Immobilized in Carbon Nanotubes/ SBA‐15 Film

A new third‐generation biosensor for H₂O₂ assay was developed on the basis of the immobilization of horseradish peroxidase (HRP) in a nanocomposite film of carbon nanotubes (CNTs)‐SBA‐15 modified gold electrode. The biological activity of HRP immobilizing in the composite film was characterized by UV‐vis spectra. The HRP immobilized in the nanocomposite matrix displayed excellent electrocatalytic activity to the reduction of H₂O₂. The effects of the experimental variables such as solution pH and working potential were investigated using steady‐state amperometry. Under the optimal conditions, the resulting biosensor showed a linear range from 1 µM to 7 mM and a detection limit of 0.5 µM (S/N=3). Moreover, the stability and reproducibility of this biosensor were evaluated with satisfactory results.     

Chemically glycosylation improves the stability of an amperometric horseradish peroxidase biosensor

We constructed a biosensor by electrodeposition of gold nano-particles (AuNPs) on glassy carbon (GC) and subsequent formation of a 4-mercaptobenzoic acid self-assembled monolayer (SAM). The enzyme horseradish peroxidase (HRP) was then covalently immobilized onto the SAM. Two forms of HRP were employed: non-modified and chemically glycosylated with lactose. Circular dichroism (CD) spectra showed that chemical glycosylation did neither change the tertiary structure of HRP nor the heme environment. The highest sensitivity of the biosensor to hydroquinone was obtained for the biosensor with HRP-lactose (414 nA μM⁻¹) compared to 378 nA μM⁻¹ for the one employing non-modified HRP. The chemically glycosylated form of the enzyme catalyzed the reduction of hydroquinone more rapidly than the native form of the enzyme. The sensor employing lactose-modified HRP also had a lower limit of detection (74 μM) than the HRP biosensor (83 μM). However, most importantly, chemically glycosylation improved the long-term stability of the biosensor, which retained 60% of its activity over a four-month storage period compared to only 10% for HRP. These results highlight improvements by an innovative stabilization method when compared to previously reported enzyme-based biosensors.     

Preparation of Magnetic Ordered Mesoporous Carbon Composite and Its Application in Direct Electrochemistry of Horseradish Peroxidase

A novel magnetic ordered mesoporous carbon composite was prepared. Electrochemical measurements showed that the ordered mesoporous carbon composite provided an excellent matrix for the co‐adsorption of horseradish peroxidase (HRP). HRP could be separated and collected by the application of a magnetic field and its direct electron‐transfer could be achieved in the solution, not on the electrode thereby preventing the degradation of the enzyme. The cyclic voltammetric experimental results of HRP indicated that HRP displayed a pair of stable peaks with a formal potential of ?0.306 V in PBS. The resulting biosensor exhibited fast amperometric response to hydrogen peroxide.     

金纳米棒荧光探针应用于多酚化合物检测新方法

以金纳米棒为荧光探针,在20％甲醇(pH 5.0～6.0)介质中,以植物多酚化合物芒果苷、瑞香素和白藜芦醇为检测对象,建立了3种植物多酚的灵敏、简便、快速检测新方法.多酚化合物基于其与金纳米棒表面的十六烷基三甲基溴化铵(CTAB)分子间的疏水作用而在金纳米棒表面富集,同时使金纳米棒在719 nm处的荧光强度减弱,在一定范围内多酚化合物的浓度与金纳米棒荧光强度成正比,其检出限分别为5.0×10-8、8.0×10-8、2.0×10 -7mol/L.     

A novel amperometric biosensor based on gold nanoparticles-mesoporous silica composite for biosensing glucose

We report a novel bienzyme biosensor based on the assembly of the glucose oxidase (GOD) and horseradish peroxidase (HRP) onto the gold nanoparticles encapsulated mesoporous silica SBA-15 composite (AuNPs-SBA-15). Electrochemical behavior of the bienzyme bioconjugates biosensor is studied by cyclic voltammetry and electrochemical impedance spectroscopy. The results indicate that the presence of mesoporous AuNPs-SBA-15 greatly enhanced the protein loadings, accelerated interfacial electron transfer of HRP and the electroconducting surface, resulting in the realization of direct electrochemistry of HRP. Owing to the electrocatalytic effect of AuNPs-SBA-15 composite, the biosensor exhibits a sensitive response to H₂O₂ generated from enzymatic reactions. Thus the bienzyme biosensor could be used for the detection of glucose without the addition of any mediator. The detection limit of glucose was 0.5 μM with a linear range from 1 to 48 μM. Supported by the National Natural Science Foundation of China (Grant Nos. 20635020 & 90606016)     

Potential control of horseradish peroxidase immobilization on gold electrode

Based on the self-assembled monolayer (SAM) technique, a number of methods for immobilizing protein onto electrodes have been recently reported, such as entrapment method in which the protein was wrapped with regenerated silk fibroin[1], self-assem- bled monolayer[2] and silica sol-gel[3], layer-by-layer self-assembly method in which the protein was ad-sorbed to opposite charged macromolecules due to electrostatic attraction[4], reversed micelle[5], cross- linked method[6] and surface spin-coa…     

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized on L-glutathione self-assembled monolayers

A novel hydrogen peroxide biosensor has been fabricated based on covalently linked horseradish peroxidase （HRP） onto L- glutathione self-assembled monolayers （SAMs）. The SAMs-based electrode was characterized by electrochemical methods, and direct electrochemistry of HRP can be achieved with formal potential of-0.242 V （vs. saturated Ag/AgCl） in pH 7 phosphate buffer solution （PBS）, the redox peak current is linear to scan rate and rate constant can be calculated to be 0.042 s^-1. The HRP-SAMs- based biosensors show its better electrocatalysis to hydrogen peroxide in the concentration range of 1 × 10^-6 mol/L to 1.2 × 10^-3 mol/L with a detection limit of 4 × 10^-7 mol/L. The apparent Michealis-Menten constant is 3.12 mmol/L. The biosensor can effectively eliminate the interferences of dopamine, ascorbic acid, uric acid, catechol and p-acetaminophen.