基于银纳米粒子/氧化石墨烯复合薄膜制备TNP电化学传感器

利用改进的Hummers法制备了氧化石墨烯(GO),以葡萄糖为还原剂直接在GO表面沉积银纳米粒子(AgNPs)得到性能稳定的AgNPs/GO纳米复合材料;基于该纳米复合材料修饰电极构建了一种新型的2,4,6-三硝基苯酚(TNP)电化学传感器。采用原子力显微镜(AFM)、扫描电镜(SEM)、透射电镜(TEM)、紫外可见光谱(UV-Vis)和交流阻抗(EIS)等多种方法对纳米复合薄膜进行了表征;并研究了TNP在复合薄膜修饰电极上的电化学行为和动力学性质。结果表明,AgNPs/GO对TNP有较强的电催化活性,在复合薄膜修饰电极出现一灵敏的氧化峰和3个还原峰;利用氧化峰可对TNP进行定量分析。同时整个电极过程明显不可逆,电极反应受到吸附步骤控制;复合膜电极表面覆盖度为5.617×10-8mol.cm-2,在所研究电位下的速率常数为9.745×10-5cm.s-1。在pH 6.8的磷酸缓冲液中,当富集电位为-0.70 V,富集时间为60 s;TNP氧化峰电流与其浓度在5.0×10-9~1.0×10-7mol.L-1范围内成良好线性关系,相关系数为0.995 8,检出限可达1.0×10-9mol.L-1。所制备的电化学传感器稳定性和选择性较好;用于实际水样中TNP的现场快速检测,加标回收率在97.6%~103.9%之间。     

聚吡咯-肝素共聚膜修饰电极对钙离子的响应

研制了聚吡咯-肝素共聚膜修饰电极,并用电化学方法进行了表征。发现该修饰电极对钙离子呈Nernst响应,电极斜率为31.0 mV/pCa,线性范围是5.0×10^-7～5.0×10^-2 mol·L^-1,可用于儿童发样中钙的测定,结果满意,还测定了该修饰电极对其他阳离子的电位选择系数。     

氢氧化镧钠米线对多倍斯伏安响应的增敏作用及其应用

氢氧化镧钠米线修饰碳糊电极对多倍斯伏安响应有明显的增敏作用,其特征是多倍斯一对氧化还原峰的峰电流增大和峰电位差减小。这种增敏作用是由于氢氧化镧钠米线修饰电极有效面积的增大以及氢氧化镧钠米线与多倍斯间的化学作用。基于多倍斯在氢氧化镧钠米线修饰碳糊电极上灵敏的氧化峰,用线性扫描伏安法测定多倍斯,线性范围是3.0×10^-10～1.0×10^-8 mol·L^-1,检测限达5×10^-11mol·L^-1。     

钒(Ⅳ/Ⅴ)电对在碳纸电极上的反应机理研究

采用循环伏安、极化曲线和交流阻抗技术研究了在0.8 mol·L^-1 VOSO₄+3.0 mol·L^-1 H₂SO₄中,V(Ⅳ/Ⅴ)电对在碳纸电极上的反应机理及可能的速度控制步骤。研究结果表明：V(Ⅳ/Ⅴ)电对在碳纸电极上的反应属准可逆过程,且氧化过程包含有后置化学转化步骤,计算得到VO²⁺的扩散系数为4.5×10^-5 cm²·s相似文献   

Cu2+和Cu+对原代培养的小鼠成骨细胞增殖、分化和钙化的影响

利用噻唑蓝(MTT)法、碱性磷酸酶(ALP)比活性测定、油红O染色和矿化结节染色及定量分析,研究了Cu²⁺和Cu⁺对原代培养的成骨细胞增殖、分化及钙化的影响。结果显示：Cu²⁺(1×10^-9~1×10^-6 mol·L^-1)促进成骨细胞增殖,随时间延长,促进作用变弱。Cu⁺(1×10^-7~1×10^-5 mol·L^-1)抑制成骨细胞增殖,随时间延长,浓度为1×10^-6 mol·L^-1的Cu⁺为促进作用,其余浓度则没有影响。对于成骨细胞分化,Cu²⁺和Cu⁺表现出相似的影响,浓度为1×10^-9和1×10^-6 mol·L^-1时均促进成骨细胞分化,而当浓度为1×10^-7和1×10^-5 mol·L^-1时,则抑制成骨细胞分化,随作用时间延长,大多数浓度均表现为促进作用。测试浓度下的Cu²⁺和Cu⁺均对成骨细胞向脂肪细胞的横向分化表现为促进效应。对矿化功能的影响,1×10^-5 mol·L^-1的Cu²⁺和Cu⁺表现出显著的抑制效应,但随浓度降低,抑制效应变弱。1×10^-7 mol·L^-1的Cu²⁺ 促进成骨细胞矿化结节的形成。结果提示：作用浓度、作用时间及铜离子的价态都是影响Cu²⁺和Cu⁺生物效应转变(从毒性到活性,从损伤到保护,从下调到上调)的关键因素。     

肌红蛋白在磷脂-月桂酸修饰的玻碳电极上的电化学行为及其分析应用

报道了肌红蛋白(Mb)在磷脂、月桂酸修饰的玻碳电极上的电化学行为 ,在 +0.2～ -0.7V(vs.Ag/AgCl)电位范围内 ,于pH6.0的0.01mol·L-1的KH2PO4、Na2HPO4底液中 ,肌红蛋白产生不可逆的还原电流峰 ;还原峰电流与肌红蛋白浓度在2.25×10-8 ～1.40×10-6 mol·L-1 范围内呈良好线性关系 ;线性回归方程为Ip(μA)=-0.01419 +0.2382cMb(10 -7mol·L -1) ,线性回归系数r(10)为0.998 ,检出限为1.20×10 -8mol·L -1,该电极可作为检测肌红蛋白的新型的高灵敏度电化学生物传感器。     

银-磷酸钛纳米复合膜的构建及其电化学生物传感

利用ITO基底上层层组装构建的多层内嵌银纳米粒子的磷酸钛薄膜固定了血红蛋白并且用于生物传感研究。由于银纳米粒子与磷酸钛膜的协同作用,实验中可以观察到Hb的直接电子传递。研究表明所制备的Hb-Ag-TiP/PDDA/ITO电极对H₂O₂响应迅速、稳定,检测限达3.3×10^-6 mol·L^-1。     

细胞色素c在硒代胱氨酸修饰电极上的直接电化学

采用电化学和接触角实验方法研究了硒代胱氨酸自组装膜修饰金电极(SeCys SAMs/Au)和十六烷基三甲基溴化铵(CTAB)-硒代胱氨酸自组装复合膜修饰金电极(CTAB-SeCys SAMs/Au)的特性. 探讨了细胞色素c(Cyt c)在SeCys SAMs/Au电极和CTAB-SeCys SAMs/Au电极上的电化学行为. 实验证明SeCys可促进Cyt c在电极上的氧化还原反应, 加入CTAB后其与SeCys之间的协同作用可在Cyt c与电极之间形成一个开放的通道, 促进作用更加明显, 且在一定浓度范围内, 随CTAB浓度(1×10^-5-1×10^-4 mol·L^-1)的增大, Cyt c在CTAB-SeCys SAMs/Au电极上的氧化还原电流增大, 在接近临界胶束浓度处出现极大值. 在CTAB-SeCys SAMs/Au电极上Cyt c产生一对氧化还原峰, 其峰电位分别为0.305和0.235 V, 其电化学过程受扩散控制. 光谱实验证实SeCys对Cyt c电化学过程的促进作用是由于SeCys与Cyt c中赖氨酸残基的结合.     

L-半胱氨酸自组装膜修饰电极对对氨基酚电催化氧化及其分析应用

在裸金电极上制备了L 半胱氨酸自组装膜修饰电极(L Cys/AuSAMs),研究了对氨基酚(p AP)在L Cys/AuSAMs上的电化学行为,发现该膜电极对p AP的氧化具有良好的电催化作用。氧化峰电位降低了128mV,测得p AP的扩散系数D为1.27×10-6cm2·s-1,初步探讨了电催化机理。采用水平衰减全反射 傅立叶变换红外光谱(ATR FTIR)技术对L Cys/AuSAMs进行了表征;方波伏安法(SquareWaveVoltammetry,SWV)测定p AP,其氧化峰峰电流与p AP浓度在1.0×10-8～8.0×10-8mol·L-1和1.0×10-7～2.0×10-4mol·L-1范围内呈线性关系,相关系数分别为0.9978和0.9977,检出限为2.0×10-9mol·L-1。该电极用于模拟废水样的测定,结果满意。     

水滑石负载的钯纳米粒子对水合肼的电催化氧化

利用共沉淀方法制备了载体水滑石(LDH), 通过离子交换法将PdCl2₄^- 插入水滑石层间, 再用水合肼将其还原, 制备得到了水滑石负载的分散状钯纳米粒子(LDH-Pd⁰). 利用X射线衍射(XRD)、透射电镜(TEM)和X射线电子能谱(XPS)等手段对所得样品进行了表征, 结果表明钯纳米粒子能很好地分散在水滑石上. 将该纳米材料修饰的玻碳电极(GCE)用于水合肼的电催化氧化, 该修饰电极表现出很好的电化学催化活性. 用循环伏安法(CV)、计时库仑法(CC)和计时安培法(i-t)对修饰电极的催化活性、有效表面积和水合肼的催化氧化机理等进行了研究. 结果表明水合肼在-0.1 V附近有明显的氧化峰, 在1.0×10^-5-2.0×10^-4 mol·L^-1范围内, 阳极峰电流与水合肼浓度间有良好的线性关系, 其检测限为9.5×10^-7 mol·L^-1. 计算得到GCE, LDH-Pd⁰/GCE 和LDH/GCE电极活化面积分别为0.02089, 0.02762 和0.02496 cm². 推知水合肼的氧化过程有4 电子和4 质子参与, 并且其在电极上的反应是受扩散控制的不可逆过程.     

Voltammetric Determination of Dopamine in Human Serum and Urine at a Glassy Carbon Electrode Modified by Cysteic Acid Based on Electrochemical Oxidation of L ‐cysteine

Abstract

The voltammetric behavior of dopamine was studied at a glassy carbon electrode modified by cysteic acid, based on electrochemical oxidation of L ‐cysteine. The modified electrode showed strong electrocatalytic activity towards dopamine and good selectivity. In a phosphate buffer solution (pH 7.4), the anodic peak current obtain from the differential pulse voltammetry of dopamine was linearly dependent on its concentration in the range of 5×10^?9 to 4.0×10^?6mol · L^?1, with a detection limit of 2×10^?9mol · L^?1. The low‐cost modified electrode had been applied to the determination of dopamine in human serum and urine samples with satisfactory results.     

Sensitive determination of the endocrine disruptor bisphenol A at ultrathin film based on nanostructured hybrid material SiO<Subscript>2</Subscript>/GO/AgNP

In this work, we described an electrochemical sensor using a nanocomposite based on graphene oxide (GO), silver nanoparticles (AgNP), and disordered mesoporous silica (SiO₂), which was used for the determination of bisphenol A in water samples. Initially, the hybrid material SiO₂/GO was synthesized via sol-gel process, subsequently decorated with AgNP with an approximate 20 nm particle size prepared directly on the surface of the SiO₂/GO using N, N-dimethylformamide (DMF) as an agent reducer. A glassy carbon electrode was modified with SiO₂/GO/AgNP and used in developing a sensitive electrochemical sensor for the determination of bisphenol A in phosphate buffer 0.1 mol L^?1 (pH 7.0). The detection limit was 45.2 nmol L^?1 with a linear response range between 1.0 × 10^?7 and 2.6 × 10^?6 mol L^?1 and a sensitivity of 1.27 × 10^?7 A mol^?1 L. Finally, the optimized electrochemical sensor was used for the quantitation of endocrine interfering in natural waters.     

Electrocatalysis Oxidation of GMP Based on Layered Double Hydroxide Functionalized with Anionic Surfactant and Room Temperature Ionic Liquid Modified Glassy Carbon Electrode

The electrocatalysis oxidation of guanosine‐5′‐monophosphate (GMP) was investigated on Mg‐Al layered double hydroxide (LDH) functionalized with sodium dodecyl sulfate (SDS) and room temperature ionic liquid (RTIL) modified glass carbon electrode (GCE). The cyclic voltammogram of GMP on the modified electrode (RTIL/ LDH‐SDS/GCE) exhibited a well defined anodic peak at 1.091 V in 0.2 mol·L^?1 pH 4.4 acetate buffer solution. The GMP oxidation was enhanced in the presence of anionic surfactant in the ?lms. The results suggest that the surfactant molecules intercalate the LDH layers to preconcentrate GMP molecules and the RTIL showed good ionic conductivity. The experimental parameters were optimized, the kinetic parameters were investigated and the probable oxidation mechanism was proposed. Under the optimized conditions, the oxidation peak current was proportional to GMP concentration in the range from 5.0×10^?7 to 1.0×10^?4 mol·L^?1 with the correlation coefficient of 0.9987 and the detection limit was 1.0×10^?7 mol·L^?1. The RTIL/LDH‐SDS/GCE showed a good electrochemical response to the oxidation of GMP and would be developed into a new biosensor.     

Preparation of Molecularly Imprinted Electrochemical Sensor for Detection of Vincristine Based on Reduced Graphene Oxide/Gold Nanoparticle Composite Film

An innovative molecularly imprinted electrochemical sensor was fabricated based on reduced graphene oxide (RGO) and gold nanocomposite (Au) for rapid detection of vincristine (VCR). The RGO‐Au composite membrane was obtained via direct one‐step electrodeposition technique of graphene oxide (GO) and chloroauric acid (HAuCl₄) on the surface of a glassy carbon electrode (GCE) by means of cyclic voltammetry (CV) in the potential range between ?1.5 and 0.6 V in phosphate buffer solution (PBS) of pH 9.18, which is capable of effectively utilizing its superior electrical conductivity, larger specific surface area due to its synergistic effect between RGO and Au. The molecularly imprinted polymers (MIPs) were synthesized on the RGO‐Au modified glassy carbon electrode surface with VCR as the template molecular, methyl acrylic acid (MAA) as the functional monomer, and ethylene glycol maleic rosinate acrylate (EGMRA) as a cross‐linker. The performance of the sensor was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) in detail. Under the optimum conditions, the fabricated sensor exhibited a linear relationship between oxidation peak current and VCR concentration over the range of 5.0×10^?8–5.0×10^?6 mol·L ^minus;1 with a correlation coefficient of 0.9952 and a detection limit (S/N=3) of 2.6×10^minus;8 mol·L^minus;1. The results indicated that the imprinted polymer films exhibited an excellent selectivity for VCR. The imprinted sensor was successfully used to determine VCR in real samples with recoveries of 90% –120% by using the standard addition method.     

Preparation of Close‐Packed Silver Nanoparticles on Graphene to Improve the Enzyme Immobilization and Electron Transfer at Electrode in Glucose/O2 Biofuel Cell

In this study, chemical reduced graphene‐silver nanoparticles hybrid (AgNPs @CR‐GO ) with close‐packed AgNPs structure was used as a conductive matrix to adsorb enzyme and facilitate the electron transfer between immobilized enzyme and electrode. A facile route to prepare AgNPs @CR‐GO was designed involving in β ‐cyclodextrin (β ‐CD ) as reducing and stabilizing agent. The morphologies of AgNPs were regulated and controlled by various experimental factors. To fabricate the bioelectrode, AgNPs @CR‐GO was modified on glassy carbon electrode followed by immobilization of glucose oxidase (GOx ) or laccase. It was demonstrated by electrochemical testing that the electrode with close‐packed AgNPs provided high GOx loading (Γ =4.80 × 10⁻¹⁰ mol•cm⁻²) and fast electron transfer rate (k _s=5.76 s⁻¹). By employing GOx based‐electrode as anode and laccase based‐electrode as cathode, the assembled enzymatic biofuel cell exhibited a maximum power density of 77.437 μW •cm⁻² and an open‐circuit voltage of 0.705 V.     

Preparation, Electrochemical Behavior and Electrocatalytic Activity of a Copper Hexacyanoferrate Modified Ceramic Carbon Electrode

A copper hexacyanoferrate modified ceramic carbon electrode （CuHCF/CCE） had been prepared by two-step sol-gel technique and characterized using electrochemical methods. The resulting modified electrode showed a pair of well-defined surface waves in the potential range of 0.40 to 1.0 V with the formal potential of 0.682 V （vs. SCE） in 0.050 mol·dm^-3 HOAc-NaOAc buffer containing 0.30 mol·dm^-3 KCl. The charge transfer coefficient （a） and charge transfer rate constant （ks） for the modified electrode were calculated. The electrocatalytic activity of this modified electrode to hydrazine was also investigated, and chronoamperometry was exploited to conveniently determine the diffusion coefficient （D） of hydrazine in solution and the catalytic rate constant （kcat）. Finally, hydrazine was determined with amperometry using the resulting modified electrode. The calibration plot for hydrazine determination was linear in 3.0 × 10^-6--7.5 × 10^-4 mol·dm^-3 with the detection limit of 8.0 × 10^-7 molodm^-3. This modified electrode had some advantages over the modified film electrodes constructed by the conventional methods, such as renewable surface, good long-term stability, excellent catalytic activity and short response time to hydrazine.     

Rapid voltammetric determination of maltol in some foods and beverages using a poly(methylene blue)/graphene-modified glassy carbon electrode

A novel poly(methylene blue)/graphene composite glassy carbon electrode was fabricated and the electrochemical behavior of maltol at the modified electrode was studied by cyclic voltammetry. In phosphate-buffered solution, the modified electrode exhibited excellent electrocatalytic activity towards the electrochemical oxidation of maltol. Under optimized conditions, the oxidation peak current showed a linear relationship with the concentrations of maltol in the ranges of 8.00?×?10^?7 to 4.00?×?10^?5 and 4.00?×?10^?5 to 5.40?×?10^?4 mol L^?1, with a detection limit of 6.50?×?10^?8 mol L^?1. The performance of the developed method was validated in terms of linearity (r?=?0.9981 and 0.9955), recovery (97.0?99.3 %), reproducibility (relative standard deviations?≤?3.1 %, n?=?6), and robustness. The method shows excellent sensitivity, selectivity, and reproducibility and has been successfully applied to analyzing maltol in a wide variety of food products.     

The Determination of Salbutamol Sulfat Based on a Flow‐Injection Coupling Irreversible Biamperometry at Poly(aminosulfonic acid)‐Modified Glassy Carbon Electrode

Abstract

The present work describes the development of a simple and efficient method for electrochemical analysis determination of SBS using polymer film coated modified electrode. A glassy carbon electrode (GCE) is successfully modified with electropolymerized film of aminosulfonic acid (ASA) in pH 6.8 phosphate buffer solution (PBS). Cyclic voltammetry (CV) were used to study the electrochemical properties of the polymer film and the appropriate condition for electropolymerization process. The voltammetric behavior of SBS at the PASA GC CMEs has been investigated, the results suggest that the PASA GC CMEs have good effect of electrocatalytic oxidation action to SBS, also propose the mechanism toward SBS. The flow‐injection irreversible biamperometry analysis method was studied under the applied potential difference of 0 V to determinate SBS. In 0.1 mol l^?1 (pH 6.80) phosphate buffer solution, a sensitive and irreversible oxidation peak was obtained at the PASA GC CMEs. Under the optimum conditions, SBS can be determined from the range 2.0×10^?6 to 1.0×10^?3 mol · 1^?1 with the sampling frequency of 100 samples per hour. The detection limit for SBS is 6.5×10^?7 mol l^?1 and the RSD for 20 replicate determinations of 4.0×10^?5 mol l^?1 SBS is 1.85%. The method is simple, with high selective rapid and sensitive. The method is applied to the determination of SBS in the drug with satisfactory results. Moreover, the physiologically common interferents (i.e., sucrose, lactose, citric acid, and citrate) negligibly affected the response of SBS. The PASA GC CMEs film‐coated electrode exhibited a stable and sensitive response to salbutamol sulfat in the presence of electrocatalysis oxidation.     

Ensemble of carbon fiber ultra-microelectrodes modified with nanotubes, and its application to the determination of dopamine

An ensemble of carbon fibers ultra-microelectrode modified with carbon nanotubes (EUME-CNTS) has been constructed based on a thin carbon nanotubes film which was coated onto surfaces of carbon fibers of ultra-microelectrode. SEM micrographs illustrated the image of carbon nanotubes on the carbon fiber surface. The electrochemical characteristics of the EUME-CNTS has been investigated by cyclic voltammetry. The electrochemical properties of dopamine on this electrode were also studied, and the detection limit was found to be 2.0 × 10⁻⁹ mol·L⁻¹. Linear calibration plots were obtained for the oxidation peak current in a range 1.0 × 10⁻⁷–8.0 × 10⁻⁵ mol·L⁻¹. Correspondence: Xiuhua Liu, Kuaizhi Liu, Department of Chemistry and Chemical Engineering, Henan University, Henan Kaifeng 475001, P.R. China