三维有序金掺杂纳米TiO_2修饰电极用于抗肿瘤药物与DNA相互作用的研究

利用模板法在氧化铟锡(ITO)电极表面制备了三维有序多孔结构的金掺杂纳米Ti O2薄膜修饰电极(3DOM GTD/ITO),并在此修饰电极上成功固定小牛胸腺DNA(ct DNA),从而构建了一种新型的DNA生物传感器(DNA/3DOM GTD/ITO),并通过透射电镜(TEM)、扫描电镜(SEM)对修饰电极的表面形貌进行表征。采用电化学交流阻抗(EIS)法研究了ct DNA在3DOM GTD/ITO修饰电极表面的固定情况,结果表明,ct DNA已被成功地固定在3DOM GTD/ITO修饰电极表面。采用循环伏安法、微分脉冲伏安法等电化学方法研究了抗肿瘤药物槲皮素(Qu)在3DOM GTD/ITO修饰电极表面的电化学性质及与ct DNA的相互作用。结果表明,Qu在3DOM GTD/ITO修饰电极表面有1对准可逆的氧化还原峰,其氧化还原反应为2电子和2质子的转移过程。Qu可与固定在修饰电极上的ct DNA发生较强的结合作用,其结合常数(K)为3.61×106L/mol。循环伏安实验、紫外-可见吸收光谱、分子荧光光谱、圆二色性光谱均表明Qu与ct DNA之间的相互作用模式为嵌插作用。Qu与ct DNA的碱基结合具有序列选择性,对Qu与聚(d G-d C)及聚(d A-d T)的结合常数进行计算,得到结合常数比K(d G-d C)/K(d A-d T)=3.5,表明Qu与ct DNA发生嵌插作用时更倾向于结合在GC富集区域。     

槲皮素在聚谷氨酸修饰玻碳电极上的伏安行为及检测

制备了聚谷氨酸修饰玻碳电极,通过循环伏安法和差分脉冲伏安法研究了槲皮素在该修饰电极上的电化学行为。在pH 5.00的B-R缓冲液中,槲皮素在修饰电极上于0.28 V(vs Ag/AgCl)电位处产生一个灵敏的DPV阳极氧化峰,氧化峰电流与槲皮素的浓度在1.0×10-8～5×10-5 mol/L的范围内呈良好的线性关系,最低检测限为4.0×10-9 mol/L。实验表明,聚谷氨酸修饰电极可提高槲皮素的检测灵敏度,该电极用于芦丁水解产物中槲皮素的检测,回收率为103.4%～104.5%。     

槲皮素在聚离子液体膜修饰电极上的电化学行为及其测定

合成了1-[3'-(N-吡咯)丙基]-3-己基咪唑四氟硼酸盐离子液体,以其为单体,采用循环伏安法(CV)制备出聚离子液体膜修饰玻碳电极,经十二烷基硫酸钠溶液处理实现阴离子交换,获得聚离子液体疏水膜界面(PIL/GCE),利用扫描电子显微镜(SEM)和K_3Fe(CN)_6/K_4Fe(CN)_6探针表征了该修饰电极的表面形貌和电化学性能,通过伏安法研究了槲皮素在PIL/GCE电极界面上的电化学行为。结果发现:槲皮素在该修饰电极上只有一个不可逆的氧化峰,与裸玻碳电极相比,氧化峰电流显著增强。优化了实验条件如:聚合膜的厚度,pH,富集电位和富集时间等。在优化条件下,槲皮素的氧化峰电流与浓度在0.5~3.0μmol/L和3.0~20μmol/L范围类有良好的线性关系,检测限为0.2μmol/L。方法已用于中药中槲皮素的测定。     

槲皮素在氧化锆/石墨烯修饰玻碳电极上的电化学行为及检测

采用电沉积技术制备了氧化锆/石墨烯修饰的玻碳电极。利用循环伏安法研究了扫描速率和p H对槲皮素电化学行为的影响,结果表明,槲皮素在该修饰电极上的电极反应是扩散控制过程。采用示差脉冲伏安法测定槲皮素:在0.1 mol/L的磷酸盐缓冲溶液中(p H 7.0)槲皮素的氧化峰电流与其浓度在8.0×10-6~2.4×10-4mol/L范围内呈良好的线性关系,线性方程为ip(μA)=-0.1320c-6.1743,相关系数为-0.9913,检出限为2.0μmol/L(S/N=3)。修饰电极已用于实际样品的测定。     

纳米银自组装电极的制备及对高氯酸二茂铁的电化学响应

采用自组装的方法制备了纳米银粒子修饰金电极,并运用循环伏安法、交流阻抗谱探讨了该电极的电化学特性.研究了高氯酸二茂铁在该修饰电极上的直接电化学行为.实验结果表明,高氯酸二茂铁在该修饰电极上具有良好的电流响应.用示差脉冲法测定高氯酸二茂铁,其氧化峰电流与浓度在4.0×10-6～5.0×10-4 mol/L范围呈良好线性关系,线性方程为:Ip(μA)=0.0236c(μmol/L)-0.0975,线性相关系数为0.9982,检出限为2.3×10-7 mol/L(信噪比为3).     

槲皮素在聚L-络氨酸修饰电极上的电化学行为及测定

采用电聚合方法制备了聚L-络氨酸修饰电极。利用循环伏安法(CV)探究了pH值、扫描速率对槲皮素电化学行为的影响。用差分脉冲伏安法(DPV)对槲皮素进行测定。结果表明:聚L-络氨酸修饰电极在pH值为6.0的磷酸盐缓冲溶液中对槲皮素表现出良好的电催化能力。在6.21×10~(-5)～6.9×10~(-4) mol/L范围内槲皮素的浓度与相应的检测信号呈现出良好的线性关系,线性方程为:I(10~(-6) A)=-1.034 8-0.099 39c(10~(-4) mol/L),线性相关系数R=-0.987 87,检出限为2.07×10~(-5) mol/L(S/N=3)。电化学分析方法简易快捷、重现性和稳定性高。     

鸟嘌呤在铂纳米/壳聚糖/石墨烯修饰玻碳电极上的电化学行为及测定

制备了铂纳米/壳聚糖/石墨烯修饰电极。研究了鸟嘌呤(G)在修饰电极上的电化学行为。结果表明,该修饰电极对G的氧化具有明显的电催化作用。利用示差脉冲伏安法(DPV)对G进行检测,在0.1~10μmol/L浓度范围内,G的氧化峰电流和浓度成良好的线性关系,线性方程为I(μA)=2.08-1.92c(×10~(-5)mol/L),相关系数为0.9977,检测限为32 nmol/L(S/N=3)。该修饰电极用于血清样品中G的检测。     

电化学还原氧化石墨烯/纳米金-壳聚糖复合膜修饰玻碳电极对尿酸的灵敏测定

将氧化石墨烯(GO)在玻碳电极(GCE)表面进行直接电化学还原,再组装上纳米金-壳聚糖(AuNPCS)聚阳离子,形成了电化学还原氧化石墨烯/纳米金-壳聚糖(ERGO/AuNP-CS)复合膜修饰的玻碳电极。采用扫描电子显微镜(SEM)表征了不同修饰膜表面的形貌,探讨了其对尿酸(UA)分子的差分脉冲伏安(DPV)行为,发现ERGO/AuNP-CS复合膜对UA分子表现出显著的电催化氧化活性。在0.10 mol/L磷酸盐缓冲溶液(pH=6.5)中,扫速为100 mV/s时,此复合膜修饰电极的DPV响应与UA的浓度在0.05~110μmol/L范围内呈性关系,检测限为12.4 nmol/L(S/N=3)。此修饰电极具有良好的选择性、重现性和稳定性,可应用于人体血清和尿液样品中UA的测定,回收率达到93.8%~104.1%。结果与分光光度法和尿酸酶试剂盒法相符。     

生物样品中小檗碱的电化学分析新方法

由于小檗碱氧化电位较高(>1.1 V vs. Ag/AgCl),进行生物样品中小檗碱的选择性电化学分析具有挑战性。基于溴百里酚蓝(BTB)和小檗碱的分子间非共价作用,通过单壁碳纳米管(SWNTs)将BTB修饰在电极表面并通过电化学聚合产生poly-BTB,利用聚BTB(poly-BTB)电极过程可逆以及氧化还原电位低的特点,以poly-BTB同时作为小檗碱的识别元件和电化学探针建立了小檗碱的电化学分析新方法。循环伏安和电化学阻抗谱结果表明,poly-BTB和小檗碱的分子间作用导致小檗碱结合在poly-BTB/SWNTs修饰电极表面,从而引起修饰电极的峰电流下降。在最优化的实验条件下,poly-BTB/SWNTs修饰电极的电流下降率和小檗碱的浓度在0.05～1μmol/L和1～100μmol/L范围内呈良好线性关系,检测限为0.022μmol/L。动物实验结果表明,该方法对生物样品具有很好的选择性,可用于血浆和肝脏匀浆中小檗碱含量的测量,为小檗碱相关的生理病理研究提供了一种简单有效的方法。     

碳量子点增敏的葡萄糖分子印迹电化学传感器

以3-氨基苯硼酸为功能单体,葡萄糖为模板分子,在碳量子点和壳聚糖修饰的玻碳电极表面电聚合生成分子印迹聚合物膜,构建了无酶分子印迹电化学传感器,用于葡萄糖的高灵敏测定。采用循环伏安法(CV)、交流阻抗法(EIS)和差分脉冲伏安法(DPV)研究传感器的电化学特性及分析特性。在最优条件下,DPV电流响应的变化值与葡萄糖浓度在0.1～1.0μmol/L和1.0～300μmol/L范围内分别呈现良好的线性关系,线性方程分别为ΔI_p(μA)=3.792+23.41C (R²=0.9968)和ΔI_p(μA)=28.18+0.1316C (R2=0.9914),检出限为0.034μmol/L (3σ/k)。将此传感器应用于体液中葡萄糖的测定,回收率为95.1%～106.8%。     

A Selective Voltammetric Method for Detecting Dopamine at Quercetin Modified Electrode Incorporating Graphene

The development of a quercetin‐graphene composite‐modified glassy carbon electrode (Qu/GH/GCE) for the selective and sensitive detection of dopamine (DA) is described in this paper. To fabricate the Qu/GH/GCE, graphene (GH) was first coated onto the surface of a glassy carbon electrode (GCE) and then quercetin (Qu) was electrodeposited on the GH matrix. Transmission electron microscopy (TEM) was used to characterize the morphology of the obtained GH and Qu/GH, and the electrochemical properties of the modified electrode were studied using electrochemical techniques. The as‐prepared Qu/GH/GCE occupied a synthetic property between GH and Qu. The common overlapped electrochemical oxidation peaks of DA and AA were completely separated and a remarkable increasing electron‐oxidation current of DA occurred on the Qu/GH/GCE, which enabled the sensitive and selective electrochemical detection of DA in the presence of ascorbic acid (AA) with peak difference of ca. 452 mV between DA and AA. The peak current obtained at 0.174 V (vs. saturated calomel electrode, SCE) from differential pulse voltammetry (DPV) is linearly dependent on the DA concentration in the range from 3.0×10^?8 to 4.0×10^?4 mol/L with a detection limit of 1.0×10^?8 mol/L. Furthermore, the Qu/GH/GCE exhibits good reproducibility and stability, and has been used for the determination of DA in samples of rat’s striatum tissue with satisfactory results.     

A quercetin-modified biosensor for amperometric determination of uric acid in the presence of ascorbic acid

The present work reports a quercetin-modified wax-impregnated graphite electrode (Qu/WGE) prepared through an electrochemical oxidation procedure in quercetin-containing phosphate buffer solution (PBS), for the purpose of detecting uric acid (UA) in the presence of ascorbic acid (AA). During modification quercetin was oxidized to the corresponding quinonic structure, and in the blank buffer solution the electrodeposited film exhibits a voltammetric response anticipated for the surface-immobilized quercetin. Retarding effect of the film towards the reaction of anionic species was found; therefore the pH of sample solutions was selected to ensure the analyte in molecular form. At suitable pHs the Qu/WGE shows excellent electrocatalytic effect towards the oxidation of both AA and UA, and separates the voltammetric signal of UA from AA by about 280 mV, allowing simultaneous detection of these two species. A linear relation between the peak current and concentration was obtained for UA in the range of 1-50 μM in the presence of 0.5 mM AA, with a detection limit 1.0 μM (S/N = 3). This sensor was stable, reproducible and outstanding for long-term use.     

槲皮素在氧化锆修饰玻碳电极上的伏安行为及检测

制备了氧化锆修饰的玻碳电极,采用示差脉冲伏安法和循环伏安法探究了槲皮素在该电极上的电化学行为。结果表明,制备的修饰电极在pH=7.00的磷酸盐缓冲溶液（PBS）中对槲皮素的氧化还原具有明显的电催化作用。采用槲皮素的氧化峰电流作为分析信号。在浓度为2.5×10-8~5×10-5 mol/L的范围内,氧化峰电流和浓度成良好的线性关系,线性方程为ip（μA）=0.0825c-9.861 84,检出限为5.35×10-9 mol/L。     

聚铬黑T修饰电极检测亚硝酸盐的研究

利用电化学聚合法将铬黑T修饰到玻碳电极表面,制得聚铬黑T修饰电极。该修饰电极对亚硝酸盐的电化学氧化具有明显的催化作用,这种催化作用主要是由于聚铬黑T薄膜与带负电荷的亚硝酸盐离子的静电相互作用,导致亚硝酸盐离子富集在电极表面/溶液界面,显著增强了亚硝酸盐的氧化电流。电子传输系数α为0.735。选用0.85V作为工作电压,对亚硝酸盐进行安培检测,在0.05μmol/L～1.0 mmol/L和1.0～20.0 mmol/L两个浓度范围内呈现良好的线性关系,检测限达到0.01μmol/L。且该修饰电极有良好的重现性和稳定性。将该修饰电极用于泡菜中亚硝酸盐的测定,获得了满意的结果。     

Electrochemical determination of quercetin by self-assembled platinum nanoparticles/poly(hydroxymethylated-3,4-ethylenedioxylthiophene) nanocomposite modified glassy carbon electrode

A simple and sensitive platinum nanoparticles/poly(hydroxymethylated-3,4-ethylenedioxylthiophene)nanocomposite(PtNPs/PEDOT-MeOH) modified glassy carbon electrode(GCE) was successfully developed for the electrochemical determination of quercetin.Scanning electron microscopy and energy dispersive X-ray spectroscopy results indicated that the PtNPs were inserted into the PEDOTMeOH layer.Compared with the bare GCE and poly(3,4-ethylenedioxythiophene)(PEDOT) electrodes,the PtNPs/PEDOT-MeOH/GCE modified electrode exhibited a higher electrocatalytic ability toward the oxidation of quercetin due to the synergic effects of the electrocatalytic activity and strong adsorption ability of PtNPs together with the good water solubility and high conductivity of PEDOT-MeOH.The electrochemical sensor can be applied to the quantification of quercetin with a linear range covering0.04-91 μmol L~(-1) and a low detection limit of 5.2 nmol L~(-1).Furthermore,the modified electrode also exhibited good reproducibility and long-term stability,as well as high selectivity.     

Preparation of Novel Arrays Silver Nanoparticles Modified Polyrutin Coat‐Paraffin‐Impregnated Graphite Electrode for Tyrosine and Tryptophan's Oxidation

A novel array silver nanoparticles and Rutin complex film modified paraffin‐impregnated graphite electrode was proposed in this work (denoted as Ag/Rutin/WGE). The characteristics were investigated by the field emission scanning electron microscopy (FE‐SEM), infrared spectra (IR), UV‐visible (UV), X‐ray photoelectron spectroscopy (XPS) and electrochemical techniques. Silver ions were gradually chelated by polyrutin film at 4′‐oxo‐5′‐OH and 5‐OH‐4‐oxo sites accompanying adsorption, then. Silver nanoparticles were highly‐dispersed electrodeposited on polyrutin film. The electrochemical behaviors of tyrosine (Tyr) and tryptophan (Trp) were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The Ag/Rutin/WGE electrode shows overlapping catalysis for the oxidation of Tyr and Trp. The linear response of Tyr and Trp were 0.3–10.0 and 0.7–70.0 μM with detection limit of 0.07 and 0.1 μM in a signal‐to‐noise ratio of 3.     

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.