基于纳米ZnO/壳聚糖复合膜DNA电化学传感器用于HIV基因的免标记检测

以室温固相合成法制备纳米ZnO,通过壳聚糖(CHIT)的成膜效应将纳米ZnO固定在玻碳电极(GCE)表面,制得的ZnO/CHIT/GCE电极成为DNA固定和杂交的良好平台。DNA的固定和杂交通过电化学交流阻抗进行表征。以电化学交流阻抗免标记法检测目标DNA,固定于电极表面的DNA探针与目标DNA杂交后使电极表面的电子传递电阻增大,以此作为检测信号可以高灵敏度地测定目标DNA。电化学阻抗谱检测人类免疫缺陷病毒(HIV)基因片段的线性范围为2.0×10-11~2.0×10-6mol/L,检出限为2.0×10-12mol/L。     

己硫醇二茂铁复合金纳米粒子修饰电极对多巴胺的催化性能研究

将自行合成的己硫醇二茂铁自组装于金纳米粒子表面,获得己硫醇二茂铁复合金纳米粒子（Au@S（CH2）6Fc）。采用滴涂法将制备的复合纳米粒子固定于玻碳电极表面,制备Au@S（CH2）6Fc修饰电极,采用循环伏安法对修饰电极的电化学性能进行考察。将制备的修饰电极用于对神经递质多巴胺（DA）的催化氧化性能研究。结果表明,该修饰电极对DA具有显著的催化氧化作用,线性范围为1.0×10^-6-2.6×10^-3mol/L,检出限为3.0×10^-7mol/L。     

纳米金/3-氨丙基-三乙氧基硅烷修饰传感器电化学检测NO-2

将3-氨丙基-三乙氧基硅烷（ATS）修饰在玻碳电极表面,再自组装一层纳米金,制备了一种新型NO2^-的电化学传感器。该修饰电极对NO2^-有较好的催化作用。在pH为3时,NO2^-的氧化峰电流与其浓度在5．0×10^-7～1．0×10^-3mol／L范围内呈良好的线性关系,检出限可达2．0×10^-7mol／L。方法具有较高的灵敏度和较好的重现性。     

DNA在Mg/聚2,6-吡啶二甲酸膜上的固定和杂交及其PAT基因片段的电化学阻抗谱测定

以静电吸附法使Mg²⁺修饰于玻碳电极(GCE)上电聚合的2,6-吡啶二甲酸膜(PDC)上, 制得的Mg/PDC/GCE电极, 成为DNA固定及杂交的良好平台. 应用微分脉冲伏安法和电化学阻抗谱对DNA的固定和杂交进行表征. 以电化学阻抗谱免标记法检测目标DNA比以亚甲基蓝为指示剂的微分脉冲伏安法有更高的灵敏度. 固定于电极表面的DNA探针与互补单链DNA杂交后使电负性的[Fe(CN)₆]^3-/4-的表面电子传递电阻值显著增大, 以此作为检测信号可以高灵敏度地测定目标DNA. 电化学阻抗谱检测转基因植物外源PAT基因片段, 线性范围为1.0×10^-9 ~ 1.0×10^-5 mol/L, 检测限为3.4×10^-10 mol/L.     

纳米金固定辣根过氧化物酶的碳纳米管修饰第3代过氧化氢传感器的研究

将纳米金吸附辣根过氧化物酶（HRP）固定在多壁碳纳米管（MWNT）修饰的铂（Pt）电极上,利用MWNT对HRP的直接电化学催化特性及纳米金对蛋白质的强吸附能力制备了第3代H2O2生物传感器。实验结果表明,HRP在MWNT／Pt电极表面能进行有效和稳定的直接电子转移,HRP保持了其对H2O2还原的生物电催化活性,而且能快速（3S）地响应H2O2浓度的变化。HRP在修饰电极上的表观吸附量（Tr）为7．3×10^-10mol／cm^2,异相电子转移常数（Ks）为1．23s^-1。该传感器在-300mV时对H2O2响应的线性范瑚为1×10^-5～1×10^-3 mol／L（r=0．9968,n=4）。     

发夹结构DNA探针用于检测白血病PML/RARA融合基因的电化学传感器的研究

基于急性早幼粒细胞白血病（acute promyelocytic leukemia,APL）中PML／RARA（promyelocytic leukemia／retinoic acid receptor alpha）融合基因的碱基序列,设计了一种新型发夹结构DNA电化学探针,并将此探针固定在玻碳电极表面,采用自行合成的硝基吖啶酮（NAD）作杂交指示剂,应用循环伏安法与差分脉冲伏安法实现了对人工合成的APLPML／RARA融合基因的检测,同时对检测条件进行优化。结果表明,在pH7．0Tris—HCl缓冲液中,杂交前后NAD氧化峰电流差值与靶标链浓度在2．0×10^-8～1．0×10^-7mol·L^-1范围内呈良好的线性关系,检出限为3．0×10^-9mol·L^-1。     

米托蒽醌分子印迹聚邻氨基酚敏感膜传感器的研制

在弱酸性条件下,在金电极上以邻氨基酚为单体和交联剂,米托蒽醌为模板分子,用循环伏安法电聚合成米托蒽醌分子印迹聚邻氨基酚敏感膜传感器。该传感器对米托蒽醌具有良好的选择性和敏感度,米托蒽醌浓度分别在2.0×10^-7—1.0×10^-5mol／L及1.0×10^-5—5.0×10^-5mol／L范围内与峰电流减小量呈线性关系,检出限为1.2×10^-7mol／L。本文同时对分子印迹膜的结构和性能进行了探讨与研究。     

诺必擂停的电化学性质研究及示差脉冲伏安法测定

研究了抗癌药物诺必擂停在玻碳电极上的电化学行为及其反应机理,建立了一种灵敏的测定诺必擂停的分析方法。实验结果表明,在pH 2.0的磷酸盐缓冲溶液中,诺必擂停在-0.905 V电位处产生灵敏的还原峰,该还原峰电流与诺必擂停的浓度在8.21×10^-6-1.09×10^-4mol/L范围内呈现良好的线性关系（r=0.9923）,检出限为5.47×10^-6mol/L。该法已用于人血清中诺必擂停的测定,回收率在94.5%-104.4%之间。     

对氯酚在碳纳米管修饰玻碳电极上的电化学行为研究

研究了对氯酚在多壁碳纳米管修饰玻碳电极（MWNTs/GC）上的电化学行为。MWNTs/GC电极对对氯酚具有良好的电催化作用,相比玻碳电极对氯酚的氧化峰电位负移76 mV,峰电流达到玻碳电极上的8倍。通过线性扫描伏安法研究了富集时间、溶液pH和扫描速率对对氯酚氧化的影响。并采用计时电流法研究了氧化峰电流与对氯酚的浓度关系,结果显示峰电流与对氯酚的浓度在2.0×10^-7-2.0×10^-4mol/L范围内呈良好线性关系,检出限为8.8×10-8mol/L（S/N=3）。放置7 d后,对氯酚在碳纳米管上的峰电流仍能达到最初电流的96.2%,表明电极的稳定性较好。     

普鲁士蓝和茈四甲酸二酐衍生物膜修饰的过氧化氢生物传感器

以玻碳电极（GCE）为基底,采用恒电位法沉积一层普鲁士蓝（PB）,然后将j芑四甲酸二酐衍生物（PTC-NH,）自组装到其表面,形成既带氨基功能团,又可有效防止PB渗漏的导电膜。通过静电吸附和共价键合作用固定纳米金和辣根过氧化物酶（HRP）的复合物,从而制得性能优良的过氧化氢（H2O2）生物传感器。采用循环伏安法（CV）和计时电流法,考察了传感器的电化学性能。实验表明,本传感器具有灵敏度高、线性范围宽、检出限低、稳定性好、抗干扰能力强等特点。其线性范围为2．0×10^-6～1．4×10^-5mol／L;检出限为8．3×10^-7mol／L（S／N=3）。     

Direct electrochemistry of glucose oxidase immobilized on porous carbon nanofiber/room temperature ionic liquid/chitosan composite film and its biosensing application

The direct electron transfer of glucose oxidase (GOD) immobilized on a composite matrix based on porous carbon nanofibers (PCNFs), room-temperature ionic liquid (RTIL), and chitosan (CHIT) underlying on a glassy carbon electrode was achieved. The combination of the PCNFs, RTIL, and CHIT provided a suitable microenvironment for GOD to transfer electron directly. In deaerated buffer solutions (pH 7.0), the cyclic voltammetry of the GOD/PCNFs/RTIL/CHIT composite films showed a pair of well-defined redox peaks with the formal potential of −0.45 V (vs. SCE). The synergistic effort of the PCNFs, RTIL, and CHIT also promoted the stability of GOD in the composite film and retained its bioactivity.     

Label-Free Detection of DNA Hybridization Based on MnO2 Nanoparticles

Abstract

Nano-MnO₂/chitosan composite film modified glassy carbon electrode (MnO₂/CHIT/GCE) was fabricated and a DNA probe was immobilized on the electrode surface. The immobilization and hybridization events of DNA were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The EIS was applied to the label-free detection of the target DNA. The human immunodeficiency virus (HIV) gene fragment was successfully detected by this DNA electrochemical sensor. The dynamic detection range was from 2.0 × 10^?11 to 2.0 × 10^?6 mol/L, with a detection limit of 1.0 × 10^?12 mol/L.     

MnO2电沉积直立碳纳米管制备超级电容器的研究

以直立碳纳米管为基底,以pH=6.0的0.1mol/L Na2SO4 为底液,采用电化学沉积法在0.2 mol/L Mn(CH3COO)2溶液中制备了直立碳纳米管与二氧化锰复合材料。SEM测试结果表明复合材料表面呈现多孔状结构。通过循环伏安,恒流充放电,交流阻抗等电化学方法对复合材料修饰电极进行电容性质测试。实验结果表明,在1mol/L KCl 溶液中,0-0.6V(vs. 银/氯化银参比)电位窗口内此复合材料表现出优良的超电容性能。直立碳纳米管电极的比电容为16 F/g,在碳纳米管表面沉积上二氧化锰修饰层后,此复合材料电极的比电容增大至330 F/g,比电容量大幅提升近20倍。同时扫描200圈后,直立碳纳米管与二氧化锰复合材料的循环伏安曲线变化很小,说明其具有相当好的循环寿命和电容稳定性能。     

Supramolecular architectures of beta-cyclodextrin-modified chitosan and pyrene derivatives mediated by carbon nanotubes and their DNA condensation

Beta-cyclodextrin-modified chitosan 1 was synthesized via the Schiff base reaction between 6-O-(4-formylphenyl)-beta-cyclodextrin and chitosan (CHIT), and then the supramolecular dyad assemblies 2 and 3 were respectively fabricated from the subunit 1 through the inclusion of adamantane-modified pyrene into the beta-cyclodextrin cavity and the wrapping of a CHIT chain on multiwalled carbon nanotubes (MWCNTs). The water-soluble dyad 3 further interacted with adamantane-modified pyrene, forming a stable triad assembly 4. They were extensively characterized by NMR, thermogravimetric analysis, UV-vis, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy (AFM). Furthermore, the DNA condensation abilities of 1-4 were validated by AFM and dynamic light scattering, which indicates that the DNA-condensing capability of CHIT can be pronouncedly improved by either the pyrene grafts or the MWCNT medium. The cooperation between cationic and aromatic groups as well as the dispersion of CHIT agglomerates by MWCNTs are the key factors to enhance DNA condensation of cationic polymers.     

Multiwalled Carbon Nanotubes‐Chitosan Modified Single‐Use Biosensors for Electrochemical Monitoring of Drug‐DNA Interactions

A multiwalled carbon nanotubes (CNT)‐chitosan (CHIT) modified pencil graphite electrode (CNT‐CHIT/PGE) was developed for the first time herein for electrochemical monitoring of the interaction of an anticancer drug, mitomycin C (MC) and DNA. The characterization of unmodified PGE, CHIT/PGE, CNT/PGE and CHIT‐CNT/PGE were performed by scanning electron microscopy and cyclic voltammetry techniques. The oxidation signals of MC and guanine were measured before and after interaction at the surface of CNT‐CHIT/PGEs using differential pulse voltammetry. Electrochemical impedance spectroscopy technique was also successfully utilized for monitoring of the interaction process at the surface of CNT‐CHIT/PGEs in different interaction times.     

Electrochemical sensing of DNA immobilization and hybridization based on carbon nanotubes/nano zinc oxide/chitosan composite film

A novel electrochemical DNA biosensor based on zinc oxide （ZnO） nanoparticles and multi-walled carbon nanotubes （MWNTs） for DNA immobilization and enhanced hybridization detection is presented. The MWNTs/nano ZnO/chitosan composite film modified glassy carbon electrode （MWNTs/ZnO/CHIT/GCE） was fabricated and DNA probes were immobilized on the electrode surface. The hybridization events were monitored by differential pulse voltammetry （DPV） using methylene blue （MB） as an indicator. The sensor can effectively discriminate different DNA sequences related to PAT gene in the transgenic corn, with a detection limit of 2.8× 10^-12 mol/L of target sequence.     

Direct electrochemistry of glucose oxidase immobilized on NdPO4 nanoparticles/chitosan composite film on glassy carbon electrodes and its biosensing application

The direct electrochemistry of glucose oxidase (GOx) immobilized on a composite matrix based on chitosan (CHIT) and NdPO(4) nanoparticles (NPs) underlying on glassy carbon electrode (GCE) was achieved. The cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the modified electrode. In deaerated buffer solutions, the cyclic voltammetry of the composite films of GOx/NdPO(4) NPs/CHIT showed a pair of well-behaved redox peaks that are assigned to the redox reaction of GOx, confirming the effective immobilization of GOx on the composite film. The electron transfer rate constant was estimated to be 5.0 s(-1). The linear dynamic range for the detection of glucose was 0.15-10 mM with a correlation coefficient of 0.999 and the detection limit was estimated at about 0.08 mM (S/N=3). The calculated apparent Michaelis-Menten constant was 2.5 mM, which suggested a high affinity of the enzyme-substrate. The immobilized GOx in the NdPO(4) NPs/CHIT composite film retained its bioactivity. Furthermore, the method presented here can be easily extended to immobilize and obtain the direct electrochemistry of other redox enzymes or proteins.     

镧掺杂的二氧化锰/碳纳米管电化学超级电容器复合电极

尽管在二氧化锰/多壁碳纳米管（MnO₂/MWCNTs）上获得了较高的比电容,低电导率仍是制约MnO₂担载量或膜厚度提高的主要障碍.另一个问题是MnO₂/MWCNTs的循环稳定性远低于活性炭.所以截止到目前这一新型材料的应用仍然受到很大的限制.本文采用原位还原的方法制备镧掺杂二氧化锰/多壁碳纳米管电化学超级电容器复合电极材料.分别通过透射电镜（TEM）、扫描电镜（SEM）、X射线衍射（XRD）和傅里叶变换红外（FTIR）光谱等技术对这些复合材料的形貌与结构进行了分析.采用循环伏安法、恒电流充放电法和交流阻抗法对其进行了电化学性能的研究.研究结果表明,通过还原MnO₄^-可以在MWCNTs上形成La掺杂MnO₂复合材料.La掺杂降低了复合电极的电阻,这是因为La的引入可以增大MnO₂的晶格缺陷,从而提高材料的电导率以及电极的电化学性能.因此La掺杂是克服MnO₂本征导电性差的有效途径之一.掺杂La可以在不增大电极电阻的情况下提高MnO₂的担载量或膜厚度.La掺杂的更重要的作用是使以MnO₂/MWCNTs作电极的对称电化学超级电容器的循环性能得到显著改善.此外,La掺杂也使复合电极的比电容得到一定程度的提高.     

固载于壳聚糖-纳米金复合膜修饰玻碳电极上的葡萄糖氧化酶的直接电化学研究及其生物传感应用

通过将葡萄糖氧化酶固载于壳聚糖-纳米金复合膜内所构置的传感器,实现了葡萄糖氧化酶的直接电化学,并采用循环伏安法与电化学阻抗法对修饰电极进行了表征。研究表明：在除氧缓冲溶液中,葡萄糖氧化酶-壳聚糖-纳米金复合膜修饰电极表现出一对良好的氧化还原峰,这对峰归因于葡萄糖氧化酶的氧化还原,证明葡萄糖氧化酶被成功固载于复合膜内。电子传递速率常数为15.6 s-1,说明葡萄糖氧化酶的电活性中心与电极之间的电子传递很快。将壳聚糖与纳米金相结合还提高了葡萄糖氧化酶在复合膜内的稳定性并保持其生物活性,并可以用于葡萄糖检测。计算得到其表观米氏常数为10.1 mmol·L-1。而且,该生物传感器可以用于血样中葡萄糖含量的测定。