无标记DNA在氨基改性导电聚吡咯表面的固定/杂交

通过吡咯(Py)与其衍生物——6-吡咯己胺(PyHA)的共聚物聚(吡咯-co-6-吡咯己胺)[poly(Py-co-PyHA)]的合成研究,并采用电化学循环伏安法来考察体系的电化学活性.在缓冲溶液中,由于探针DNA链上的负电荷与共聚物分子链上的正电荷之间存在强烈的静电吸引力,使得DNA能够固定在导电聚合物膜上.实验结果证明,目标DNA和聚吡咯薄膜之间不存在非特异性吸附,而能和探针DNA进行顺利杂交.此结果为以后研究更为敏感的DNA固定及导电聚合物敏感膜提供了实验基础.     

两种C60吡咯环多羧基衍生物自组装膜的制备及其光电转换性质研究

在ITO(indium-tin-oxide)透明电极和石英基片上,分别制备了两种C₆₀吡咯环多羧基衍生物的自组装膜,并用接触角、紫外光谱和电化学循环伏安进行表征.测定了这两种自组装膜体系的光电转换性质,研究了电子受体、偏压和光强等因素对它的影响.     

硫醇自组装膜对金电极上吡咯电化学聚合的影响

用电化学聚合法在多种烷基硫醇自组装膜修饰金电极上制备了聚吡咯.通过计时安培法、循环伏安法和交流阻抗技术研究了自组装膜的烷基链长和端基功能团对吡咯聚合过程和性质的影响.当自组装膜较完美时,聚吡咯沉积在自组装膜表面;而当自组装膜有一定缺陷时,吡咯在针孔处成核,然后继续生长并完全覆盖在自组装膜表面.研究结果表明,烷基硫醇的链越短,吡咯聚合越容易;疏水的烷基硫醇自组装膜有利于聚吡咯在电极表面的生长.     

导电聚吡咯共聚物薄膜的功能基团种类对蛋白质吸附的影响

导电聚合物由于其优越的稳定性和电化学性质,一直是蛋白质芯片敏感膜的研究热点.采用化学氧化聚合法分别制备出氨基和羧基功能化导电聚吡咯共聚物薄膜,通过调节体系单体比例(体积比)来改变导电共聚物的化学结构.采用傅里叶变换红外光谱表征了共聚物的化学组成,利用电化学循环伏安法考察共聚物薄膜的电化学活性变化.在此基础上,采用表面等离子谐振生化分析仪原位考察了牛血清白蛋白(BSA)在共聚物薄膜上的吸附动力学过程.由于共聚物薄膜上的功能基团的种类和含量不同,导致BSA吸附动力学和吸附量的差异.可以明显看出,蛋白质更容易在具有高的氨基密度或低的羧基密度的导电聚吡咯薄膜上进行吸附,随着氨基基团含量的增加,BSA在聚合物薄膜上的吸附量增大.相反,随着羧基基团含量的增大,BSA在共聚物薄膜上的吸附量减小.通过上述方法,可以控制蛋白质在导电聚合物上的吸附行为,进而为构建出更为敏感的、可精确控制的蛋白质芯片奠定基础.     

DNA在氨基功能化偶氮苯自组装膜表面的固定

采用简单快速的方法制备出将DNA固定在其表面的单分子层敏感膜.首先采用表面自组装技术将硅氧烷基偶氮苯衍生物H2NAzoCONHC3Si(OCH3)3(APDA-N-TMSPBA)组装在硅表面,在详细考察单分子层薄膜的化学结构、表面浸润性和分子表面形貌之后,又通过紫外吸收光谱(UV)在位考察了硅氧烷基偶氮苯衍生物的光学异构特性.在DNA在自组装薄膜固定后,X光电子能谱仪(XPS)结果显示出现了明显的磷元素信号,表明DNA分子可以成功固定在自组装膜表面.     

基于巯基自组装单层膜的日本血吸虫石英晶体微天平免疫传感器

应用自组装膜技术在压电石英晶振金电极表面自组装一带羧基的巯基丙酸单层膜,通过盐酸1-乙基-3-(3-二甲基氨基丙基)碳二亚胺及N-羟基琥珀酰亚胺共价固定32KD的日本血吸虫分子抗原(SjAg32),设计了石英晶振微天平免疫传感器,用于测定日本血吸虫抗体.比较了巯基自组装单层膜与HEMA-MMA共聚物涂层修饰的石英晶振在溶液中的振荡行为,发现巯基自组装单层膜修饰的石英晶振稳定快,且稳定性好.在优化条件下,测得IRS(49-2000)的滴度为1:1500.此外,对不同程度血吸虫感染的兔血清进行了测试,结果表明,该传感器能较好地定量区别血吸虫感染程度.     

聚合物微相分离诱导聚合物功能化碳纳米管的自组装

利用自组装的方法实现碳纳米管的有序排列对制备碳纳米管基复合材料至关重要.将聚4-乙烯基吡啶修饰的碳纳米管与含有羧基的接枝共聚物聚丙烯酸-g-聚甲基丙烯酸甲酯(PAA-g-PMMA)相混合,由于吡啶基团与羧基之间的氢键作用,在聚合物微相分离的过程中,将诱导形成碳纳米管的有序排列,得到一种基于碳纳米管自组装的蜂窝状膜.     

苯胺与吡咯共聚物空心球的自组装制备及性能

以碱性溶液为反应介质,苯胺和吡咯为单体,采用稀释聚合法制备苯胺-吡咯共聚物自组装空心微球.研究了搅拌条件、共聚单体摩尔比、聚合反应介质和聚合时间对共聚物形貌的影响.采用扫描电子显微镜、透射电子显微镜、红外光谱、广角X射线衍射、热重分析仪和四探针技术表征了共聚物的形貌、结构和性能.研究结果表明,聚合反应条件对共聚物的形貌有重大影响,通过调整聚合反应条件,可以实现共聚物形貌的有效调控.共聚单体总摩尔浓度为0.05 mol/L,氨水溶液作为反应介质,在静态条件下反应24 h可以得到尺寸均一、平均外直径为610～863 nm,壳厚144～162 nm的自组装共聚物空心微球.同时,研究了共聚物对银离子的吸附性能,结果表明共聚物对银离子有还原作用,吸附后共聚物表面有纳米银的生成.     

两种C60吡咯环多羧基衍生物自组装膜的制备及其光电转换 …

在ＩＴＯ透明电极和石英基片上,分别制备了两种Ｃ６０吡咯环多羧基衍生物的自组装膜,并用接触角、紫外光谱和和电化学循环伏安进行表征,测定限这两种自装膜体系的光电转换性质,研究了电子受体、偏压和光强等因素对它的影响。     

以乙二胺为分子绳索的C60自组装单层膜和双层膜的激光质谱研究

富勒烯的固体薄膜一般分为气相沉积膜、液相沉积膜、LB(Langmuir Blodgett)膜和化学自组装膜.化学自组装膜是通过特定的化学反应,将富勒烯通过化学键固定于基片上而形成的膜.     

Highly Sensitive Functionalized Conducting Copolypyrrole Film for DNA Sensing and Protein‐resistant

In order to exploit the applications of polypyrrole (PPy) derivatives in biosensors and bioelectronics, the different immobilization mechanisms of biomolecules onto differently functionalized conducting PPy films are investigated. Pyrrole and pyrrole derivatives with carboxyl and amino groups were copolymerized with ω‐(N‐pyrrolyl)‐octylthiol self‐assembled on Au surface by the method of the chemical polymerization to form a layer of the copolymer film, i.e., poly[pyrrole‐co‐(N‐pyrrolyl)‐caproic acid] (poly(Py‐co‐PyCA)) and poly[pyrrole‐co‐(N‐pyrrolyl)‐hexylamine] (poly(Py‐co‐PyHA)), in which the carboxyl groups in poly(Py‐co‐PyCA) were activated to the ester groups. Based on the structure characteristics, the immobilization/hybridization of DNA molecules on PPy, poly(Py‐co‐PyCA) and poly(Py‐co‐PyHA) were surveyed by cyclic voltammograms measurements. For differently functionalized copolymers, the immobilization mechanisms of DNA are various. Besides the electrochemical properties of the composite electrodes of PPy and its copolymers being detected before and after bovine serum albumin (BSA) adsorption, the kinetic process of protein binding was determined by surface plasmon resonance of spectroscopy. Since few BSA molecules could anchor onto the PPy and its copolymers surfaces, it suggests this kind of conducting polymers can be applied as the protein‐resistant material.     

Electrochemical impedance sensing of DNA hybridization on conducting polymer film-modified diamond

The impedimetric sensing of DNA hybridization on polyaniline/polyacrylate (PANI/PAA)-modified boron-doped diamond (BDD) electrode has been investigated. An ultrathin film of PANI-PAA copolymer was electropolymerized onto the diamond surfaces to provide carboxylic groups for tethering to DNA sensing probes. The electrochemical impedance and the intrinsic electroactivity of the polymer-diamond interface were analyzed after the hybridization reaction with target and non-target DNA. The impedance measurement shows changes in the impedance modulus as well as electron-transfer resistance at the stage of probe DNA immobilization (single-strand), as well as after hybridization with target DNA (double-strand). DNA hybridization increases the capacitance of the polymer-DNA layer and reduces the overall impedance of the DNA-polymer-diamond stack significantly. The polymer-modified BDD electrode shows no detectable nonspecific adsorption, with good selectivity between the complementary DNA targets and the one-base mismatch targets. The detection limit was measured to be 2 x 10(-8) M at 1000 Hz. Denaturing test on the hybridized probe and subsequent reuse of the probe indicates chemical robustness of the sensor. Our results suggest that electropolymerization followed by the immobilization of biomolecules is a simple and effective way of creating a functional biomolecular scaffold on the diamond surface. In addition, label-free electrochemical impedance method can provide direct and noninvasive sensing of DNA hybridization on BDD.     

Investigation of SPR and electrochemical detection of antigen with polypyrrole functionalized by biotinylated single-chain antibody: A review

An electrochemical label-free immunosensor based on a biotinylated single-chain variable fragment (Sc-Fv) antibody immobilized on copolypyrrole film is described. An efficient immunosensor device formed by immobilization of a biotinylated single-chain antibody on an electropolymerized copolymer film of polypyrrole using biotin/streptavidin system has been demonstrated for the first time. The response of the biosensor toward antigen detection was monitored by surface plasmon resonance (SPR) and electrochemical analysis of the polypyrrole response by differential pulse voltammetry (DPV). The composition of the copolymer formed from a mixture of pyrrole (py) as spacer and a pyrrole bearing a N-hydroxyphthalimidyl ester group on its 3-position (pyNHP), acting as agent linker for biomolecule immobilization, was optimized for an efficient immunosensor device. The ratio of py:pyNHP for copolymer formation was studied with respect to the antibody immobilization and antigen detection. SPR was employed to monitor in real time the electropolymerization process as well as the step-by-step construction of the biosensor. FT-IR demonstrates the chemical copolymer composition and the efficiency of the covalent attachment of biomolecules. The film morphology was analyzed by electron scanning microscopy (SEM).Results show that a well organized layer is obtained after Sc-Fv antibody immobilization thanks to the copolymer composition defined with optimized pyrrole and functionalized pyrrole leading to high and intense redox signal of the polypyrrole layer obtained by the DPV method. Detection of specific antigen was demonstrated by both SPR and DPV, and a low concentration of 1 pg mL⁻¹ was detected by measuring the variation of the redox signal of polypyrrole.     

Label-free DNA hybridization probe based on a conducting polymer

A new approach to the realization of the electrochemical DNA hybridization probe is described. It is based on the exchange of chloride ion between the polypyrrole layer and the buffer. The shape of the cyclic voltammogram is modulated by the negative charge density at this interface, resulting from the immobilized target DNA. The negative charge density increases when the complementary DNA hybridizes with the probe DNA. The hybridization event can be clearly seen in the cyclic voltammogram before and after the addition of the probe DNA. The immobilization is accomplished via the Mg2+ bridging complex between phosphonic acid groups of the poly[2,5-dithienyl-(N-3-phosphorylpropyl)pyrrole] grafted at the polypyrrole surface and the phosphate groups of the target DNA.     

Electrochemical biosensing of DNA hybridization by ferrocenyl groups functionalized polypyrrole

We have developed a new material based on polypyrrole functionalized with both ferrocenyl group and DNA probe. We have developed a precursor polymer based on a pyrrole 3-acetic acid and a pyrrole bearing ferrocenyl groups substituted by easy leaving group in which amino-labeled oligonocleotides probe were directly linked. The electrochemical response of the modified electrode was examined both in aqueous and organic media and shows high electroactivity in both media. A large modification of redox activity of ferrocenyl groups was obtained upon addition of ODN target to the electrolytic media, which is determined by amperometric methods. The detection limit of this electrochemical biosensor is about 10⁻¹⁴ mol without any signal processing.     

Facile preparation of carbon nanotube-conducting polymer network for sensitive electrochemical immunoassay of Hepatitis B surface antigen in serum

A novel electrochemical immunosensor built on three dimensional carbon nanotube-conducting polymer (CNT-CP) network is reported for detection of Hepatitis B surface antigen (HBsAg) in human serum. The CNT-CP network is prepared by drop-drying of CNT solution on glassy carbon electrode, followed by electrochemical polymerization of poly (pyrrole propionic acid) (pPPA) film to crosslink and stabilize the CNTs, wherein the CNTs form the backbone of the network, and offer great specific surface areas for antibody attachment, and confer good conductivity for electrochemical detection, while the conducting film integrates the carbon nanotubes into a stable network due to its self-limiting growth behavior and provides abundant carboxyl groups for covalent immobilization of probe proteins. As a unique matrix, the CNT-CP network enables sensitive electrochemical detection of HBsAg biomarker by using alkaline phosphatase (ALP)-conjugated secondary antibodies under sandwich format coupling with the ALP substrate solution, p-aminophenyl phosphate (PAPP), reaching a detection limit of 0.01ng/mL with a dynamic range of 5 orders of magnitude.     

电化学合成吡咯与己内酰胺导电共聚物

采用恒电位方法实现了吡咯与己内酰胺在导电玻璃电极上的直接电化学共聚,聚合反应在含有0.1mol/L吡咯和1.5 mol/L己内酰胺的硝基甲烷电解质溶液中进行,外加电位控制在1.2 V以上.聚合产物中聚吡咯与聚己内酰胺链段的组成可通过调节合成电位加以控制.共聚物的形貌、结构与性质采用扫描电子显微镜、热重分析、红外光谱等手...     

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。     

A nanocomposite consisting of plasma-polymerized propargylamine and graphene for use in DNA sensing

We report on a novel graphene-based nanoarchitecture modified with plasma-polymerized propargylamine (G-PpPG) and its application in electrochemical sensors for DNA. Films of G-PpPG were characterized by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. The presence of graphene enhances the electrochemical activity of the films, and the high density of amino groups (deposited at a low plasma input power) on their surface assists in the immobilization of probe DNA on the water-swollen polymeric network. By contrast, the degree of hybridization of the total complementary target DNA to the probe DNA remains unchanged when G-PpPG nanofilms prepared at higher input power. No substantial non-specific adsorption of totally mismatched target DNA on the polymer films is observed because of the complete coverage of the probe DNA. The detection limit for total complementary target DNA is approximately 1.84 nmol?·?L^?1. The dynamic range extends from 0.1 to 1,000 nmol?·?L^?1. The new nanocomposite may also be used to immobilize other probe DNA sequences, and this makes the approach potentially applicable to the detection of other oligomers. Figure

Preparing the DNA sensor made from the graphene-based nanoarchitecture modified by using PpPG (G-PpPG) includes the following processes: (a) Modifying the Au electrode with the graphene nanosheet, (b) depositing the PpPG film onto the Au electrode coated with graphene, (c) immobilizing the probe DNA onto the G-PpPG film, and (d) hybridizing the MM0 target with the G-PpPG film immobilized with P1