A sensitive DNA biosensor based on a facile sulfamide coupling reaction for capture probe immobilization

A novel DNA biosensor was fabricated through a facile sulfamide coupling reaction. First, the versatile sulfonic dye molecule of 1-amino-2-naphthol-4-sulfonate (AN-SO₃⁻) was electrodeposited on the surface of a glassy carbon electrode (GCE) to form a steady and ordered AN-SO₃⁻ layer. Then the amino-terminated capture probe was covalently grafted to the surface of SO₃⁻-AN deposited GCE through the sulfamide coupling reaction between the amino groups in the probe DNA and the sulfonic groups in the AN-SO₃⁻. The step-by-step modification process was characterized by electrochemistry and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Using Ru(NH₃)₆³⁺ as probe, the probe density and the hybridization efficiency of the biosensor were determined to be 3.18 × 10¹³ strands cm⁻² and 86.5%, respectively. The hybridization performance of the biosensor was examined by differential pulse voltammetry using Co(phen)₃^3+/2+ (phen = 1,10-phenanthroline) as the indicator. The selectivity experiments showed that the biosensor presented distinguishable response after hybridization with the three-base mismatched, non-complementary and complementary sequences. Under the optimal conditions, the oxidation peak currents of Co(phen)₃^3+/2+ increased linearly with the logarithm values of the concentration of the complementary sequences in the range from 1.0 × 10⁻¹³ M to 1.0 × 10⁻⁸ M with a regression coefficient of 0.9961. The detection limit was estimated to be 7.2 × 10⁻¹⁴ M based on 3σ.     

Electrochemical DNA Biosensor Based on Partially Reduced Graphene Oxide Modified Carbon Ionic Liquid Electrode for the Detection of Transgenic Soybean A2704‐12 Gene Sequence

In this work a partially reduced graphene oxide (p‐RGO) modified carbon ionic liquid electrode (CILE) was prepared as the platform to fabricate an electrochemical DNA sensor, which was used for the sensitive detection of target ssDNA sequence related to transgenic soybean A2704‐12 sequence. The CILE was fabricated by using 1‐butylpyridinium hexafluorophosphate as the binder and then p‐RGO was deposited on the surface of CILE by controlling the electroreduction conditions. NH₂ modified ssDNA probe sequences were immobilized on the electrode surface via covalent bonds between the unreduced oxygen groups on the p‐RGO surface and the amine group at the 5′‐end of ssDNA, which was denoted as ssDNA/p‐RGO/CILE and further used to hybridize with the target ssDNA sequence. Methylene blue (MB) was used as electrochemical indicator to monitor the DNA hybridization. The reduction peak current of MB after hybridization was proportional to the concentration of target A2704‐12 ssDNA sequences in the range from 1.0×10^?12 to 1.0×10^?6 mol/L with a detection limit of 2.9×10^?13 mol/L (3σ). The electrochemical DNA biosensor was further used for the detection of PCR products of transgenic soybean with satisfactory results.     

Functionalized polypyrrole nanotube arrays as electrochemical biosensor for the determination of copper ions

A novel electrochemical biosensor based on functionalized polypyrrole (PPy) nanotube arrays modified with a tripeptide (Gly-Gly-His) proved to be highly effective for electrochemical analysis of copper ions (Cu²⁺). The vertically oriented PPy nanotube arrays were electropolymerized by using modified zinc oxide (ZnO) nanowire arrays as templates which were electrodeposited on indium–tin oxide (ITO) coated glass substrates. The electrodes were functionalized by appending pyrrole-α-carboxylic acid onto the surface of polypyrrole nanotube arrays by electrochemical polymerization. The carboxylic groups of the polymer were covalently coupled with the amine groups of the tripeptide, and its structural features were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy. The tripeptide modified PPy nanotube arrays electrode was used for the electrochemical analysis of various trace copper ions by square wave voltammetry. The electrode was found to be highly sensitive and selective to Cu²⁺ in the range of 0.1–30 μM. Furthermore, the developed biosensor exhibited a high stability and reproducibility, despite the repeated use of the biosensor electrode.     

Study of Inhibition,Reactivation and Aging Processes of Pesticides Using Graphene Nanosheets/Gold Nanoparticles‐Based Acetylcholinesterase Biosensor

Organophosphate (OP) and carbamate pesticides exert their toxicity via attacking the hydroxyl moiety of serine in the ‘active site’ of acetylcholinesterase (AChE). In this paper we developed a stable AChE biosensor based on self‐assembling AChE to graphene nanosheet (GN)‐gold nanoparticles (AuNPs) nanocomposite electrode for investigation of inhibition, reactivation and aging processes of different pesticides. It is confirmed that pesticides can inhibit AChE in a short time. OPs poisoning is treatable with oximes while carbarmates exposure is insensitive to oximes. The proposed electrochemical approach thus provides a new simple tool for comparison of pesticide sensitivity and guide of therapeutic intervention.     

Ferrocene and Ferricenium Ion as Versatile Photometric Titrants of H2O2 and D-Glucose in the Presence of Peroxidase and Glucose Oxidase. A Ferrocene-Peroxidase Stairway #

Abstract

Hydrogen peroxide can routinely be determined in the presence of ferrocene (FcH) and horseradish peroxidase by monitoring at 617 nm the enzymatically produced ferricenium dye. In contrast, D-glucose can be assayed by following the fading of the ferricenium dye FcH⁺PF₆ ^? in the presence of glucose oxidase. The change in absorbance in both cases corresponds to the amount of analyte. viz. H₂O₂ or D-glucose, in solution. The routine is very simple, invariant to the concentrations of both ferrocenes/ferricenium salt and enzyme and allows numerous “one pot” measuremeats with the detection limit of 10^?4 M for both the analytes. It takes 2–4 and 5–10 min to accomplish one analysis of H₂O₂ and D-glucose in the presence of peroxidase and glucose oxidase, respectively.

     

光纤生物传感器用于核酸的特异性检测

为了利用光纤传感器实现对细菌核酸分子的特异性和相对快速检测，我们使用直径1mm的石英光纤和635nm激光二极管，利用倏逝波原理制作了光纤生物传感器。光纤经过处理后产生醛基化基团，然后与核酸分子进行共价结合。通过3个实验来验证传感器的特异性和灵敏度。蒌光素溶液直接检测，使用互补模式寡核苷酸分子（25mer)进行核酸杂交模式实验和设计嗜肺军团菌一段特异性探针一 光标记嗜肺军团菌染色体DNA杂交。结果表明：光纤检测荧光素的灵敏度可达0.01mmol/L，而生物芯片扫描仪最低可检测到1nmol/L的荧光素；模式寡 核苷酸杂交表明：光纤传感器可以特异地检出目的核酸分子，灵敏度可达纳克级水平；染色体杂交结果显示在正常检测浓度下，光纤检测军团菌之信噪比达到了6：1，同时具有较好的特异性。检测时间约需要3－4h。我们构建的光纤生物传感器可以用于核酸分子的特异性检测，并且具有较好的灵敏度，对光纤表面修饰、样品处理和杂交过程的优化可望使之应用于实际标本的检测。     

电化学DNA传感器的研制及其医学应用

对近几年发展起来的电化学DNA传感器的研究工作进行了讨沦,详细论述了该类传感器的工作原理、探针固定化技术、杂交指示剂的类型以及在基因诊断、药物分析等方面的医学应用,并展望了应用前景和发展方向。     

普鲁士蓝修饰电极结合硅溶胶-凝胶技术制备高灵敏葡萄糖传感器

基于普鲁士蓝修饰玻碳电极结合二氧化硅溶胶 凝胶固定化酶技术构造具有“三明治”式结构的酶电极。考察了酶电极对葡萄糖的电化学响应以及操作条件。结果表明 :所制备的传感器在pH 6 .5 ,电位为- 0 .0 5V条件下对葡萄糖在 0～ 5mmol/L呈线性响应 ,响应时间为 12s ,检出限为 0 .0 2mmol/L ,灵敏度高达1 182 μA/ (mmol·L-1)。传感器的稳定性好 ,4 5d其响应值仍保持 90 %。     

硅溶胶-凝胶包埋纳米金和酶的葡萄糖生物传感器

采用溶胶-凝胶技术将金纳米粒子和葡萄糖氧化酶一次性固定于硅溶胶-凝胶的网络结构中,制备了葡萄糖生物电化学传感器并优化了传感器的制备条件。酶电极对葡萄糖具有良好的电化学响应,葡萄糖浓度在0.02~2.0 mmol/L范围内和催化电流呈线性关系,检出限为0.005 mmol/L。酶电极在4 ℃下贮存100 d后对葡萄糖的响应仅下降8%。该酶电极灵敏度高、响应快、稳定性好。     

碳纳米管在电化学和光化学纳米生物传感器中的应用

碳纳米管(CNTs)因具有独特的物理化学及电化学性质,如较大的比表面积、较强的电子转移能力和良好的吸附性能等而引起人们的广泛关注.碳纳米管可以通过物理吸附、静电或疏水作用等非共价结合方式或共价连接方式固定生物大分子(如蛋白质、DNA、抗体等),有效地促进生物大分子与电极间直接、快速的电子转移,可应用于多种电化学生物传感器中.碳纳米管本身在近红外光区具有独特的荧光和拉曼光谱,可以利用多种光谱手段对多种生物分子实现定量检测,因此近年来碳纳米管在光化学生物传感器中的应用也逐渐受到了研究者的重视.本文对碳纳米管在电化学和光化学生物传感器中的应用进行了简要综述和展望.