Electrochemical Biosensors for Cancer Biomarker Detection

Cancer is still one of the leading causes of death in the world. There are over 200 types of cancers currently known according to the National Cancer Institute. However, early diagnosis continues to be an important integral part of cancer treatment even though many advances in therapeutics have been made in the past decade. Quick diagnosis and early prevention are critical for the control of the disease status. Biomarkers are commonly indicative of a particular disease process and the cancer biomarkers are also widely used in oncology to help detecting the presence of various carcinomas. The detection of cancer biomarkers plays an important role in clinical diagnoses and evaluation of treatment for patients. Many immunoassay methods are developed for detection of cancer biomarkers. As the detection devices are normally viewed with high sensitivity, simple preparation and rapid response, electrochemical biosensors are increasingly used for the detection of cancer markers. This review describes the status, the latest research and trends of electrochemical sensors in the quantitation of cancer markers in recent years. In particular, the strategy to improve the sensitivities of the electrochemical biosensors by the aid of enzymatic amplification, nanoparticle amplification, ultilization of magnetic microspheres etc. is described herein. At last, we discuss some special features and limitations associated with the described systems that summarize the application and the development prospects of electrochemical immunoassay technology.     

Electrochemical Biosensors Based on Layer‐by‐Layer Assemblies

Layer‐by‐layer (LBL) assemblies, which have undergone great progress in the past decades, have been used widely in the construction of electrochemical biosensors. The LBL assemblies provide a strategy to rationally design the properties of immobilized films and enhance the performance of biosensors. The following review focuses on the application of LBL assembly technique on electrochemical enzyme biosensors, immunosensors and DNA sensors.     

Targeting Chemical and Biological Warfare Agents at the Molecular Level

After the September 11 tragedies of 2001, scientists and law‐enforcement agencies have shown increasing concern that terrorist organizations and their “rogue” foreign government‐backers may resort to the use of chemical and/or biological agents against U.S. military or civilian targets. In addition to the right mix of policies, including security measures, intelligence gathering and training for medical personnel on how to recognize symptoms of biochemical warfare agents, the major success in combating terrorism lies in how best to respond to an attack using reliable analytical sensors. The public and regulatory agencies expect sensing methodologies and devices for homeland security to be very reliable. Quality data can only be generated by using analytical sensors that are validated and proven to be under strict design criteria, development and manufacturing controls. Electrochemical devices are ideally suited for obtaining the desired analytical information in a faster, simpler, and cheaper manner compared to traditional (lab‐based) assays and hence for meeting the requirements of decentralized biodefense applications. This articler presents a review of the major trends in monitoring technologies for chemical and biological warfare (CBW) agents. It focuses on research and development of sensors (particularly electrochemical ones), discusses how advances in molecular recognition might be used to design new multimission networked sensors (MULNETS) for homeland security. Decision flow‐charts for choosing particular analytical techniques for CBW agents are presented. Finally, the paths to designing sensors to meet the needs of today's measurement criteria are analyzed.     

毒剂的生化分析技术

本文论述了酶法分析、核酸探针、免疫分析法特别是生物传感器在毒剂检测中的应用，提出了毒剂生化分析的发展方向。     

脱氧核糖核酸电化学传感器的原理及其应用

对电化学DNA传感器的组成及其在DNA损伤研究、环境污染监控、病原基因检测、基因疾病诊断和药物机理分析等方面的进行了总结，并对其发展趋势进行了评述。     

Application of Impedimetric and Voltammetric Genosensor for Detection of a Biological Warfare: Anthrax

A strategy for the detection of anthrax, which is a potential biological weapon by using an electrochemical genosensing technology, is investigated. An alkanathiol‐linked or unlabeled capture probe related to B. anthracis is immobilized onto gold or graphite electrode surface. A 101‐mer anthrax target is used for hybridization. The extent of hybridization between probe and target sequences is determined by using differential pulse voltammetry (DPV) and electrochemical impedance spectrometry (EIS). EIS analysis are based on electron transfer resistance (R_ct) in the presence of [Fe(CN)₆]^3?/4? and DPV measurements are based on transduction of both guanine oxidation and Meldola's blue (MDB) reduction signal as hybridization indicator. The response of the probe‐modified electrodes which was interacted with a noncomplementary sequence was the same as the responses of probe‐modified surface and proved the specifity of the hybridization with the target. According to these results the developed genosensors based on EIS and DPV techniques can be employed for rapid and selective detection of B. anthracis.     

基于核酸适体的电化学生物传感器*

核酸适体是一类体外筛选的、可与目标分子高效、高特异亲合的RNA或DNA寡核苷酸片段,与常规识别分子（如抗体等）相比,核酸适体作为一类新型识别分子具有明显特色和优势,已被广泛应用于生物传感等分子识别和应用研究领域。本文就基于核酸适体的电化学生物传感器（标记型和非标记型）的近期进展作简要评述,包括适体简介、标记型（“信号衰减”型、“信号增强”型、酶标记型和纳米粒子标记型）和非标记型电化学适体生物传感器等内容。     

Application of Polyfolates in the Development of Electrochemical Glucose Biosensors

Folic acid was polymerised electrochemically at a glassy carbon electrode surface from 0.1 mol L^?1 phosphate buffer saline solution, pH 5.0, containing 0.1 mmol L^?1 monomer. The obtained thin film was porous with a pore size of 50–60 nm. Since its electrochemical stability was rather short, the polyfolate film was covered with a graphene‐chitosan composite layer which increased its stability significantly. The best strategy to immobilise the enzyme was crosslinking with glutaraldehyde. The lifetime of this glucose biosensor in use was at least 12 days, on‐shelf life time was at least 30 days. The linear range was up to 1 mmol L^?1 and the LOD was 0.6 µmol L^?1. The first polyfolate‐based biosensor was applied to analysis of natural samples.     

电化学葡萄糖传感器

作为电化学生物传感器中最重要的研究内容之一,葡萄糖生物传感器在数十年的发展中取得了巨大进展。本文综述了近年来利用纳米技术设计的新型电化学葡萄糖传感器的主要研究进展,并从纳米材料维度分类进行了讨论。其中,零维纳米材料主要讨论了包括金纳米颗粒、银纳米颗粒以及铜、铂等金属纳米颗粒材料; 一维纳米材料主要讨论了通过模板法制备的金属或金属氧化物纳米线以及单臂或者多壁纳米管材料; 二维纳米材料主要总结了以碳为基础的石墨烯材料和一些片状的金属材料。纳米材料对电化学葡萄糖传感器的影响主要集中在生物相容性、增强检测灵敏度、酶的固定等方面。此外,本文也对电化学葡萄糖传感器的今后发展做了展望。     

化学毒剂探测技术发展现状

化学毒剂(CWAs)作为一种大规模杀伤性武器,具有杀伤力强、影响范围广、防护困难、易于制作施放等特征,从诞生之初即常被用于战争冲突,在现代非对称战争、恐怖袭击中也造成了巨大威胁.因此如何及时地探测化学毒剂成为世界各国国土安全的重点研究方向.该文聚焦于化学毒剂现有主流及具有潜力的各类探测技术,对各种检测技术的基本原理及其...     

Stilbene-Based Fluorescent Sensor for Detection of Organophosphorus Warfare Nerve Agents

In this paper, we report the synthesis of stilbene-based fluorophore, 3,4-dihydroxy-4′-aminostilbene (DHAS) for the detection of chemical warfare agents such as organophosphorus nerve gases. DHAS was characterized by various spectroscopic methods and grafted on to electrospun nanofibers. The interaction of DHAS with nerve agents simulant, diethyl chlorophosphate (DCP) was investigated in solution and vapor phase by fluorescence spectroscopy.     

Electrochemical Biosensors Based on Enzymatic Reactor of Silver Solid Amalgam Powder for Measurements in Flow Systems

An enzymatic reactor based on silver solid amalgam powder was suggested as the main part of biosensors in flow systems for the first time. Biosensors were tested with following enzymes: ascorbate oxidase, glucose oxidase, catalase, tyrosinase and laccase. The current response of each biosensor was optimized with respect to the detection potential, flow rate, the injection and reactor volume. Relative standard deviation for detection with the studied enzymes was found to be in the range of 0.81–2.1 %. The biosensor with the ascorbate oxidase reactor was used for determination of ascorbic acid in the vitamin tablets Celaskon.     

纳米电化学生物传感器

纳米电化学生物传感器是将纳米材料作为一种新型的生物传感介质,与特异性分子识别物质如酶、抗原/抗体、DNA等相结合,并以电化学信号为检测信号的分析器件。本文简要介绍了生物传感器的分类和纳米材料在电化学生物传感器中的应用及其优势,综述了近年来各类纳米电化学生物传感器在生物检测方面的研究进展,包括纳米颗粒生物传感器,纳米管、纳米棒、纳米纤维与纳米线生物传感器,以及纳米片与纳米阵列生物传感器等。     

电化学DNA生物传感器研究的应用进展*

电化学DNA生物传感器因快速、灵敏、低耗和易于操作等优点在基因序列测定中受到了广泛的关注,已逐渐成为分子生物学和生物技术研究的重要领域。具有电活性的小分子和纳米材料因它们独特的性质,已被应用到电化学DNA生物传感器中。本文介绍了电化学DNA生物传感器的基本概念和分类,综述了近年来电活性小分子和纳米材料在电化学DNA生物传感器中的应用进展,并对此领域的未来发展做了展望。     

Electrochemical Biosensors for Cancer Biomarkers Detection: Recent Advances and Challenges

Biomarkers are described as characteristics that provide information about biological conditions whether normal or pathological. Detection of biomarkers at the earliest stage of the cancer is of utmost importance for clinical diagnosis. Electrochemical biosensors allow detecting the low levels of specific analytes in blood, urine or saliva and providing a sensitive approach for direct measurement for cancer biomarker detection. Moreover, the integration of electrochemical devices with nanomaterials, such as carbon nanotubes, gold and magnetic particles offer amplification and multiplexing capabilities for simultaneous measurements of cancer biomarkers very sensitively. This review summarizes the recent developments of electrochemical biosensors systems for the detection of cancer biomarkers with emphasis on voltammetric, amperometric and impedimetric biosensors. A special attention is paid to aptamers and miRNAs that are very promising for the ultra‐sensitive and specific cancer biomarker detection.     

In Vivo Electrochemical Biosensors for Reactive Oxygen Species Detection: A Mini-Review

Due to the significance of reactive oxygen species (ROS) in numerous physiological processes including pathogen response, apoptosis, and induction of defense genes, various methods have been developed for their quantitative analysis. However, the conventional methods using exogenous tracers lack the capability to conduct real-time in vivo measurements. The electrochemical biosensors have shown their potentials for in vivo applications with the rapid and reagentless detection processes. In this article, electrochemical biosensors that are capable of making in vivo ROS detections are reviewed. The different configurations of these biosensors with corresponding strategies to enhance sensitivity and selectivity are discussed in detail. With further studies to promote the biosensor performance, these devices promise to provide more facile ways for ROS research in life sciences.     

PAMAM Dendrimers‐Based DNA Biosensors for Electrochemical Detection of DNA Hybridization

Gold electrodes were modified with submonolayers of mercaptoacetic acid (RSH) and further reacted with poly(amidoamine) (PAMAM) dendrimers (generation 4.0) to obtain thin films, on which DNA probe was later immobilized to afford a stable recognition layers. The characterization of the PAMAM/RSH‐modified electrode was investigated by cyclic voltammetry (CV) and electrochemical impedance measurement. Differential pulse voltammogram (DPV) measurement was used to monitor DNA hybridization with daunomycin (DNR) as indicator. Experiments carried out with these novel materials not only showed an improved DNA attachment quantity on the dendrimers‐modified electrodes compared to DNA sensors with oligonucleotides directly immobilized on Au electrodes, but also exhibited a high selectivity, sensitivity and stability for the measurement of DNA hybridization.     

Recent Progress on Graphene‐based Electrochemical Biosensors

The detailed records and conclusions on the important advancements in graphene‐based electrochemical biosensors have been reviewed. Due to their outstanding properties, graphene‐based materials have been widely studied for the accurate electrochemical detection of many biomolecules, which is extremely vital to the development of biomedical instruments, clinical diagnosis, and disease treatment. This review discusses the graphene research for the effective immobilization of enzymes, including glucose oxidase, horseradish peroxidase, and hemoglobin, etc., and the accurate detection of biomolecules, including glucose, hydrogen peroxide, dopamine, ascorbic acid, uric acid, nicotinamide adenine dinucleotide, DNA, RNA, and carcinoembryonic antigen, etc. In most of the cases, the graphene‐based biosensors exhibited remarkable performance with high sensitivities, wide linear detection ranges, low detection limits, and long‐term stabilities.     

硅纳米线阵列电极作为细胞色素c传感器的研究

利用化学刻蚀法由p型硅片制备了硅纳米线阵列,经过表面去氧化层处理后,制备了检测蛋白质细胞色素c的电化学传感器.实验表明,硅纳米线阵列电极对细胞色素c有良好的电化学响应,并且在低浓度条件下具备线性响应的特点.根据与未经表面处理的硅纳米线阵列电极的实验结果相对比,提出了细胞色素c所具备的羧基末端与硅纳米线阵列电极表面的Si-H相互作用从而改善传感性能的检测机理.