Marzouk Sayed A M, Ashraf S S, Tayyari Khawla A Al
Department of Chemistry, Faculty of Science, United Arab Emirates University, Al-Ain, PO Box 17551, United Arab Emirates.
Anal Chem. 2007 Feb 15;79(4):1668-74. doi: 10.1021/ac061886d.
This paper describes the first report on the development, characterization, and applications of a prototype amperometric biosensor for free sialic acid (SA). The sensor was constructed by the coimmobilization of two enzymes, i.e., N-acetylneuraminic acid aldolase and pyruvate oxidase, on a polyester microporous membrane, which was then mounted on top of a platinum disk electrode. The SA biosensor operation was based on the sequential action of the two enzymes to ultimately produce hydrogen peroxide, which was then detected by anodic amperometry at the platinum electrode. The surface of the platinum electrode was coated with an electropolymeric layer to enhance the biosensor selectivity in the presence of interfering oxidizable species. Optimization of the enzyme layer composition resulted in a fast and steady current response in phosphate buffer pH 7.2 at 37 degrees C. The limit of detection was 10 microM, and the response was linear to 3.5 mM (r = 0.9987). The prepared SA biosensors retained approximately 85% of their initial sensitivity after 8 days and showed excellent response reproducibility (CV = 2.3%). Utilization of a third enzyme, sialidase, expanded the scope of the present SA biosensor to determine bound sialic acid as well. The merits of the described biosensor allowed its successful application in determining SA in biological and pharmaceutical samples. The obtained results indicated that the presented SA biosensor should be a useful bioanalytical tool in several biological and clinical applications such as screening of SA as a nonspecific tumor marker as well as monitoring of tumor therapy.
本文介绍了首个关于用于游离唾液酸（SA）的安培型生物传感器原型的开发、表征及应用的报告。该传感器通过将两种酶，即N - 乙酰神经氨酸醛缩酶和丙酮酸氧化酶共固定在聚酯微孔膜上构建而成，然后将其安装在铂盘电极顶部。SA生物传感器的运作基于这两种酶的顺序作用，最终产生过氧化氢，然后通过铂电极上的阳极电流分析法进行检测。铂电极表面涂有一层电聚合层，以增强生物传感器在存在干扰性可氧化物质时的选择性。酶层组成的优化使得在37摄氏度的pH 7.2磷酸盐缓冲液中能产生快速且稳定的电流响应。检测限为10微摩尔，响应在3.5毫摩尔范围内呈线性（r = 0.9987）。制备的SA生物传感器在8天后保留了约85%的初始灵敏度，并显示出出色的响应重现性（CV = 2.3%）。使用第三种酶唾液酸酶，扩大了当前SA生物传感器测定结合唾液酸的范围。所描述的生物传感器的优点使其能够成功应用于生物和药物样品中SA的测定。获得的结果表明，所展示的SA生物传感器在多种生物和临床应用中应是一种有用的生物分析工具，例如将SA作为非特异性肿瘤标志物进行筛查以及监测肿瘤治疗。
