Mbouguen Justin Kemmegne, Ngameni Emmanuel, Walcarius Alain
Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, Unité Mixte de Recherche UMR 7564, CNRS, Nancy-Université, 405, rue de Vandoeuvre, F-54600 Villers-les-Nancy, France.
Biosens Bioelectron. 2007 Sep 30;23(2):269-75. doi: 10.1016/j.bios.2007.04.008. Epub 2007 Apr 22.
Naturally occurring Cameroonian smectite clay has been grafted with trimethylpropylammonium (TMPA) groups and the resulting organoclay has been deposited onto a glassy carbon electrode surface as a suitable immobilization matrix for polyphenol oxidase (PPO). High sensitivity of the electrochemical device to catechol biosensing can be achieved when the enzyme was impregnated within the organoclay film subsequent to its deposition due to favorable electrostatic interaction between PPO and the TMPA-clay layer. The bioelectrode preparation method was also compatible with the use of a mediator (i.e., ferrocene) and the best performance was obtained with a three-layer configuration made of glassy carbon coated with a first layer of ferrocene (Fc), which was then covered with the PPO-impregnated TMPA-clay layer, and finally overcoated with an enzyme-free TMPA-clay film acting as a protecting overlayer to avoid leaching of the biomolecule in solution. The electrochemical behavior of the modified film electrodes was first characterized by cyclic voltammetry and, then, they were evaluated for the amperometric biosensing of the model analyte catechol in batch conditions and in flow injection analysis. Various experimental parameters likely to influence the biosensor response have been investigated, including the electrode preparation mode (composition configuration, thickness), the usefulness of a mediator, the operating potential and pH of the medium, as well as the advantageous features of the TMPA-clay in comparison to related film electrodes based on non-functionalized clays. The organoclay was found to provide a favorable environment to enzyme activity and the multilayer configuration of the film electrode to provide a biosensor with good characteristics, such as an extended linear range for catechol detection (2 x 10(-8) to 1.2 x 10(-5)M) and a detection limit in the nanomolar range (9 x 10(-9)M).
天然存在的喀麦隆蒙脱石粘土已接枝有三甲基丙基铵（TMPA）基团，所得有机粘土已沉积在玻碳电极表面上，作为多酚氧化酶（PPO）合适的固定基质。当酶在沉积后浸渍在有机粘土膜中时，由于PPO与TMPA-粘土层之间有利的静电相互作用，电化学装置对儿茶酚生物传感可实现高灵敏度。生物电极制备方法也与使用介体（即二茂铁）兼容，并且由涂有第一层二茂铁（Fc）的玻碳制成的三层配置获得了最佳性能，然后用浸渍有PPO的TMPA-粘土层覆盖，最后用无酶的TMPA-粘土膜作为保护覆盖层进行覆盖，以避免生物分子在溶液中浸出。首先通过循环伏安法表征修饰膜电极的电化学行为，然后在批量条件下和流动注射分析中评估它们对模型分析物儿茶酚的安培生物传感。研究了各种可能影响生物传感器响应的实验参数，包括电极制备模式（组成配置、厚度）、介体的有用性、介质的操作电位和pH值，以及与基于未功能化粘土的相关膜电极相比，TMPA-粘土的有利特征。发现有机粘土为酶活性提供了有利环境，并且膜电极的多层配置为生物传感器提供了良好的特性，例如儿茶酚检测的扩展线性范围（2×10（-8）至1.2×10（-5）M）和纳摩尔范围内的检测限（9×10（-9）M）。
