Bai Yu-Hui, Xu Jing-Juan, Chen Hong-Yuan
Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
Biosens Bioelectron. 2009 Jun 15;24(10):2985-90. doi: 10.1016/j.bios.2009.03.008. Epub 2009 Mar 17.
We report a simple approach for the selectively electrochemical sensing of cysteine (CySH) using beta-MnO(2) nanowires modified glassy carbon (GC) electrode via a direct and facile electrochemical co-deposition process with chitosan hydrogel. The electrode showed excellent electrocatalytic effect toward cysteine oxidation. A possible reaction mechanism related to the formation of surface complexes was proposed: the -SH group is the reacting group in the reaction between cysteine and MnO(2), while the -NH(2) group acts as an anchor to stabilize the surface complexes. The electrocatalytic behavior is further developed as a sensitive detection scheme for cysteine by amperometric measurement, which shows a large determination range of 0.5-630 microM and a low detection limit of 70 nM. Other nineteen amino acids in a 20-fold concentration do not interfere in the detection of cysteine. Furthermore, other biological species containing -SH group or S-S bonds, such as glutathione, cystine, and bovine serum albumin (BSA), show no interferences because of steric hindrance and inactive S-S bonds.
我们报道了一种简单的方法，通过壳聚糖水凝胶的直接且简便的电化学共沉积过程，利用β-MnO₂纳米线修饰玻碳（GC）电极对胱氨酸（CySH）进行选择性电化学传感。该电极对胱氨酸氧化显示出优异的电催化效果。提出了一种与表面络合物形成相关的可能反应机理：-SH基团是胱氨酸与MnO₂反应中的反应基团，而-NH₂基团作为锚定基团来稳定表面络合物。通过安培测量进一步将电催化行为发展为一种用于胱氨酸的灵敏检测方案，其显示出0.5 - 630 μM的大测定范围和70 nM的低检测限。浓度为20倍的其他19种氨基酸不干扰胱氨酸的检测。此外，其他含有-SH基团或S-S键的生物物种，如谷胱甘肽、胱氨酸和牛血清白蛋白（BSA），由于空间位阻和无活性的S-S键而不产生干扰。
