功能化纳米金增强的谷胱苷肽电化学检测和巯基识别

Functional Gold Nanoparticles-enhanced Electrochemical Detection of Glutathione Cross-linking Reaction and Sulfhydryl-specific Identification

以冠有大量二茂铁的纳米金微粒/抗生蛋白链菌素结合物为标记物,将其标记于生物素修饰的巯基识别试剂上,制成了具有电化学活性和纳米金放大作用的传感器.首先将双官能团的羟基琥珀酰亚胺酯自组装于电极表面上,借助两步交联反应固定含巯基的蛋白质,并且引入巯基识别试剂标记生物素的马来酰亚胺,随后利用生物素与链霉抗生物素之间的特异性吸附作用,引入功能化的纳米金.采用伏安法测定修饰在纳米金上的二茂铁,可识别和测定表面固定的蛋白质,还原型谷胱苷肽在5μmol/L～0.1mmol/L浓度范围内存在线性关系,检测限可达到1nmol/L.

An electrochemical detection method for the cross-linking reaction and sulfhydryl-specific ~identification of GSH using ferrocene-capped gold nanoparticles/streptavidin conjugates was developed in this paper. Disulfide C11-NHS organic molecules were covalently immobilized on a gold electrode via {Au-S} bonds(-S-S-is reduced to-SH easily in ethyl acetate solution) and formed compact self-assembled monolayers(SAMs). Then GSH is attached to C11-NHS through the amide formation and continues to cross-link Biotin-maleimide by forming a stable thioether bond between the sulfhydryl group and double bond of the maleimide group. Finally, the ferrocene-capped functional gold nanoparticles were introduced via strong interaction effect between biotin and streptavidin. The binding events were monitored by electrochemical signal of ferrocene covering on the gold nanoparticles by voltammetry. The signal differences permit to distinguish whether there is free sulfhydryl groups in the surface-bound biomolecules. The ferrocene signal is enlarged greatly because of quantities of ferrocene moieties covering on the nanogold surface. The well-defined redox peaks attribute to that of ferrocene immobilized through the cross-linking reaction between sulfhydryl groups in GSH and maleimide groups in Biotin-maleimide. The sensitivity of this electrochemical biosensor was detected and an excellent linearity of 5 μmol/L-0.1 mmol/L for GSH concentration with the oxidation current and a detection limit of 1 mmol/L were also achieved.