L-Proline-methyl ester derivative-modulated synthesis of gold nanoclusters with promoted peroxidase-mimic activity for monitoring of ofloxacin.

Abstract

Gold nanoclusters (AuNCs), stabilized and functionalized by organic ligands, have served as new generation materials for applications in nanocatalysis. To further expand and regulate the catalytic function of AuNCs, the exploration of surface interactions and modulated-ligand properties is highly desirable. This study presents the fabrication of four kinds of AuNCs using L-proline-methyl ester derivatives as ligands. Among these AuNCs nanocatalysts, the highest peroxidase-mimic catalytic activity in an oxidation reaction of 3,3',5,5'-tetramethylbenzidine (TMB) with hydrogen peroxide is observed when using L-proline-methyl ester capped AuNCs (POMe@AuNCs) as the nanozymes. Notably, the addition of ofloxacin in the oxidation system yields more reactive oxygen species, resulting in a significant increase in catalytic capability. A colourimetric sensing strategy is developed for the highly selective and sensitive measurement of ofloxacin. The UV-vis absorption of oxTMB at 650 nm exhibits a good linear relationship with the ofloxacin amount, ranging from 0.6 μM to 12.0 μM (R2 = 0.998), and the detection limit is 0.2 μM. The protocol further displays its potential application in monitoring rat serum ofloxacin variation in a drug-metabolic-process. This study not only demonstrates a unique strategy for the ligand-modulated synthesis of AuNCs, but also guides future detection of drugs that can enhance the catalytic capability of AuNCs.