Fabrication of cefotaxime sodium-functionalized gold nanoclusters for the detection of copper ions in Chinese herbal medicines

Abstract

Antibiotic-based gold nanoclusters (AuNCs) are a good sensing platform for specific recognition; however, the related studies are few. Herein, a simple and facile strategy was proposed for the fabrication of bright blue fluorescent AuNCs through the degradation product (DCTX) of cefotaxime sodium that induced the reduction of HAuCl₄. Various analytical techniques were applied to characterize the prepared AuNCs@DCTX. AuNCs@DCTX exhibited a strong emission peak centered at 420 nm and a quantum yield of 11.8%. Furthermore, an aggregation-induced fluorescence quenching mode endowed the AuNCs@DCTX probe with good specificity and sensitivity for Cu²⁺ detection. The proposed probe had a linear range of 0.01–40 μM, a precision with a relative standard deviation of 1.2% (n = 8), and a detection limit of 8 nM (signal/noise = 3). Interestingly, the probe could be reused through switching the “off” and “on” states by the addition of Cu²⁺ and EDTA. The practicality of the sensing platform was investigated for the determination of Cu²⁺ in four Chinese herbal medicines (CHMs), and the results were in accordance with those obtained by the FAAS method. This study has provided an alternate way for the fabrication of thiolate-protected AuNCs for sensing applications.