Novel dual ligand co-functionalized fluorescent gold nanoclusters as a versatile probe for sensitive analysis of Hg(2+) and oxytetracycline.

Abstract

In this work, we present a direct one-step strategy for rapidly preparing dual ligand co-functionalized fluorescent Au nanoclusters (NCs) by using threonine (Thr) and 11-mercaptoundecanoic acid (MUA) as assorted reductants and capping agents in aqueous solution at room temperature. Fluorescence spectra, high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and infrared (IR) spectroscopy were performed to demonstrate the optical properties and chemical composition of the as-prepared AuNCs. They possess many attractive features such as near-infrared emission (λem = 606nm), a large Stoke's shift (>300nm), high colloidal stability (pH, temperature, salt, and time stability), and water dispersibility. Subsequently, the as-prepared AuNCs were used as a versatile probe for "turn off" sensing of Hg(2+) based on aggregation-induced fluorescence quenching and for "turn-on" sensing of oxytetracycline (OTC). This assay provided good linearity ranging from 37.5 to 3750nM for Hg(2+) and from 0.375 to 12.5μM for OTC, with detection limits of 8.6nM and 0.15μM, respectively. Moreover, the practical application of this assay was further validated by detecting OTC in human serum samples.