Biomimetic construction of protein-conjugated gold clusters for detecting Hg2+

Abstract

Mercury ion (Hg2+) pollution has deleterious effects on the environment and human health. Herein, through one-step biomimetic mineralization of metal salt with a natural protein, we develop an optical sensor system for Hg2+ detection with high selectivity and sensitivity. Glucose oxidase (GOD) serves as both a template and reducing agent to achieve the in situ biomineralization of Au (III), producing stable fluorescent GOD-conjugated gold clusters (GOD-AuCs) with a high yield. The probe above with a uniform core size of around 2.5nm, has an obvious maximum fluorescence emission peak at 686nm. GOD-AuCs exhibit good selectivity to Hg2+, in comparison to other metal ions including K+, Na+, Ca2+, Mg2+, Zn2+ and Cu2+. The reason might be that the existence of a small amount of Au+ (21%) on the surface of the cluster, permits strong metallophilic interaction between GOD-AuCs and Hg2+. It results in the instantaneous and remarkable fluorescence quench. Moreover, the intensity of fluorescence quench is found to be linearly depended on the concentration of Hg2+, with a detection limit of 7.5μM. These favorable findings promise GOD-AuCs have a good potential in monitoring environmental Hg2+.