Ag nanoclusters as nanozyme for detection of Hg2+ based on aggregation enhanced peroxidase-like activity

In this study, lysine protected silver nanoclusters (Lys-AgNCs) were prepared and the mimetic property was systematically investigated. The nanoclusters displayed oxidase-like and peroxidase-like activity for the catalytic oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB). Interestingly, the nanozyme property could be tuned by adjusting the pH or temperature. In the low pH (3.6–4.2), oxidase-like activity is predominant. In the high pH(4.2–5.4), peroxidase- like activity is the main activity. In the lower temperature (20–40 °C), oxidase-like activity is predominant. Importantly, the Lys-AgNCs showed stronger affinity for TMB. The activation energy of Lys-AgNCs was lower than bare Ag nanoclusters, indicating a faster reaction rate. In addition, a detection method for Hg 2+ was designed based on the aggregation enhanced peroxidase-like activity of lysine-Ag nanocluster with limit of detection (LOD) of 0.004 μM. The sensing assay exhibited excellent selectivity owing to the specific interaction between lysine and Hg 2+ and can be used in tap water with an acceptable recovery rate. Considering the cost-effective of this method, it is proposed to be used in practical application.