Photocatalytic synthesis of BSA-Au nanoclusters with tunable fluorescence for highly selective detection of silver ion

Abstract

A new photocatalytic synthesis strategy for rapid preparation of BSA-Au nanoclusters (NCs) with tunable fluorescence was developed and used for the highly selective detection of silver ion. In this strategy, the silver ion was firstly photo-reduced to Ag NCs under UV light illumination. Then, the produced Ag NCs would further reduce HAuCl4 to Au NCs stabilized in BSA molecules. In this process, silver ion not only acted as a photocatalyst to accelerate the formation of fluorescent Au nanocluster but also as a regulator to tune the fluorescence emission color of the BSA-Au NCs from orange to red. The maximum emission peak of BSA-Au NCs fluorescence could be tuned from 570 to 620 nm in different experimental conditions. Furthermore, a fluorescence emission peak red-shifts of the as-prepared BSA-Au NCs could also be observed by subsequent adding of silver ion. Thus, a quantitative analytical method for silver ion detection could be established in the range from 5.0 to 60.0 μM with a detection limit (LOD) of 0.226 μM (3σ). The method had high selectivity that other common metal ions and small biological molecules did not have similar phenomena. It had great potential for applying for environmental water sample analysis.