Masking method for improving selectivity of gold nanoclusters in fluorescence determination of mercury and copper ions.

In this report, we have developed a method that improved the selectivity of gold nanoclusters toward copper and mercury ions. Bovine serum albumin stabilized gold nanocluster responded to both these two ions through fluorescence quenching. EDTA and sodium borohydride were added respectively as the "masking" reagents, in which EDTA complexed with Cu²⁺, and borohydride reduced Hg²⁺ into Hg⁰. Both these reactions inhibited the ions' interaction with the nanocluster and eliminated related quenching effect, thus detection of the other ion was achieved. Good selectivity of the nanocluster over these two ions was obtained enabling sensitive detection even under their coexistence.