Naked-eye colorimetric analysis of Hg2+ with bi-color CdTe quantum dots multilayer films

A novel direct quantificational method through naked-eye colorimetric analysis of Hg2+ was constructed based on different degree of the fluorescence quenching of bi-color quantum dots (QDs) multilayer films (2-QDMF). The functional multilayer films were assembled by layer-by-layer (LBL) deposition of oppositely charged CdTe QDs and poly(dimethyldiallylemmonium chloride) (PDDA). Then the outermost layer of 2-QDMF was cross-linked to bovine serum albumin (BSA), polyethylene glycol (PEG) or glutathione (GSH). It was found that when BSA modified quartz slides were immersed into solutions containing Hg2+ and Cu2+ respectively, the 2-QDMF can be quenched by Hg2+, but not by Cu2+. Under the optimization conditions, the quenched photoluminescence (PL) intensities of multilayer films were almost linearly proportional to the concentration of Hg2+ in the range of 1.0 × 10−8 to 1.0 × 10−6 mol L−1 and the detection limit was 4.5 × 10−9 mol L−1. The proposed method is intuitional and convenient, which can be applied to the determination of trace Hg2+ in the artificial water sample with satisfactory results.