A phosphorescence resonance energy transfer-based "off-on" long afterglow aptasensor for cadmium detection in food samples

Cadmium contamination is a severe food safety risk for human health. Herein, a long afterglow "off-on" phosphorescent aptasensor was developed based on phosphorescence resonance energy transfer (PRET) for the detection of Cd2+ in complex samples which minimizes the interference of background fluorescence. In this scheme, initially the phosphorescence of Cd2+-binding aptamer conjugated long afterglow nanoparticles (Zn2GeO4:Mn) was quenched by black hole quencher 1 (BHQ(1)) modified complementary DNA. Upon encountering of Cd2+, the aptamer interacted with Cd2+ and the complementary DNA with BHQ(1) was released, leading to phosphorescence recovery. The content of Cd2+ could be quantified by the intensity of phosphorescence recovery with 100 mu s gate time (which eliminated the sample autofluorescence) with a linear relationship between 0.5 and 50 mu g L-1 and a limit of detection (LOD) of 0.35 mu g L-1. This method was successfully demonstrated for Cd2+ detection in drinking water and yesso scallop samples. The "off-on" phosphorescent aptasensor based on PRET of long afterglow nanomaterials could be an effective tool for Cd2+ detection in food samples.