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 Cd 2+ in complex samples which minimizes the interference of background fluorescence. In this scheme, initially the phosphorescence of Cd 2+ -binding aptamer conjugated long afterglow nanoparticles (Zn 2 GeO 4 :Mn) was quenched by black hole quencher 1 (BHQ 1 ) modified complementary DNA. Upon encountering of Cd 2+ , the aptamer interacted with Cd 2+ and the complementary DNA with BHQ 1 was released, leading to phosphorescence recovery. The content of Cd 2+ could be quantified by the intensity of phosphorescence recovery with 100 μs gate time (which eliminated the sample autofluorescence) with a linear relationship between 0.5 and 50 μg L −1 and a limit of detection (LOD) of 0.35 μg L −1 . This method was successfully demonstrated for Cd 2+ 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 Cd 2+ detection in food samples. • Long afterglow Zn 2 GeO 4 :Mn nanorods were prepared with a lifetime of 16 ms. • “Off-on” was realized based on phosphorescence resonance energy transfer for Cd 2+ detection. • Time-gated phosphorescence was applied to eliminate the interface of background signal. • The aptasensor showed a linear range is 0.5–50 μg L −1 and the detection limit of 0.35 μg L −1 .