One-step, visual and sensitive detection of phorate in blood based on a DNA-AgNC aptasensor

The ingestion of organophosphate (Op) pesticides for attempting suicide has been a serious health issue recently. Phorate, a class of Op, has attracted attention in this regard and so the rapid diagnosis and detection of phorate is crucial for human health. In this study, a one-step and visual method for the rapid determination of phorate via an aptasensor based on DNA-templated silver nanoclusters (DNA-AgNCs) has been presented. The designed DNA-AgNC nanoprobe, containing a special structure with an intercalated aptamer, shows excellent stability. Introducing phorate to the system easily triggers the aggregation of DNA-AgNCs, producing a brown-to-colorless color change in the solution in only 6 minutes. Under the optimal conditions, the aptasensor can allow for the determination of phorate in the concentration range of 0-25 mu g mL(-1), using two linear equations: y = -2.308x + 0.996 (R-2 = 0.977) for 0-0.125 mu g mL(-1) and y = -0.020x + 0.664 (R-2 = 0.971) for 0.125-25 mu g mL(-1). The estimated detection limit of phorate was 0.012 ng mL(-1). Moreover, the practicability of this proposed method was also validated by analyzing phorate-spiked human blood samples and the results were in agreement with those from gas chromatography/mass spectrometry (GC/MS) analysis. Therefore, this fabricated aptasensor is suitable for sensing phorate in complex biological samples, and shows high potential for clinical diagnosis or forensic toxicology analysis.