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

Abstract

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 μg mL⁻¹, using two linear equations: y = −2.308x + 0.996 (R² = 0.977) for 0–0.125 μg mL⁻¹ and y = −0.020x + 0.664 (R² = 0.971) for 0.125–25 μg 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.