Magnetically controlled all-in-one sensing platform for triple-mode detection of organophosphorus pesticides using DNA tetrahedrons-polydopamine reporters.

Accurate and on-site detection of organophosphorus pesticides (OPs) in complex matrixes is important for environmental monitoring and food safety. Herein, a colorimetric (CL), photothermal (PT) and fluorescence (FL) triple-mode sensor was constructed for OPs detection based on magnetically controlled all-in-one platform, which was featured of specific recognition unit, abundant loading of DNA tetrahedrons-Fe3+-polydopamine (TDN-Fe3+-PDA) with peroxidase-like activity, and verifiable triple-mode signal output. Based on the aptamer-target recognition and efficient separation of MBs, large amount of TDN-Fe3+-PDA reporters was released. Taking full advantages of the supernatant and precipitation, OPs was sensitively detected with the TDN-Fe3+-PDA catalyzed 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 system (CL mode), photothermal effect of TDN-Fe3+-PDA and oxidized TMB (oxTMB) (PT mode), and fluorescent signal of TDN-templated copper nanoclusters on MBs (FL mode). Using profenofos (Pro) as the model target, the triple-mode sensing platform realized sensitive detection of Pro with the detection limits 0.23 ng/mL, 0.40 ng/mL and 0.14 ng/mL for CL, PT and FL mode, respectively. The proposed strategy provided a simple and accurate method for on-site detection of OPs, holding promising application in environmental and food contamination monitoring.