A dual-mode sensor platform with adjustable electrochemiluminescence-fluorescence for selective detection of paraquat pesticide

This study presents functionalized metal–organic frameworks nanosheets (RuMOFNSs) with strong electrochemiluminescence (ECL) and fluorescence (FL) properties and a novel signal marker-tetraferrocene. Based on the efficient quenching effect of the tetraferrocene on RuMOFNSs, a “signal switch” ECL-FL dual-mode sensor is constructed for sensitive detection of paraquat (PQ). ECL and FL signals are annihilated after adding paraquat-aptamer DNA (PQ-Apt DNA) labeled with tetraferrocene since it is close to RuMOFNSs. PQ is added, and the strong binding and intermolecular interaction between PQ-Apt DNA and PQ induces spatial separation, with tetraferrocene groups far away from RuMOFNSs. At this point, ECL and FL signals are restored. The change in ECL and FL signals realized the quantitative determination of the PQ solution. In addition, the dual-mode sensor exhibits high sensitivity and specificity with detection limits as low as 0.008 ng/mL and 0.059 ng/mL. The proposed sensor is successfully applied to determine PQ, indicating its great application potential in the food industry.