Sensitive detection of organophosphorus pesticides based on the localized surface plasmon resonance and fluorescence dual-signal readout.

In this work, a dual-signal visual biosensor was designed for organophosphorus pesticides (OPs) detection using DNA functionalized Ag/Au bimetallic nanoparticles (Ag/Au NPs) as multifunctional nanoprobe. The dual-signal detection strategy was based on the inhibition of enzyme-induced H2O2 generation by OPs in the detection solution containing acetylcholinesterase (AChE), choline oxidase (CHO), acetylcholine (ACh) and nanoprobe. H2O2 produced by enzyme-catalyzed reaction could trigger the etching of Ag and dissociation of carboxyfluorescein (FAM)-labeled aptamer from the nanoprobe, resulting in significant localized surface plasmon resonance (LPRR) and fluorescence (FL) signal responses. In the presence of OPs, AChE activity was inhibited to disrupt the enzymatic generation of H2O2, which allowed to simultaneous quantitative measure OPs through the LSPR peak shifts and FL intensity variations of the nanoprobe. The LSPR/FL dual-signal biosensor showed great selectivity and sensitivity for OPs detection. In addition, two distinct colour changes were visually observed to match the LSPR/FL spectra signal responses, which was a feasible means for visual analysis of OPs. Consequently, the work provided a dual-signal visual biosensor via the combination of multifunctional nanoprobe, and had significant potential to monitor pesticide residue with high anti-interference capability and detection accuracy.