Cerium Dioxide-NRs/Tungsten Disulfide-Quantum Dots Functionalized W-Shaped WaveFlex Biosensor for Rapid Detection of Paraoxon Pesticide in Agricultural Products

In this work, a sensitive and portable fiber-optic WaveFlex biosensor is developed for the detection of paraoxon pesticide in agricultural products. A combination of simulation and experiment is used to analyze the distribution of the evanescent field in optical fiber. The flexible W-shaped optical fiber biosensor (OFB) based on localized surface plasmon resonance (LSPR) effect is developed, also known as WaveFlex biosensor. Gold nanoparticles (AuNPs) were immobilized on the surface of the optical fiber probe to successfully excite the LSPR phenomenon. In addition, in order to modify the optical fiber probe, cerium dioxide nanorods (CeO2-NRs) and tungsten disulfide quantum dots (WS2-QDs) were functionalized. It is used to enhance the biocompatibility of the sensor and increase the specific surface area of the fiber probe. The enzymatic determination of organophosphorus pesticides (OPs) is usually based on cholinesterase and organophosphorus hydrolase. Paraoxon has an irreversible inhibitory effect on butyrylcholinesterase. The content of paraoxon was detected by the inhibitory effect of paraoxon on butyrylcholinesterase. The reproducibility, reusability, stability, selectivity, and pH tests of the W-shaped WaveFlex sensor and its application in real samples are evaluated using different concentrations of paraoxon solution. The linear range of the sensor is 0–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100~\mu $ </tex-math></inline-formula>g/mL, and the limit of detection (LoD) is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.999~\mu $ </tex-math></inline-formula>g/mL. The sensitivity is as high as 0.0312 nm/(<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>g/mL), which verifies that the sensor provides an indispensable technology, cost-effective and portable solution for paraoxon-specific detection.