MWCNTs/CeO²-NRs-Functionalized WaveFlex Biosensor for Alkaline Phosphatase Detection in Agricultural Food Crops

Alkaline phosphatase (ALP) is a phosphomonoesterase used to hydrolyze biologically active molecules containing phosphate ester groups. Many tissues, such as bone, liver, and kidney, contain ALP; 2,4-dichlorophenoxyacetic acid (2,4-D) inhibits the reaction of ALP with phenyl phosphate. Based on the localized surface plasmon resonance (LSPR) phenomenon, a WaveFlex biosensor is designed and manufactured using multiwalled carbon nanotubes (MWCNTs)/cerium dioxide nanorods (CeO2-NRs)-immobilized multitapered fiber for detecting pesticide residues. Specifically, first, gold nanoparticles (AuNPs) are attached to the surface of the sensing region of the probe, which effectively stimulates the LSPR phenomenon. Second, MWCNTs and CeO2-NRs are fixed to the surface of the sensing region of the probe, and finally, ALP is uniformly used at a concentration of 300 IU/L. In this experiment, the authors tested the stability, repeatability, pH effect, and selectivity of the biosensor and found that it exhibits high sensitivity, good stability, and strong usability in the linear range of 0–8 mg/L, meeting the requirements for pesticide residue detection in agricultural food crops.