The inhibition mechanism of 2,4-dichlorophenoxyacetic acid (2,4-D) to catalase was studied by a catalase biosensor in a flow-injection analysis (FIA) system. This system provides an ideal sensing platform to electrochemically evaluate the chemical mechanism of enzyme inhibition. Hierarchical porous calcium phosphate (hp-CaP), as a biocompatible nanomaterial, was used to immobilize catalase for repeat use. 2,4-D together with H 2 O 2 was injected into the bioreactor of the immobilized catalase-FIA system during the experimental procedure. The activity of the immobilized catalase was inhibited, which caused a decrease of the catalase-catalyzed H 2 O 2 reduction current. Lineweaver−Burk, Dixon, and Cornish−Bowden plots confirmed that the inhibition of catalase by 2,4-D followed an competitive mechanism with a inhibition constant of 4.78 × 10 −7 M. Based on this inhibition characters, a biosensor for 2,4-D detection was constructed. This biosensor showed a linear range from 0.03 to 3.00 μM with a detection limit of 0.015 μM. It demonstrated good stability, acceptable reproducibility and low cost for 2,4-D screening. It has been successfully applied for the determination of 2,4-D in commercial bean sprouts samples. It is anticipated that a rapid evaluation of the chemical mechanism of catalase inhibition by the FIA system could pave the way to rationally designing biosensors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.