Post-Synthesis of Organically Grafted Nanoporous Carbon for Acetylcholinesterase Activity Improvement and Organophosphate Pesticide Detection

A novel organically modified mesocellular carbon foam (OMCF) was synthesized to enhance the bioactivity of acetylcholinesterase (AChE) and integrated with gold nanoparticles to fabricate amperometric biosensor for ultrasensitive detection of organophosphate pesticide (OP) in drinking water. The OMCF was prepared by functionalizing MCF with o-phenylenediamine through a post-synthesis procedure. The organically modification process produced plentiful amino group on the mesowall, resulting in a benign microenvironment inside the MCF. Further N₂ sorption isotherms and IR spectra studies indicated the OMCF had well distributed mesopores and functional groups on the mesowalls. AChE was entrapped in the mesopores of OMCF via physical adsorption, and the bioactivity of the enzyme encapsulated in OMCF was measured to be 1.33 times higher than that in solution by UV-vis spectrometer. Electrochemical impedance spectra studies indicated the introduction of gold nanoparticles could further improve the conductivity of the solid matrix. Based on the inhibition action of OP on AChE, the OMCF based AChE electrochemical biosensor showed a wide linear range (0.05 ppb to 5 ppb) toward monocrotophos, a model highly toxic OP, and high accuracy and good reproducibility in drinking water analysis.