A novel acetylcholinesterase biosensor with dual-recognized strategy based on molecularly imprinted polymer

Biosensors using acetylcholinesterase (AChE) as the recognition element detect both toxicity (AChE inhibition activity) and concentration of organophosphorus pesticides (OPs). However, real application of these biosensors remains a challenge due to their low selectivity and low resistance to sample matrix, interferences and hash analytical conditions. In this study, a novel dual-recognized strategy was established by using molecularly imprinted polymer (MIP) and AChE selective to different moieties of acephate (AP) as affinity molecules simultaneously. Using AP as the model OP, MIP highly selective to certain moieties but not phosphorus of AP was prepared on the surface of microplate by self-polymerization of dopamine. The MIP enriched AP from samples selectively. Then AChE selective to phosphorus of AP quantified the levels of AP captured by MIP. AP captured by MIP still inhibited the activity of AChE because the affinity of AP to AChE was higher than to MIP. By incorporating selective sample pretreatment with AChE inhibition assay in one sensor, the biosensor identified AP from other OPs, carbamates pesticides and interferences commonly found in food and environmental samples. When vegetables with high matrix effect on AChE inhibition assay were analyzed, selective sample pretreatment ensured the biosensor to detect AP more accurately and selectively than classical AChE inhibition assay. The results of the biosensor had no statistical difference compared with those of HPLC-MS/MS. The dual-recognized strategy may provide a new solution to detect target enzyme inhibitors in complicated samples using enzyme-based biosensors selectively and accurately.