Development of acetylcholinesterase biosensor based on platinum-carbon aerogels composite for determination of organophosphorus pesticides

A fast, sensitive and stable acetylcholinesterase (AChE) biosensor was developed based on platinum-carbon aerogels (Pt-CAs) composite to detect organophosphorous pesticides (OPs). The Pt-CAs composite was prepared by the sol-gel polymerization and the ethylene glycol liquid-phase reduction method, then was firstly used to modify boron-doped diamond (BDD) electrode for AChE immobilization. The electron transfer resistance of the Pt-CAs/BDD electrode was smaller than that of the bare BDD electrode, indicating that the presence of Pt-CAs composite on the electrode surface could improve the reactive site, reduce the interfacial resistance, and make the electron transfer easier. In comparison with AChE/BDD electrode, the negative shift of peak potential and the increase of peak current upon the oxidation of thiocholine were obtained on AChE/Pt-CAs/BDD electrode. Using methamidophos as model compound, the conditions for OPs detection were optimized. Under the optimized conditions, the inhibition rate of methamidophos and monocrotophos were linearly proportional to their concentrations in the range of 10−11-10−6 M. The detection limits were found to be 3.1 × 10−13 M (0.05 ppt) for methamidophos and 2.7 × 10−12 M (0.6 ppt) for monocrotophos. The developed biosensor exhibited good reproducibility and acceptable stability.