Biosensor based on acetylcholinesterase immobilized onto layered double hydroxides for flow injection/amperometric detection of organophosphate pesticides

We developed a highly sensitive flow injection/amperometric biosensor for the detection of organophosphate pesticides (OPs) using layered double hydroxides (LDHs) as the immobilization matrix of acetylcholinesterase (AChE). LDHs provided a biocompatible microenvironment to keep the bioactivity of AChE, due to the intrinsic properties of LDHs (such as a regular structure, good mechanical, chemical and thermal stabilities, and swelling properties). By integrating the flow injection analysis (FIA) with amperometric detection, the resulting AChE-LDHs modified electrode greatly catalyzed the oxidation of the enzymatically generated thiocholine product, and facilitated the detection automation, thus increasing the detection sensitivity. The analytical conditions for the FIA/amperometric detection of OPs were optimized by using methyl parathion (MP) as a model. The inhibition of MP was proportional to its concentration ranging from 0.005 to 0.3 μg mL−1 and 0.3 to 4.0 μg mL−1 with a detection limit 0.6 ng mL−1 (S/N=3). The developed biosensor exhibited good reproducibility and acceptable stability.

► LDHs as the immobilized matrix of enzyme. ► LDHs with swelling properties keep the bioactivity of LDHs well. ► Amperometric analysis coupled with flow-injection analysis. ► A highly sensitive biosensor for FIA/amperometric detection of OPs developed.