Immobilization of acetylcholinesterase on functionalized SBA-15 mesoporous molecular sieve for detection of organophosphorus and carbamate pesticide

The immobilization of acetylcholinesterase (AChE) on amino functionalized SBA-15 mesoporous sieves (NH₂-SBA-15) was explored for detection of organophosphorus and carbamate pesticides. Several methods have been studied and the “adsorption-crosslinking” is found to be the best one. Firstly, AChE and bovine serum albumin (BSA) were adsorbed in turn on the surface of NH₂-SBA-15 by electrostatic adsorption, and then glutaraldehyde was added for cross-linking the amino group of AChE. The NH₂-SBA-15 showed around 95% immobilization efficiency and the specific activity of immobilized AChE (AChE-NH₂-SBA-15) reached 130% relative to free AChE under optimal immobilization conditions. It was found AChE-NH₂-SBA-15 retained 94.0% and 82.8% of its initial activity after 60 days at 4 °C and 25 °C, respectively. It remained 55.0% of its initial activity after 6 times recycling. During the detection of pesticide, the AChE-NH₂-SBA-15 showed wider linear range and much lower limit of detection compared with free AChE. The current method showed good recovery (93.8%-109.3%) and low RSD (<5%) for both standard solution and real vegetable samples of Carbaryl and Trichlorfon. It was believed that AChE-NH₂-SBA-15 could be exploited as a fast, sensitive and low-cost biocatalyst towards the detection of pesticides residues which could be stored at room temperature for a long time.