Spatial nanopores-assisted biomimetic nanozymes for sensitive detection of organophosphorus pesticide in real samples

Biomimetic nanozymes opens up new opportunities for sensitive, rapid and field detection of organophosphorus pesticides (OPs). However, it still remains challenges in how to improve the sensitivity and stability of biomimetic nanozymes under harsh conditions. Herein, we synthesized a novel biomimetic nanozyme composed of hemin and bovine serum albumin (BSA) in the nanopores of poly-L-lysine methacryloyl (PLMA) inverse opal hydrogel (PLMA-Hemin-BSA). PLMA-Hemin-BSA achieves superior peroxidase-like activity and shows high stability due to the confinement effect. A multi-enzyme cascade reaction was constructed for the colorimetric detection of five widely used OPs by integrating PLMA-Hemin-BSA with natural choline oxidase and acetylcholinesterase. The detection limits for dichlorvos, chlorpyrifos, paraoxon, methamidophos, and parathion were as low as 0.024, 0.073, 0.12, 0.56, and 1.4 ng/mL, respectively. More importantly, the average recovery rates and the relative standard deviations (RSD) of chlorpyrifos in paddy water, soil and wheat samples were 86.62 %-100.13 % and 2.08 %-8.65 %, which meet the standard of the International Union of Pure and Applied Chemistry (IUPAC, recoveries of 70 %-120 % with RSD < 20 %). This study represented advanced methods toward enhancing the activity and stability of biomimetic nanozymes via spatial nanopores-assisted strategy.