N, O dual-coordinated HCNs@Fe single-atom nanozymes with enhanced peroxidase-like activity for portable detection of acetylcholinesterase activity and its pesticide inhibitors.

Single-atom nanozymes (SAzymes) exhibit superior catalytic activity, making it a promising candidate for constructing biosensors. Herein, we constructed a hollow carbon nanocages supported, N and O double-coordinated Fe SAzymes (HCNs@Fe SAs) through a template and pyrolysis strategy. Abundant oxygen atoms in pre-modified template SiO@resorcinol-formaldehyde provided enough binding sites and promoted the dispersion and stabilization of metal atoms. Compared with non-O modified nanozymes, HCNs@Fe SAs exhibited an 8-fold enhancement in catalytic efficiency. Benefiting from its exceptional peroxide-like activity, a straightforward and dependable colorimetric sensing platform was developed to assess the activity of Acetylcholinesterase and its inhibitor organophosphorus pesticide (OP) in real water samples and fruit substrates, with the limit of detection of 0.02318 mU mL and 0.85 ng mL, respectively. An OPs test paper was also designed for point-of-care determination of OP with satisfactory sensitivity. This study provides a new strategy of template pre-modification to design SAzymes with enhanced catalytic efficiency.