A sensitive and stable acetylcholinesterase biosensor with TiO2 nanoparticles anchored on graphitic carbon nanofibers for determination of organophosphate pesticides

Abstract

Electrode materials play a central role in assembling biosensors. In this work, a titanium dioxide nanoparticle loaded graphitized carbon nanofiber (TiO₂/GNF) composite is prepared for the sensitive detection of organophosphorus pesticide residues (OPs). The TiO₂/GNF composite with superior conductivity, catalytic activity and biocompatibility offers an extremely hydrophilic surface for the effective immobilization of acetylcholinesterase (AChE). Furthermore, the Ti atoms of TiO₂/GNFs could coordinate with AChE to improve its stability, and TiO₂ has a strong adsorption on OPs. The developed AChE/TiO₂/GNFs/GCE biosensor showed a high affinity to acetylthiocholine chloride (ATCh) and could catalyze the hydrolysis of ATCh with an apparent Michaelis–Menten constant (K_m) of 50 μM. The constructed AChE/TiO₂/GNFs/GCE biosensor exhibits a wide detection linear range (1.0 × 10⁻¹³ M to 1.0 × 10⁻⁸ M) with a low detection limit (3.3 fM) for paraoxon determination (a model of OPs). In addition, the developed biosensor possesses remarkable anti-interference, acceptable reproducibility and good long-term stability, and is successfully used for the determination of OPs in lake water, providing a new strategy for the analysis of OPs in ecological environments.