Sensitive and selective electrochemical biosensor based on ELP-OPH/BSA/TiO₂NFs/AuNPs for determination of organophosphate pesticides with p-nitrophenyl substituent

We report herein a new electrochemical bisosensor based on elastin-like polypeptide-organophosphate hydrolase/bovine serum albumin/titanium oxide nanofibers/gold nanoparticles (ELP-OPH/BSA/TiO2NFs/AuNPs) for highly sensitive and selective, rapid, one-step determination of organophosphate pesticides (OPs) with p-nitrophenyl substituent. ELP-OPH was purified from genetically engineered Escherichia coli (E. coli) taking the advantage of thermal-triggered phase-transition of ELP. The surface morphology and crystal structure of the as-prepared ELP-OPH/BSA/TiO₂NFs/AuNPs nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray Diffraction (XRD), respectively. The electrochemical properties and catalytic behavior of the as-prepared electrodes for the determination of methyl parathion were systematically investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry (i–t). During OPs detection, OP compounds were selectively adsorbed to the TiO₂NFs surface due to the strong affinity of its phosphoric group with TiO₂NFs, while AuNPs were employed to provide a stable interface for promoting electron transfer between biomolecules and electrodes, thus enhanced sensing performance was accomplished. Under the optimized operating conditions, the as-prepared biosensor can detect methyl parathion with a wide dynamic ranges (up to 116.4 μM), a good sensitivity of 734 μA cm⁻² mM−¹ and the limit of detection (S/N = 3) as low as 29 nM. Its further application for determination of methyl parathion spiked into lake water samples was also demonstrated with an acceptable stability. All these features indicate that the as-developed ELP-OPH/BSA/TiO₂NFs/AuNPs/GCE holds great promise in rapid, sensitive, specific, and reliable detection of organophosphates pesticides.