Highly sensitive visible light activated photoelectrochemical biosensing of organophosphate pesticide using biofunctional crossed bismuth oxyiodide flake arrays.

A new, highly sensitive and selective biosensor for the photoelectrochemical (PEC) detection of organophosphate pesticides (OPs) has been developed, whereby newly synthesized crossed bismuth oxyiodide (BiOI) nanoflake arrays (BiOINFs) are fabricated as a photoactive electrode via a successive ionic layer adsorption and reaction (SILAR) approach. The smart integration of BiOINFs with biomolecules acetylcholinesterase (AChE) yields a novel AChE-BiOINFs hybrid, constructing a three-dimensional (3D) porous network biosensing platform. The composition and surface structure of the sensor were carefully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and various electrochemical techniques. Such interlaced network architectures, providing better mass transport and allowing more AChE loading per unit area, as well as the intrinsically strong visible light-harvesting effect from BiOI, greatly facilitate the PEC responses. On the basis of the effect of OPs on the photocurrent of AChE-BiOINFs/ITO, a highly sensitive visible light-activated photoelectrochemical biosensor was developed for biosensing OPs. The conditions for OPs detection were optimized by using methyl parathion (MP) as a model OP compound. Under the optimized experimental conditions, our results show that such a newly designed AChE-BiOINFs/ITO photoactive electrode provides remarkably improved sensitivity and selectivity for the biosensing of OPs. The detection limit was found to be as low as about 0.04 ng mL(-1) (S/N=3). Toward the goal for practical applications, the resulting sensor was further evaluated by monitoring MP in spiked vegetable samples, showing fine applicability for the detection of MP in real samples.