The visible light-driven and self-powered photoelectrochemical biosensor for organophosphate pesticides detection based on nitrogen doped carbon quantum dots for the signal amplification

Abstract A novel visible light driven self-powdered photoelectrochemical (PEC) biosensor was constructed for organophosphorus pesticides (OPs). The biosensor was prepared by taking indium tin oxide (ITO) as the substrate, titanium dioxide (TiO2) nanoparticles as the photoactive substrate material, nitrogen-doped carbon quantum dots (NCQDs) as the photosensitizer and acetylcholinesterase (AChE) as the biorecognition molecule. Because of the excellent optical performances of NCQDs, the photocurrent response of the NCQD/TiO2/ITO electrode were improved obviously compared with TiO2/ITO electrode. The AChE immobilized on the surface of the PEC biosensor can catalytic hydrolysis of acetylcholine chloride (ATCl) to generate thiocholine, which can serve as the electron donor to enhance the separation of the photogenerated electron-hole pairs, therefore, the photocurrent response of the PEC biosensor elevated greatly. The bioactivity of the AChE was inhibited by OPs where chlorpyrifos was used as the model, the production of the thiocholine was declined, leading to a reduction of the photocurrent response. The prepared PEC biosensor can achieve the sensitive detection of chlorpyrifos with the board detection range varied from 0.001 μg mL−1 to 1.5 μg mL−1 and the detection limit was about 0.07 ng mL−1 (S/N = 3). It is the first time that NCQDs/TiO2 is adopted to construct the PEC biosensor for chlorpyrifos detection. The obtained PEC biosensor can also achieve the detection of chlorpyrifos in the lake water and Chinese cabbage samples, suggesting that the fabricated PEC biosensor had potential application for the detection of OPs in environment and food.