Detecting Perfluorooctanoic Acid in Environmental Water Samples by Design of a Novel and Efficient Photoelectrochemical Sensing Platform

Contrapose the frequent occurrence of perfluorooctanoic acid (PFOA) in the environment and the serious threat to human health, it is urgent to establish effective analytical methods for monitoring PFOA levels in the environment. In this work, a novel and efficient PEC sensing platform was developed for the detection of PFOA based on CuSe/CdSe/TiO₂ nanotube arrays (NTs) composites as the photoactive material and anti-PFOA aptamer as the biorecognition element. First, CdSe quantum dots (QDs) with a narrow band gap were decorated on TiO₂ NTs surface. Furthermore, CuSe/CdSe/TiO₂ NTs composites with a p-n heterojunction structure were designed through modifying p-type semiconductor CuSe on CdSe QDs-decorated TiO₂ NTs. The as-prepared composites greatly enhanced visible light absorption and promoted charge separation, exhibiting good PEC activity. Attributed to the specific recognition of aptamer molecules immobilized on the composites toward PFOA, the formed PFOA-aptamer complexes introduced significant steric hindrance at the sensing interface, thereby impeding electron transfer and reducing the photocurrent density, and the variation in photocurrent density enabled quantitative determination of PFOA. The constructed PEC sensing platform has high sensitivity and specificity to PFOA, with a detection limit of 0.053 pg/L. Furthermore, the performance of the sensor in various environmental water samples was studied, yielding satisfactory results. Therefore, a simple and efficient PEC sensing technique has been established, providing a new solution for highly sensitive and specific detection of PFOA in the environment.