Highly Selective and Sensitive Photoelectrochemical Sensing Platform for VEGF165 Assay Based on the Switching of Photocurrent Polarity of CdS QDs by Porous CuO-CuO Flower.

Herein, a highly selective and sensitive photoelectrochemical (PEC) sensing platform was developed for vascular endothelial growth factor 165 (VEGF165) assay based on the porous CuO-CuO flower-induced photocurrent-polarity switching of the CdS quantum dots (QDs) modified indium-tin oxide (ITO) electrode. The porous CuO-CuO flower with uniform size and large surface area was successfully synthesized by taking Cu-MOF (HKUST-1) as the precursor. Through VEGF165-triggered catalytic hairpin assembly process, the porous CuO-CuO flower was introduced to the surface of the CdS QDs/ITO electrode, resulting in the switching of the photocurrent polarity from anodic current to cathodic current. Based on the uniform particle size, high specific surface area, good photoelectric conversion efficiency, and photocurrent polarity switching ability of porous CuO-CuO flower, the proposed sensing platform showed excellent assay performance for VEGF165 with a linear response range from 1 to 3000 fM, a detection limit of 0.3 fM, and high selectivity. By changing the specific aptamer, the proposed sensing platform could be easily extended to detect other proteins, and may have a promising application in bioanalysis and early disease diagnosis.