Visible light photoelectrochemical aptasensor for adenosine detection based on CdS/PPy/g-C3N4 nanocomposites

In this work, a label-free photoelectrochemical (PEC) aptasensor was developed for adenosine detection based on CdS/PPy/g-C3N4 nanocomposites. The CdS/g-C3N4 heterojunction effectively prevented the photogenerated charges recombination of g-C3N4 and self-photocorrosion processes of CdS, improving photo-to-current conversion efficiency. The introduced polypyrrole (PPy) nanoparticles could lead to a more effective separation of photogenerated charges, thus resulting in a further increasing of photocurrent. The CdS/PPy/g-C3N4 was firstly employed as the photoactive materials for fabrication of aptasensor, and SH-aptamer was then adsorbed on the CdS/PPy/g-C3N4 modified electrodes through S-Cd bond. With increasing of adenosine concentration, the photocurrent decreased as the formation of SH-aptamer-adenosine bioaffinity complexes. Under optimal conditions, the PEC aptasensor had a sensitive response to adenosine in a linear range of 0.3 nmol L−1 to 200 nmol L−1 with a detection limit of 0.1 nmol L−1. Besides, the as-proposed aptasensor has also been applied in human serum samples analysis. The aptasensor exhibits high sensitivity and good stability, thus opening up a new promising PEC platform for some other small molecules analysis.