CoS nanoparticle-functionalized CdS nanoflowers for signal-off photoelectrochemical bioanalysis of carcinoembryonic antigens with hybridization chain reaction

In this study, a signal-off photoelectrochemical aptasensing approach was designed for quantitative screening of carcinoembryonic antigen (CEA) by using cobalt sulfide nanoparticle-functionalized cadmium sulfide nanoflowers (Co 9 S 8 @CdS) as photoactive matrix and CuS nanoparticles (NPs) as electronic extinguisher, coupling with target-induced hybridization chain reaction (HCR). The Co 9 S 8 @CdS nanohybrids, which were synthesized using a two-step thermal process, shorten the electron-migration path by virtue of their matched and close band positions, thus facilitating carrier separation and increasing photoactivity. In the sensing process of CEA, a sandwiched reaction occurred followed by the smooth implementation of the HCR, accompanied by the introduction of a huge amount of CuS NPs on the photoelectrode surface. These captured CuS NPs increased the consumption of electron donors (ascorbic acid, AA) and excitation light energy and also impeded the movement of AA toward the electrode, which synergistically led to an obvious decrease in photocurrent. Under optimum conditions, the as-designed aptasensor exhibited satisfactory analytical performance for the target CEA with a dynamic linear range from 0.02 to 40.0 ng mL −1 and a detection limit of 7.4 pg mL −1 . Besides, this sensor possessed high specificity, good stability, and acceptable accuracy. The current results suggest that our proposed strategy might have broad application prospects in the bioanalysis of disease-related markers and early disease diagnosis. (A) Schematic diagram of Co 9 S 8 nanoparticle-decorated CdS nanoflowers-based photoelectrochemical (PEC) aptasensor for the detection of carcinoembryonic antigen (CEA); and (B) the photocurrent response mechanism of PEC bioanalysis.