A dual-signal amplification photoelectrochemical immunosensor for ultrasensitive detection of CYFRA 21-1 based on the synergistic effect of SnS2/SnS/Bi2S3 and ZnCdS@NPC-ZnO

•Preparing Bi2S3in situ grown on SnS2/SnS heterojunction for the first time•Developing a “dual-signal” amplification strategy based on the synergistic effect of SnS2/SnS/Bi2S3 and ZnCdS@NPC-ZnO.•Realizing ultrasensitive detection of CYFRA 21-1 by the sandwich-type PEC immunosensor. In this study, we utilized SnS2/SnS/Bi2S3 as a photoactive matrix and ZnCdS@NPC-ZnO as a signal label to construct a sandwich-type PEC immune-sensing platform. Specifically, we first applied a one-step solvothermal method to directly synthesize SnS2/SnS and form a p-n heterojunction. We then grew Bi2S3in situ on the SnS2/SnS surface, which greatly enhanced the efficiency for capturing visible light and improved the PEC signal. In addition, we labeled ZnCdS nanoparticles with a secondary antibody (Ab2) to provide a dual-signal response. Finally, we introduced NPC-ZnO, which has good adsorption performance, to the adsorbing matrix for the ZnCdS nanoparticles, which significantly accelerated the photoinduced electron transfer and further improved the sensitivity of the PEC immunosensor. As a proof-of-principle, we used the sensor to detect CYFRA 21-1 in blood plasma, a diagnostic marker of non-small cell lung cancer. Under optimized experimental conditions, the designed PEC immunosensor displayed a good linear range for CYFRA 21-1 from 0.1 pg/mL to 100 ng/mL, with a low limit of detection (LOD) of 0.06 pg/mL (S/N = 3). In summary, our data suggests that the newly developed PEC immunosensor possesses excellent selectivity and stability and has promising potential to detect biomarkers for lung cancer and other diseases.