Heterostructure photoelectrochemical immunosensor based on flower-like refraction structure Cd-ZnIn_2.2S_y sensitized 2D hexagonal SnS₂ nanoplates for CA242 detection

There is increasing interest in applying photoelectrochemical (PEC) analysis to the detection of biomarkers. However, it is still challenging to construct a stable and sensitive photoelectric analysis platform. The unlabeled immunosensor based on SnS2/Cd-ZnIn2.2Sy was constructed to detect carbohydrate antigen 24-2 (CA242). The hexagonal nanoflake SnS2 was used as the substrate to successfully compound three-dimensional (3D) CdZnIn2.2Sy with a flower-like structure by calcination. Due to the heterojunction formation between SnS2 and CdZnIn2.2Sy, the stepped energy levels formed facilitate electron transport and reduce the recombination of e -/h+ pairs, enhancing photoelectron unidirectional transmission capability. In addition, the 3D flower-like structure of Cd-ZnIn2.2Sy produces light refraction inside the material, resulting in an obvious photocurrent response. By efficiently immobilizing captured antibodies on the SnS2/Cd-ZnIn2.2Sy photoelectrode, a sensitive PEC immunosensor is established to detect CA242 with the detection range of 10-4 U/mL ~ 102 U/mL and the lowest detection limit of 3.06 x 10(-5 )U/mL. The PEC immunosensor constructed in this work has good repeatability, specificity and stability, indicating great application potential in improving the sensitivity of tumor marker detection.