Heterostructure photoelectrochemical immunosensor based on flower-like refraction structure Cd-ZnIn2.2Sy sensitized 2D hexagonal SnS2 nanoplates for CA242 detection

Abstract

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) Cd-ZnIn2.2Sy with a flower-like structure by calcination. Due to the heterojunction formation between SnS2 and Cd-ZnIn2.2Sy, 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 × 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.