Red light-driven photoelectrochemical biosensing for ultrasensitive and scatheless assay of tumor cells based on hypotoxic AgInS ₂ nanoparticles

A novel red light-driven photoelectrochemical (PEC) biosensing platform based on hypotoxic ternary mercaptopropionic acid (MPA)-capped AgInS ₂ nanoparticles (NPs) with excellent hydrophily and biocompatibility was proposed. AgInS ₂ NPs as a PEC sensing substrate exhibited high photon-to-current conversion efficiency under red light excitation, generating an intensive photocurrent for enhancing the sensitivity of PEC determination. After the introduction of the amino-terminated sgc8c aptamer onto the interface of AgInS ₂ NPs, the overexpressed protein tyrosine kinase-7 on the surface of lymphoblast CCRF-CEM cells could be efficiently captured. Using CCRF-CEM cell as a model analyte, an ultrasensitive PEC biosensor for scatheless assay of cells at the applied potential of 0.15 V under a red light excitation of 630 nm was designed based on the significant decline of photocurrent intensity after capturing CCRF-CEM cells. The developed PEC cytosensor demonstrated an excellent cell-capture ability, as well as a wide linear range from 1.5 × 10 ² to 3.0 × 10 ⁵ cells/mL and a low detection limit of 16 cells/mL for CCRF-CEM cells. In addition, the resulting assay method verified high selectivity and negligible cytotoxicity for cells assay. This work provided an alternative method for scatheless assay of tumor cells, which would have promising prospect in clinical diagnoses of cancer.