Peptide Cleavage-Mediated and Environmentally Friendly Photocurrent Polarity Switching System for Prostate-Specific...

As the most important serum biomarker for prostate cancer, sensitive and accurate detection of prostate-specific antigen (PSA) is of great reference value for the clinical diagnosis and treatment of prostate cancer. Herein, a peptide cleavage-mediated and environmentally friendly photocurrent polarity switching system was developed for ultrasensitive and highly selective detection of PSA based on the efficiently switching of photocurrent polarity of silver indium sulfide nanoparticles (AgInS₂ NPs)-coated indium tin oxide (ITO) electrode by amino-functionalized CuO cubes (NH₂-CuO). The porous CuO cubes were synthesized by calcination of HKUST-1 and functionalized with aminosilane. In the presence of PSA, the biotin and rhodamine B-labeled peptide (Bio-Pep-RhB) was cleaved and part of the peptide (P-Pep-RhB) was obtained by magnetic separation. Through host-guest recognition between β-CD and RhB, the P-Pep-RhB was immobilized on the β-CD/AgInS₂ NPs/ITO electrode. Then, the amino-rich sequence on P-Pep-RhB combined with NH₂-CuO via glutaraldehyde results in the switch of anodic photocurrent to cathodic photocurrent. On account of the high-efficient peptide cleaving strategy and the new photocurrent polarity switching system of porous CuO cubes//AgInS₂ NPs, the prepared sensing platform displayed outstanding analytical performance for PSA with a wide linear response range (0.1 pg mL^-1-100 ng mL^-1) and a lower detection limit of 0.06 pg mL^-1. The proposed analytical method could be easily extended to analyze other proteins via changing the peptide sequence, which has a potential application in the fields of biological analysis and medical diagnosis.