Photocathode Biosensors Based on Au Nanoparticles and ZnIn2S4/In2S3 Composites for the Detection of Exosomal MUC1 in Breast Cancer Diagnosis

The detection of exosomal MUC1 plays a crucial role in achieving a breast cancer diagnosis. In order to mitigate the risk of sample damage caused by oxidation reactions on conventional photoelectrodes in photoelectrochemical biosensors, an ultrasensitive Au nanoparticle (NP) and ZnIn2S4/In2S3 (Au/ZIS/IS) photocathodic biosensor (PCB) is developed. This study introduces Au NPs as electron conduits to redirect the transfer of photogenerated charge carriers and generate a cathodic photocurrent. Besides, a SiO2-coupled signal amplification probe system (S1– SiO2) is designed for the "signal-off" detection mode, which improves the detection signal resolution. In addition, the mechanism of cathodic photocurrent generation is also discussed, which intended to provide experience for follow-up work. The Au/ZIS/IS PCB is found to have excellent performance in terms of sensitivity and specificity, with a linear range from 7.3 × 102 to 7.3 × 108 particles/μL and a calculated detection limit of 78 particles/μL. The analysis of clinical samples reveals significant differences between healthy controls and breast cancer patients, demonstrating great potential for clinical applications.