Carbon dots loaded liposomes amplified polarity-reversal photoelectrochemical biosensor for the assay of breast cancer exosomal surface proteins.

Breast cancer (BC) has become the top women killer worldwide. Exosomes carry plentiful tumor-specific proteins guiding the pathological progression and reflecting heterogeneity of their parent cells. The sensitive and differental analysis of exosomal Mucin 1 (MUC1) and programmed death-ligand 1 (PD-L1) proteins is very significant for early and accurate diagnosis and prognosis of breast cancer. Herein, a carbon dots (CDs)-induced ZnIn2S4 (ZIS) photocurrent polarity-reversal strategy is first proposed and applied to photoelectrochemical (PEC) biosensor for the assay of breast cancer exosomal surface proteins by smart integrating with split-type mode and aptamer labeled-carbon dots-loaded liposomes (CDs-Lip-Apt) amplification strategy. After biorecognition and subsequent lysis treatment, numerous CDs are released to induce photocurrent polarity-reversal of the ZIS modified photoelectrode. Noteworthy, the elegant polarity-reversal PEC sensing strategy not only enhances the detection accuracy owning to anti-interference ability toward background signals and potential interferences but also increases the detection sensitivity and range due to larger target-related signal changes. Furthermore, the detection sensitivity and accuracy of the polarity-reversal PEC biosensor are improved by smart integrating with split-type mode and aptamer labeled-carbon dots-loaded liposomes (CDs-Lip-Apt) amplification strategy. Moreover, the fabricated polarity-reversal PEC sensor allows profiling exosomal MUC1 and PD-L1 proteins and identifying of the source of multiple breast cancer exosomes. The present sensor not only open a novel avenue for precise identification of exosomes and cells heterogeneity, but also providing a promising tool in clinical diagnostics.