An Anti-interference PEC-ECL Biosensing for Cancer-related Gene based on Self-supporting Semi-encapsulated Heterojunction Modulated Interface Polarity-Switching

A novel dual-polarity switching photoelectrochemical-electrochemiluminescence (PEC-ECL) dual-signal biosensor has been developed to detect cancer-related gene (TP53) in biofluids, addressing the limitations of conventional PEC systems that typically operate in a unidirectional mode, making them susceptible to interference and lacking error correction mechanisms. The new platform utilizes self-supporting N-doped TiO₂ nanofibers synthesized via electrospinning to function as an anodic PEC signal generator. Integrating gold nanoparticles (AuNPs) into the N-TiO₂ nanofibers forms a Schottky junction, enhancing hot electron transfer through the localized surface plasmon resonance (LSPR) effect of AuNPs, allowing cathodic photocurrent generation under visible light. The detection mechanism is further enhanced by a TP53-triggered rolling circle amplification (RCA) reaction, which produces DNA-CdS quantum dot (QDs) nanostrings that hybridize with N-TiO₂@Au, creating semi-encapsulated heterojunctions (N-TiO₂@Au@CdS) that significantly amplify the anodic photocurrent and reinstate the anodic "on" PEC state. Simultaneously, the proposed heterojunction generates a strong ECL signal in the presence of S₂O₈^2-. The dual-polarity switching capability allows for effective differentiation of the target from coexisting redox disruptors, enhancing detection reliability. The synergistic effects of the extended DNA scaffold from RCA programmed CdS QDs and the strong LSPR effect of AuNPs create high-density carriers with high energy, resulting in enhanced and reproducible PEC and ECL signals. The biosensor achieves detection limits of 0.064 fM for PEC and 1.66 fM for ECL, with excellent stability and applicability in real samples, providing a robust platform for diagnosing and prognosing TP53-related diseases.