A Highly Antifouling and Dual-Responsive PEC-FL Biosensor for Prostate-Specific Antigen Based on DNA Micelle Signal Converter and 3-D Self-Supporting Multivariate Heterojunction

While the potential of photoelectrochemical-fluorescence (PEC-FL) dual-mode sensing platforms has been established, traditional unidirectional signal output mode is prone to signal cross-interference from dissimilar signaling routes and lack inherent error correction. In this study, we introduced a dual-responsive (“SIGNAL-OFF” PEC and “SIGNAL-ON” FL) and antifouling PEC-FL dual-signal biosensor for detecting prostate-specific antigen (PSA) in biofluid samples. Initially, a DNA micelle-based signal converter system resembling a “three-way valve” was constructed through target activation, CRISPR-Cas12a inactivation, and DNA-cholesterol self-assembly. Then, the DNA monomers in DNA micelle were extended by terminal deoxynucleotidyl transferase and hybridized with biotin-DNA on magnetic Fe3O4 to form magnetic copper nanoparticles (Cu NPs) through incubation with copper sulfate and ascorbic acid. A notable increase in fluorescent signal was observed from magnetic Cu NPs. The subsequent lysis treatments of the Cu NPs facilitated the release of numerous Cu $^{{2}+}$ , which interacted with CdS QDs of the 3-D self-supporting TiO2-ZnO@CdS electrode, resulting in the formation of CuS and creation a tailored “SIGNAL-OFF” PEC mode for PSA determination. In our system, the DNA micelle-based signal converter system facilitates the synchronized conversion of PEC and FL signals to enable reciprocal validation. The dual-responsive signals result in robust and quantitative detection with an FL detection limit of $0.613~\text {fg}\cdot \text {mL}^{-{1}}$ and a PEC detection limit of $0.723~\text {fg}\cdot \text {mL}^{-{1}}$ . In addition, this split mode ensures autonomous biological recognition and signal reporting, thereby improving measurement accuracy. The proposed methodology offers the capability to quantify PSA in human serum and pays the way to the simultaneous acquisition of dual signals.