Self-Powered Anti-Interference Photoelectrochemical Immunosensor Enabled by a Ferroelectric Hybrid Coupled with a Platinum-Doped Peptide Hydrogel

Accurate and sensitive detection of biomarkers in complex biofluids is critical for early disease diagnosis and clinical monitoring but remains challenging due to nonspecific interference from abundant proteins and reducing agents. Here, we present a novel self-powered, anti-interference photoelectrochemical (PEC) immunosensor that combines a ferroelectric hybrid photoanode with a platinum-doped peptide hydrogel (Pt-PH) biocathode. The photoanode was fabricated by in situ transformation of TiO₂ nanorod arrays into ferroelectric BaTiO₃ (BTO), followed by electrostatic self-assembly of sulfur-doped carbon nitride (SCN) quantum dots, forming an SCN/BTO/TiO₂ ferroelectric hybrid. The spontaneous polarization of ferroelectric BTO induces an internal electric field, enhancing charge separation and visible-light-driven photocurrent generation. The biocathode employs nitrogen-doped graphene (NG) as a conductive scaffold, coated with a Pt-PH layer derived from the short-peptide Fmoc-FEFKF doped with Pt nanoparticles, providing a highly hydrated antifouling interface that effectively suppresses nonspecific protein adsorption. The split-type configuration further minimizes interference from reducing agents in real biofluids. Using neuron-specific enolase as a model biomarker, the PEC immunosensor achieves sensitive, selective, and stable detection directly in physiological samples without external bias. This work offers a promising strategy for developing next-generation self-powered PEC biosensors with reliable antifouling performance for clinical diagnostics.