Photoelectrochemical Immuno-Sensing via Plasmon-Induced Resonance Energy Transfer Mechanism

Photoelectrochemical (PEC) sensors integrate light excitation with electrochemical detection, providing low background noise and robust anti-interference capabilities. Surface plasmon resonance (SPR) acts as an effective light antenna for signal transduction in these sensors. Traditionally, plasmon-mediated PEC sensors operate via hot carrier injection, which necessitates direct contact between the plasmonic antenna and the semiconductor, thereby limiting sensor design flexibility. In this work, we introduce plasmon-induced resonance energy transfer (PIRET) as a novel signal transduction mechanism in a PEC immunosensor. A Bi₃FeMo₂O₁₂ (BFMO) semiconductor thin film is functionalized with capture antibodies, while plasmonic Au nanoparticles with absorption spectrum overlapping with BFMO are conjugated to detection antibodies. Upon target antigen binding, the Au nanoparticles are positioned in proximity to the BFMO surface through a sandwich immunoassay configuration, enabling PIRET-mediated generation of electron-hole pairs in BFMO. Using human IgG as a model analyte, we demonstrate the feasibility and advantages of PIRET, highlighting its potential to extend PEC sensor design by permitting a physical gap between the plasmonic antenna and semiconductor.