Localized surface plasmon resonance enhanced label-free photoelectrochemical immunoassay by Au-MoS₂ nanohybrid

Recently developed localized surface plasmon resonance (LSPR) enhanced photoelectrochemical (PEC) biosensing has emerged as a unique label-free technology owing to the high sensitivity and robust detection. Herein, a feasible PEC biosensing platform based on receptor-functionalized plasmonic Au-MoS₂ nanosheets was designed for the capture of target proteins. The biomolecular interaction substantially enhances the hot electron transfer efficiency between Au and MoS₂, leading to a direct change in electrocatalytic current on MoS₂ as electricity readout signal. The biosensor exhibits excellent analytical performance for protein detection in a range from 41.7 nM to 4.17 μM, with a detection limit of 4.17 nM. Additionally, this system also affords real-time analysis of binding kinetics between antigen and antibody, allowing for obtaining their rate constants of association/disassociation (k_on/k_off) and equilibrium constant K_d of 3.95 μM. LSPR-enhanced label-free PEC monitoring system, without the participation of ultraviolet excitation and sacrifice agents, bears no harm to biomolecules and shows high-sensitivity detection, which holds great potential applications in clinical and biological analyses.