Dielectric Environment Engineering Enhanced Mechanisms for SERS in Biosensing

Abstract Precise dielectric modulation of localized surface plasmon resonance (LSPR) in non-metallic nanomaterials via functionalization is an unresolved fundamental problem for biological SERS sensing applications. Here, we construct MoO x @PDDA core-shell SERS nanocomposites. By engineering the dielectric environment through a hydrophilic polyelectrolyte shell (PDDA), we modulate the LSPR of non-metallic MoO x nanostructures to enhance surface-enhanced Raman scattering (SERS) activity. Finite-difference time-domain (FDTD) simulations confirm significant electromagnetic field modifications at the dielectric-engineered MoO x @PDDA interface and surrounding. This design overcomes signal attenuation in biological media, enabling in vivo SERS monitoring in plants. Quantitative analysis based on light-propagation models reveals photon scattering as the dominant signal loss mechanism, yet the nanoprobes achieve ultrasensitive metabolite detection. Our work establishes dielectric modulation as a universal strategy for designing biocompatible SERS detection, advancing fundamental understanding of non-metallic plasmonic physics in complex media.