Plasmonic behaviour of poly(2-ethyl-2-oxazoline)-coated gold nanoparticles for sensing and temperature-control applications.

Gold nanoparticles functionalized with xanthate-poly(2-ethyl-2-oxazoline) (PEtOx-AuNPs) were investigated as thermoresponsive hybrid nanomaterials with tunable optical and thermal properties. The PEtOx-AuNPs exhibited changes in surface plasmon resonance (SPR) and amplified Surface-Enhanced Raman Scattering (SERS) signals during the reversible lower critical solution temperature (LCST) transition of the PEtOx ligand. The effect of the PEtOx coating on the photophysical properties of AuNPs, particularly on heat generation efficiency upon photoexcitation by Z-scan photothermal lens spectroscopy, was investigated. The results demonstrate the potential of PEtOx-AuNPs for applications in temperature-sensitive drug delivery, photothermal therapy, nanoscale heat generation, and photonic devices.