Influence of Silver Nanoparticles on Liposomal Membrane Properties Relevant in Photothermal Therapy

Silver nanoparticles (AgNPs) are promising agents for nanomedicine but their interactions with lipid membranes, which are a key interfaces for drug delivery, require a deeper understanding. This study investigates the influence of fructose-capped AgNPs on the physicochemical properties of SOPC-based liposomal bilayers, with potential implications for drug delivery and photothermal therapy. We employed a multitechnique approach, including infrared (IR) spectroscopy, differential scanning calorimetry (DSC), thermally induced shape fluctuation analysis, and laser irradiation at 343, 515, and 1030 nm. Our results show that AgNPs incorporated into the bilayer cause measurable perturbations: DSC reveals a decrease in the main phase transition enthalpy (from 0.280 to 0.234 J/g) and temperature (from 2.80 to 3.41 °C), while shape fluctuation analysis indicates a reduction in bending modulus (from 1.18 × 10−19 J to 0.93 × 10−19 J), confirming increased membrane fluidity. FTIR confirms interactions of fructose-capped nanoparticles and the lipid’s carbonyl and phosphate groups. Furthermore, the AgNPs-liposomes exhibit a strong, wavelength-dependent photothermal response with a temperature increase of ≈22 °C under 515 nm laser irradiation, compared to only 3–5 °C at 1030 nm. We conclude that fructose-capped AgNPs moderately fluidify lipid bilayers while enabling efficient, controllable photothermal capability, making them excellent candidates for the eventual design of advanced liposomal systems for combined therapy and diagnostics.