Harnessing the synergy of gold nanoparticles and lipid membranes for biomedical applications

The interaction between gold nanoparticles (AuNPs) and lipid membranes has long been explored to better understand the biological behavior of nanomaterials and to uncover the mechanisms occurring at the nano-bio interface. Over the years, studies on this AuNP-lipid membrane interplay have advanced significantly, revealing the physicochemical principles that govern AuNP behavior, ultimately paving the way for guiding the development of innovative analytical and nanomedical technologies. In this context, previous studies have shown that citrate-capped AuNPs spontaneously aggregate on synthetic zwitterionic membranes through a membrane-templated process that depends on the rigidity of the membrane and the surface functionalization of AuNPs. In the present thesis, this spontaneous interaction is thoroughly investigated, aiming at exploring potential innovative biomedical applications arising from AuNPs-lipid membrane combination. Accordingly, the first section of this work focuses on exploiting the plasmonic properties of AuNPs to characterize synthetic and natural lipid vesicles. Specifically, we propose the use of nanoplasmonic isosbestic points, i.e., characteristic wavelengths where the total absorbance of a system remains constant during a chemical or physical transformation, as reliable, concentration-independent optical indicators of membrane stiffness, thereby revealing how membrane rigidity affects nanoparticle interactions. Then, in the second section, we demonstrated that the self-assembly of AuNPs on liposomal membranes can be harnessed to fabricate tunable, reproducible, and sensitive nanoprobes, suitable for molecular surface-enhanced Raman scattering (SERS)-based detection and bioanalytical applications. Finally, the last part of the work extends the production of AuNP-lipid hybrids to more structurally complex, non-lamellar lipid systems, opening promising perspectives for the development of advanced plasmonic-lipid materials for biomedical sensing. In conclusion, the results presented in this work highlight the functional synergy between AuNPs and lipid assemblies, demonstrating how their combination can be strategically leveraged to design multifunctional platforms with significant relevance in the field of Nanomedicine.