PROBING THE INFLUENCE OF SURFACE PROPERTIES OF NANOPARTICLES ON INTERFACIAL WATER AND LIPID MEMBRANES USING VSFG SPECTROSCOPY

Abstract

The interaction between nanoparticles (NPs) and cell membranes has garnered significant attention in the field of biomedical applications. However, studying NP-cell membrane interactions in real-time poses challenges due to the lack of suitable techniques to probe such complex interfaces. This limits our understanding of how cell membrane molecules respond to NPs exposure. In this study, vibrational sum frequency generation (VSFG) spectroscopy is employed to investigate the interactions between model lipid membranes, which mimic mammalian cell membranes, and NPs. VSFG spectroscopy is a nonlinear optical technique that provides surface-specific vibrational spectra. It has been successfully used to elucidate the organization of interfacial molecules at various interfaces. By modifying the surface properties of NPs, such as their charge, hydrophobicity, hydrophilicity, and environmental conditions (pH), we can probe the molecular interactions at the interface with high precision. For instance, at the air/water interface, charged or surface-active molecules disrupt the interfacial hydrogen bond structure, leading to changes in the VSFG water signal. Interactions of NPs with lipid monolayers not only affect the water signal but can also alter the ordering of alkyl chains and probing such interactions are crucial due to considerations of toxicity and potential medical applications. The present work discussed the distinct spectral signatures of NP interactions with model membranes, and proteins. By combining VSFG spectroscopy with complementary techniques like surface tensiometry, scanning electron microscopy (SEM), and molecular dynamics (MD) simulations, a comprehensive picture has been provided to better understand the molecular orientation and dynamics of these interactions.