Molecular Interactions between Gold Nanoparticles and Model Cell Membranes: A Study of Nanoparticle Surface Charge Effect

Surface modification of nanoparticles (NPs) has been reported to play a significant role in determining their interactions with cell membranes. In this research, the interactions between carboxyl- or amine-functionalized Au NPs and model mammalian cell membranes were investigated by a nonlinear optical spectroscopic technique, sum frequency generation (SFG) vibrational spectroscopy, supplemented by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. To test the effects of surface composition on the NP–membrane interactions, we altered the ratio of different functional groups on the NP surfaces to create NPs with varied surface chemistry. In this study, a substrate-supported 1,2-distearoyl-d70-sn-glycero-3-phosphocholine (d70-DSPC or dDSPC)/1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) lipid bilayer was used as a model cell membrane. It was found that the interactions between the Au NPs and the lipid bilayer induced the lipid bilayer to flip-flop. A higher surface coverage o...