Molecular Interactions Between Silver Nanoparticles and Model Cell Membranes

Abstract

Silver (Ag) nanoparticles (NPs) are well known for their antibacterial properties. However, concerns have been raised on their possible toxicity to humans. This work is aimed to understand molecular interactions between Ag NPs and model mammalian cell membranes. Sum frequency generation (SFG) vibrational spectroscopy was used to study such interactions, supplemented by attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR). Based on the SFG and ATR–FTIR results, it was found that Ag NPs could induce flip-flop of substrate supported lipid bilayers serving as model mammalian cell membranes. The Ag NPs could accumulate onto the model cell membrane and may aggregate. The Ag NP–model cell membrane interactions depend on the Ag NP solution concentration. At low Ag NP solution concentration, lipid flip-flop was observed. At higher Ag NP concentrations, Ag NPs caused lipid flip-flop faster and might aggregate. Therefore, the lipid flip-flop rates and Ag NP accumulation/aggregation rates are directly related to the Ag NP concentration of the subphase in contact with the lipid bilayer.