The effect of cholesterol on protein-coated gold nanoparticle binding to liquid crystal-supported models of cell membranes

We report an easily visualized liquid crystal (LC)-based system to study the biophysical interactions between protein-coated gold nanoparticles (AuNPs) and LC-supported cell membrane model. The model consists of mixed phospholipid/cholesterol monolayer self-assembled at aqueous–LC interface. Protein-coated AuNPs were found to disrupt the mixed phospholipid/cholesterol monolayer. As a result, orientational transitions of LCs were triggered and optical responses of LCs from dark to bright were observed. The mixed monolayers with higher cholesterol contents were found to be more susceptible to the disruption by protein-coated AuNPs, and hydrophobic interaction played a major role in the monolayer disruption. We also found that the time for non-specific binding of fibrinogen-coated AuNPs to the mixed phospholipid/cholesterol monolayer was similar to that of specific binding of neutravidin-coated AuNPs to the mixed phospholipid/biotin-capped phospholipid monolayer. Results obtained from this study may offer new understanding in the potential nanotoxicity pathway, where the biophysical interaction between nanomaterials and cell membrane is an important step.