Driving Adsorbed Gold Nanoparticle Assembly by Merging Lipid Gel/Fluid Interfaces

Surface forces between inorganic nanopartides and lipid bilayer is of great relevance to biophysics, medicine, and nanobiotechnology. Adsorbed nanopartides may influence the fluidity of the underlying lipids, which may in turn influence nanoparticle assembly. Herein three types of lipids (DOPC, T-c = -20 degrees C; DMPC, T-c = 23 degrees C; and DPPC, T-c = 41 degrees C) are used, all with the same phosphocholine (PC) headgroup. Gold nanop article (AuNP) color change is monitored as a function of lipid phase transition temperature (T-c), surface ligands on AuNPs, and temperature. Liposomes with higher fluidity induce much faster aggregation of AuNPs. Aside from the kinetic aspect of faster diffusion on fluid bilayers, this faster color change is attributed to the local lipid gelation and merging of gelled regions to eliminate the interface between different lipid phases.