Interfacial charge densities and potentials are determined for silica-supported mixed phospholipid bilayers formed from lipids having zwitterionic, negatively charged, and positively charged headgroups. Quartz crystal microbalance and atomic force microscopy demonstrate the presence of well-formed supported lipid bilayers, which, as probed by vibrational sum frequency generation, undergo negligible structural changes along their alkyl chains when the salt concentration is raised from 0.001 to 0.1 M. From second harmonic generation (SHG) measurements we estimate that each zwitterionic headgroup of the bilayer formed from pure DOPC is associated with an apparent charge of -0.028(+0.008/-0.007)�10-19 C, corresponding to 1.8 � 0.5 % of an elementary negative charge. Moreover, we show how a supported lipid bilayer carrying a negative interfacial potential may interact with not just positively charged 4-nm sized gold metal nanoparticles but also negatively charged particles at 100 mM electrolyte concentration and 10 mM Tris buffer. In this latter case, charge-charge repulsion does not appear to inhibit particle-bilayer interactions as SHG charge screening experiments are consistent with an apparent zero net charge density associated with the MPA-coated gold metal nanoparticles when they are attached to a supported lipid bilayer carrying an apparent negative potential. The results presented here serve to benchmark experimental and computational studies of the nano-bio interface.

Direct probes of supported lipid bilayers interacting with gold metal nanoparticles

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.