Lipid Bilayer Templated Gold Nanoparticles Nanoring Formation Using Zirconium Ion Coordination Chemistry

Abstract

We used positively charged lipids to prepare lipid bilayer assemblies (LBAs) upon which we assembled negatively charged gold nanoparticles (AuNPs). Treatment of the assembly with zirconium chloride resulted in the formation of nanorings of the diameters inversely related to the zirconium ion concentration. The nanorings were attributed to the zirconium ion coordinated AuNPs formed during the lipid bilayer budding process promoted by the acid effect of zirconium chloride. Nanoring organization was also dependent on the fluidity of lipid bilayers, an indication of LBA-assisted nanomaterials organization. We suggest that such bioorganic-inorganic hybrid assemblies coupled to unique topological and morphological variations might be useful as stimuli-responsive sensors or storage compartments for proteins or drugs.

Lipopolysaccharide-Induced Dynamic Lipid Membrane Reorganization: Tubules, Perforations, and Stacks

“…Perforation of lipid membranes by LPS was suggested by previous indirect evidence of electrical resistance of lipid membranes stretched across an aperture where treatment with LPS (110-720 mg/mL) led to a decreased resistance and eventual collapse (60). Holes and other lesions can be formed in lipid bilayers by various small molecules, including pore-forming protein toxins (61), highly charged synthetic nanoparticles (62)(63)(64)(65)(66), and polycationic polymers (67)(68)(69)(70)(71). Hole formation in each case is dependent upon the specific interactions between the membrane and the disruptive molecule of interest.…”

Scanning Probe Microscopy of Nanocomposite Membranes and Dynamic Organization

“…Also, high‐resolution AFM images demonstrated that membrane defects were also formed inside the nanorings 58. The nature of the reorganization was investigated and it could be explained by a mechanism involving both metal coordination and the previously described pH effects of membrane reorganization and disruption 26, 58. In brief, the Zr metal allowed for coordination of COOH groups on the Au NPs.…”

“…The observation was the same for both positively and negatively charged particles, indicating that all particle collisions are elastic in the absence of electrostatic attractions and with substrate support. The other interactions, such as hydrogen bonding, are not strong enough to bring the particle close enough to the LBA or eliminate the hydration layers of water around the hydrophilic lipid headgroups 57–59…”

“…As shown in Figure A, each individual spot represents single AuNPs or their aggregates adsorbed on a DOTAP LBA. The distribution of particles was rather random but coverage was complete 58…”

“…E) Schematics of the interactions between a partially negatively charged nanoparticle and a positively charged bilayer with increased local charge density and fluidic phase domain size (left to right). Figure adapted with permission 58, 59. Copyright 2011 and 2012, American Chemical Society.…”