title: Effects of gold nanoparticles on lipid packing and membrane pore formation.
abstract: Gold nanoparticles (AuNPs) have been increasingly integrated in biological systems, making it imperative to understand their interactions with cell membranes, the first barriers to be crossed to enter cells. Herein, liposomes composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) as a model membrane system were treated with citrate stabilized AuNPs from 5 to 30 nm at various concentrations. The fluorescence shifts of Laurdan probes reveal that AuNPs in general made liposomes more fluidic. The increased fluidity is expected to result in an increased surface area, and thus liposome shape changes from circular to less circular, which was further confirmed with fluorescence microscopy. The localized stress in lipids induced by electrostatically adsorbed AuNPs was hypothesized to cause the dominant long-range effect of fluidization of unbound lipid membranes. A secondary effect of the AuNP-induced lateral pressure is the membrane rupture or formation of pores, which was probed by AFM under fluid. We found in this study a nanoparticle-mediated approach of modulating the stiffness of lipid membranes: by adsorption of AuNPs, lipids at the binding sites are stiffened whereas lipids afar are fluidized. Understanding the factors that modulate lipid packing is important for the discovery of alternative therapeutic methods for diseases linked to membrane integrity such as high blood pressure and cancer metastasis.
authors.affiliation: Department of Physics and Engineering, Delaware State University , Dover, Delaware 19901, USA.
authors.forename: Anupama
authors.initials: A
authors.lastname: Bhat
authors.affiliation: Department of Biological Sciences, Delaware State University , Dover, Delaware 19901, USA.
authors.forename: Lance W
authors.initials: LW
authors.lastname: Edwards
authors.forename: Xiao
authors.initials: X
authors.lastname: Fu
authors.affiliation: Department of Physics and Engineering, Delaware State University , Dover, Delaware 19901, USA.
authors.forename: Dillon L
authors.identifier: 0000-0002-1085-4216
authors.initials: DL
authors.lastname: Badman
authors.affiliation: Wilmington Friends School , Wilmington, Delaware 19803, USA.
authors.forename: Samuel
authors.initials: S
authors.lastname: Huo
authors.affiliation: National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health , Bethesda, Maryland 20892, USA.
authors.forename: Albert J
authors.identifier: 0000-0003-3826-1081
authors.initials: AJ
authors.lastname: Jin
authors.affiliation: Department of Physics and Engineering, Delaware State University , Dover, Delaware 19901, USA.
authors.forename: Qi
authors.identifier: 0000-0002-1725-5398
authors.initials: Q
authors.lastname: Lu