title: Surface-enhanced Raman scattering measurement from a lipid bilayer encapsulating a single decahedral nanoparticle mediated by an optical trap.
abstract: We present a new technique for the study of model membranes on the length-scale of a single nano-sized liposome. Silver decahedral nanoparticles have been encapsulated by a model unilamellar lipid bilayer creating nano-sized lipid vesicles. The metal core has two roles (i) increasing the polarizability of vesicles, enabling a single vesicle to be isolated and confined in an optical trap, and (ii) enhancing Raman scattering from the bilayer, via the high surface-plasmon field at the sharp vertices of the decahedral particles. Combined this has allowed us to measure a Raman fingerprint from a single vesicle of 50 nm-diameter, containing just ∼104lipid molecules in a bilayer membrane over a surface area of <0.01 μm2, equivalent to a volume of approximately 1 zepto-litre. Raman scattering is a weak and inefficient process and previous studies have required either a substantially larger bilayer area in order to obtain a detectable signal, or the tagging of lipid molecules with a chromophore to provide an indirect probe of the bilayer. Our approach is fully label-free and bio-compatible and, in the future, it will enable much more localized studies of the heterogeneous structure of lipid bilayers and of membrane-bound components than is currently possible.
authors.affiliation: Department of Electrical and Electronic Engineering, University of Nottingham, Nottingham, NG7 2RD, UK. amanda.wright@nottingham.ac.uk.
authors.forename: A J
authors.identifier: http://orcid.org/0000-0002-4866-5699
authors.initials: AJ
authors.lastname: Wright
authors.affiliation: Faculty of Pharmaceutical Sciences, 2405 Wesbrook Mall, Vancouver, BC Canada, V6T 1Z3.
authors.forename: J L
authors.initials: JL
authors.lastname: Richens
authors.affiliation: Faculty of Pharmaceutical Sciences, 2405 Wesbrook Mall, Vancouver, BC Canada, V6T 1Z3.
authors.forename: J P
authors.initials: JP
authors.lastname: Bramble
authors.affiliation: Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Cathcart
authors.affiliation: Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Kitaev
authors.affiliation: Faculty of Pharmaceutical Sciences, 2405 Wesbrook Mall, Vancouver, BC Canada, V6T 1Z3.
authors.forename: P
authors.initials: P
authors.lastname: O'Shea
authors.affiliation: Department of Chemistry, University of Leicester, Leicester, LE1 7RH, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Hudson
mesh_terms: D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D053758:Nanoparticles; D052898:Optical Tweezers; D013059:Spectrum Analysis, Raman
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes