title: Anisotropic metal growth on phospholipid nanodiscs via lipid bilayer expansion.
abstract: Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the "outer shape" of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of ~10 nm diameter containing a lipid bilayer ~5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials.
authors.affiliation: Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, P.O.B. 510119, 01314 Dresden, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Oertel
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O.B. 510119, 01314 Dresden, Germany.|Technical and Macromolecular Chemistry, University of Paderborn, Warburger Str. 100, 33098 Paderborn, Germany.
authors.forename: Adrian
authors.initials: A
authors.lastname: Keller
authors.affiliation: Department of Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Prinz
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O.B. 510119, 01314 Dresden, Germany.|Technische Universität Dresden, Mommsenstraße 13, 01069 Dresden, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schreiber
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O.B. 510119, 01314 Dresden, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Hübner
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O.B. 510119, 01314 Dresden, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Kerbusch
authors.affiliation: Department of Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany.|BAM Federal Institute of Materials Research and Testing, Richard-Willstätter Strasse 11, 12489 Berlin, Germany.
authors.forename: Ilko
authors.initials: I
authors.lastname: Bald
authors.affiliation: Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, P.O.B. 510119, 01314 Dresden, Germany.|Technische Universität Dresden, Mommsenstraße 13, 01069 Dresden, Germany.
authors.forename: Karim
authors.initials: K
authors.lastname: Fahmy
mesh_terms: D016880:Anisotropy; D006046:Gold / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D010743:Phospholipids; D006046:Gold