title: Structural control of peptide-coated gold nanoparticle assemblies by the conformational transition of surface peptides.
abstract: Gold nanoparticles having peptide chains on the surfaces have been prepared yb ring-opening polymerization of gamma-methyl L-glutamate N-carboxyanhydride with fixed amino groups on the nanoparticle surface as an initiator. The number of peptide chains on the surface was adjusted to ca. 2 molecules per gold nanoparticle by controlling the number of fixed amino groups on the surface. The peptide chains on the surface were partially saponified to obtain poly(gamma-methyl L-glutamate-co-L-glutamic acid) with 28 mol% of glutamic acid residues. The number-average molecular weight of the peptide was 73,000. We described structural control of the peptide-coated gold nanoparticle assembly by conformational transition of the surface peptides. In deionized water, the peptide chains on the nanoparticle took a random coil conformation, and the individual nanoparticles existed in dispersed globular species. On the other hand, the peptide chains on the nanoparticle took an alpha-helical conformation in trifluoroethanol. Under this condition, the alpha-helical peptide chains on distinct gold nanoparticles connected the nanoparticles to form a fibril assembly owing to the dipole-dipole interaction between the surface peptide chains. The morphology of the peptide-coated gold nanoparticle assembly could be controlled by the conformational transition of surface peptides, which was attended by solution composition changes.
authors.affiliation: Department of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurimanakayama-Cho, Tsu, Mie 514-8507, Japan. higuchi@chem.mie-u.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Higuchi
authors.forename: Kae
authors.initials: K
authors.lastname: Ushiba
authors.forename: Masami
authors.initials: M
authors.lastname: Kawaguchi
mesh_terms: D002942:Circular Dichroism; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles; D018625:Microscopy, Atomic Force; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D010455:Peptides; D006046:Gold