title: Molecularly resolved images of peptide-functionalized gold surfaces by scanning tunneling microscopy.
abstract: Peptide-terminated monolayers were formed through a Huisgen cycloaddition reaction between an α-helical peptide containing two propargylglycine unnatural functional groups 20 Å apart and an alkanethiol self-assembled monolayer (SAM) on a gold surface containing 25% surface density of reactive azide terminal groups. The azide- and peptide-terminated surfaces were imaged by scanning tunneling microscopy (STM) using a low tunneling current of 10 pA. On the peptide-terminated surface, oblong features ~30 Å long and ~20 Å wide were observed and attributed to individual surface-bound α-helical peptides oriented parallel to the gold surface. These features covered an area of the surface corresponding to a density of 0.11 ± 0.01 peptides nm(-2), compared with a theoretical density of ~0.14 peptides nm(-2) for a fully reacted surface. Finally, no evidence of peptide aggregation was observed on either short (<10 nm) or long (~100 nm) length scales.
authors.affiliation: Department of Chemistry and Biochemistry, Center for Nano- and Molecular Science and Technology, and Institute for Cell and Molecular Biology, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, USA.
authors.forename: Annette F
authors.initials: AF
authors.lastname: Raigoza
authors.forename: Lauren J
authors.initials: LJ
authors.lastname: Webb
mesh_terms: D006046:Gold / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling; D057054:Molecular Imaging; D010455:Peptides / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D010455:Peptides; D006046:Gold