title: Sequence, structure, and function of peptide self-assembled monolayers.
abstract: Cysteine is commonly used to attach peptides onto gold surfaces. Here we show that the inclusion of an additional linker with a length of four residues (-PPPPC) and a rigid, hydrophobic nature is a better choice for forming peptide self-assembled monolayers (SAMs) with a well-ordered structure and high surface density. We compared the structure and function of the nonfouling peptide EKEKEKE-PPPPC-Am with EKEKEKE-C-Am. Circular dichroism, attenuated total internal reflection Fourier transform IR spectroscopy, and molecular dynamics results showed that EKEKEKE-PPPPC-Am forms a secondary structure while EKEKEKE-C-Am has a random structure. Surface plasmon resonance sensor results showed that protein adsorption on EKEKEKE-PPPPC-Am/gold is very low with small variation while protein adsorption on EKEKEKE-C-Am/gold is high with large variation. X-ray photoelectron spectroscopy results showed that both peptides have strong gold-thiol binding with the gold surface, indicating that their difference in protein adsorption is due to their assembled structures. Further experimental and simulation studies were performed to show that -PPPPC is a better linker than -PC, -PPC, and -PPPC. Finally, we extended EKEKEKE-PPPPC-Am with the cell-binding sequence RGD and demonstrated control over specific versus nonspecific cell adhesion without using poly(ethylene glycol). Adding a functional peptide to the nonfouling EK sequence avoids complex chemistries that are used for its connection to synthetic materials.
authors.affiliation: Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Ann K
authors.initials: AK
authors.lastname: Nowinski
authors.forename: Fang
authors.initials: F
authors.lastname: Sun
authors.forename: Andrew D
authors.initials: AD
authors.lastname: White
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Keefe
authors.forename: Shaoyi
authors.initials: S
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D057219:Biofouling; D006046:Gold / Q000737:chemistry; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012996:Solutions; D013499:Surface Properties
chemical_list: D009842:Oligopeptides; D012996:Solutions; D006046:Gold