AVS 50th International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuP

Paper BI-TuP10
Chemisorption of Aromatic Amino Acid Derivatives on Gold Surface

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: R.M. Petoral, Jr., Linköping University, Sweden
Authors: R.M. Petoral, Jr., Linköping University, Sweden
K. Uvdal, Linköping University, Sweden
Correspondent: Click to Email
The interfacial property of adsorbate and thin layers of biomolecules on solid surfaces is of great significance in biomaterials and biosensor application. Understanding the binding and molecular orientation of the adsorbates is then of great importance. Amino acids with aromatic side chains such as Tyrosine and 3,4-dihydroxyphenylalanine (DOPA) is linked to a short thiol through a peptide bond and is adsorbed and self-assembled to polycrystalline gold surfaces. The molecular adsorption, chemical binding and orientation of the amino acid analogue to the surface are studied by X-ray Photoelectron Spectroscopy (XPS), Infrared Reflection-Absorption Spectroscopy (IRAS) and Near-edge X-ray Absorption Fine Structures (NEXAFS). Strong molecular binding of the amino acid derivatives on gold surface through the sulfur atom was attained. Angle dependent XPS results showed that the aromatic ring is oriented away from the gold surface. Parallel orientation of the C=O bond of the amide moiety relative to the gold surface is deduced from the IRAS and NEXAFS results. The average orientation of the aromatic ring and main molecular axis of the molecules relative to the gold surface are also determined. The aromatic amino acid derivatives are able to self-assemble and form an ordered monolayer with minimal degree of orientational disorder. Results from this experiment are valuable in our development of sensor surfaces to be used for interaction studies with other biomolecules and metal ions.