Characterization of peptide immobilization on an acetylene terminated surface via click chemistry

Peptide (A-A-A-A-G-G-G-E-R-G-D)(1) conjugated surfaces were prepared on silicon surfaces through click chemistry. The amino acid sequence RGD is the cellular attachment site of a large number of extracellular matrices such as blood and cell surface proteins. Recent research has focused on developing RGD peptides which mimic cell adhesion proteins and integrins [1.2]. The steps involved the formation of an alkyne-terminated monolayer on Si(111), followed by linking the peptide to 4-azidophenyl isothiocyanate via a specific and gentle reaction. This was followed by the attachment of the azido peptide to the surface-bound alkynes using the Cu (I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction. The surface structures of the alkyne terminated monolayer and the attached peptide were characterized using high resolution impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared (ATR-FTIR) Spectroscopy. EIS characterization revealed the alkyne layer and the hydrophobic and polar regions of the attached peptide. XPS analysis showed a high surface coverage of the peptide on the silicon substrates and this was confirmed by FTIR. Our results confirmed a specific covalent attachment of the peptide on the silicon surfaces. This approach offers a versatile, experimentally simple, method for the specific attachment of peptide ligands. This approach would have applications for cell attachment and biosensors. (C) 2011 Elsevier B.V. All rights reserved.