Characterization of the substructure and properties of immobilized peptides on silicon surface

Immobilization of biomaterials onto solid supports is a means of functionalizing materials for applications such as biosensing. Biologically active peptide (A-A-A-A-G-G-G-E-R-G-D) films were attached to N-hydroxy succinimide ester terminated self-assembled monolayers (SAM) which were covalently linked to a smooth silicon surface via Si–C bonds. The peptide films were characterized using electrical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The film structures were determined from examination of the capacitance and conductance dispersions with frequency. Analysis of XPS, EIS and FTIR after immobilization of the peptide film at pH 4 and 7 provided information on the extent of the activation and overall coupling efficiencies of the peptides to the N-hydroxy succinimide ester surface. The resulting film structure was markedly altered by attachment of the peptide at pH 4.