Characterization of Peptide Adsorption on InAs Using X-ray Photoelectron Spectroscopy
Date of this Version4-5-2011
Langmuir, 2011, 27 (7), pp 3774–3782
The well-defined structure and high stability of peptides make them attractive biotemplates for low-temperature synthesis of semiconductor nanocrystals. Adsorbed peptide monolayers could also potentially passivate semiconductors by preventing regrowth of the oxide layer. In this work, the adsorption and passivation capabilities of different collagen-binding peptides on In As surfaces were analyzed by X-ray photoelectron spectroscopy (XPS). Before peptide functionalization, Br(2)- and HCl-based etches were used to remove the native oxide layer on the In As surfaces. The presence of the N is peak for peptide-functionalized samples confirms the adsorption of peptides onto the etched In As surfaces. Calculated coverages were similar for all peptide sequences and ranged from similar to 20 to 40% of a monolayer using the deconvoluted C Is spectra and from similar to 2 to 5% for the N Is spectra. The passivation ability of the peptides was analyzed by comparing the ratios of the oxide components to the nonoxide components in the XPS spectra. The thickness of the oxide layer was also approximated by accounting for the attenuation of the substrate photoelectrons through the oxide layer. We find that the oxide layer regrowth still occurs after peptide functionalization. However, the oxide layer thicknesses for peptide-functionalized samples do not reach as received levels, indicating that the peptides do have some passivation ability on InAs.
Nanoscience and Nanotechnology