Assessment of novel chemical strategies for covalent attachment ofadhesive peptides to rough titanium surfaces: XPS analysis andbiological evaluation

Bioactive molecules have been proposed to promote beneficialinteractions at bone-implant interfaces for enhancing integration. Themain objective of this study was to develop novel methods tofunctionalize oxidized titanium surfaces by the covalent immobilizationof bioactive peptides, through selective reaction involving singlefunctional groups. In the first protocol, an aminoalkylsilane wascovalently linked to the Ti oxide layer, followed by covalent bindingof glutaric anhydride to the free NH2 groups. The carboxylic group Ofglutaric anhydride was used to condense the free N-terminal group ofthe side-chain protected peptide sequence. Finally, the Surface wastreated with trifluoroacetic acid to deprotect side-chain groups. Inthe second protocol, the peptide was directly anchored to the Ti oxidesurface via UV activation of an arylazide peptide analogue. X-rayphotoelectron spectroscopy analyses confirmed that modificationsinduced onto surface composition were in agreement with the reactionsperformed. The peptide density of each biomimetic Surface wasdetermined on the basis of radiolabeling and XPS derived reactionyields. The in vitro cellular response of the biomimetic surfaces wasevaluated using a primary human osteoblast cell model. Cell adhesion,proliferation, differentiation, and mineralization were examined atinitial-, short-, and long-time periods. In was shown that thebiomimetic surface obtained through photoprobe-marked analogue thatcombines an easily-performed modification provides a favorable surfacefor an enhanced cellular response. (C) 2008 Wiley Periodicals, Inc. JBiomed Mater Res 91A: 463-479, 200