AVS 52nd International Symposium
    Biomaterial Interfaces Monday Sessions
       Session BI-MoP

Paper BI-MoP17
Studies of Protein Interactions with CaP Surfaces Using XPS and ToF-SIMS

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Biomaterial Interfaces Poster Session
Presenter: D.G. Castner, University of Washington
Authors: C. Mendoza-Barrera, University of Washington
H.E. Canavan, University of Washington
R. Michel, University of Washington
D.G. Castner, University of Washington
Correspondent: Click to Email
Proteins directly control the nucleation and growth of biominerals, but the details of molecular recognition at the protein-biomineral interface remain poorly understood. The elucidation of recognition mechanisms at this interface may provide design principles for advanced materials development in bone replacement. In this work, we characterize the interactions of proteins with the principal calcium phosphate components of bone. Using X-ray diffraction (XRD), we characterized the purity and phases of hydroxyapatite (HAp), dibasic calcium phosphate dihydrate (DCPD), dibasic calcium phosphate (DCP), @beta@ tribasic calcium phosphate (@beta@-TCP) and monbasic calcium phosphate (MCP). Next, adsorption isotherms of different proteins (e.g. BSA and fibrinogen) were performed on each calcium phosphate substrate. In this way, the solution concentrations necessary to produce sub-monolayer and monolayer thicknesses of each protei n was determined via X-ray photoelectron spectroscopy (XPS). As the conformation of proteins is greatly influenced by their density on a surface, we next used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to compare the comformation of different protein layers adsorbed on the different calcium phosphate substrates. Finally, we discuss the effect of protein identity, conformation, and the character of the calcium phosphate substrate have on protein adsorption.