AVS 59th Annual International Symposium and Exhibition
    Biomaterial Interfaces Tuesday Sessions
       Session BI+AS-TuA

Paper BI+AS-TuA4
Adsorption Behavior of Serum Albumin on Nanocrystalline Apatites

Tuesday, October 30, 2012, 3:00 pm, Room 23

Session: Characterization of Biointerfaces
Presenter: K. Fears, U.S. Naval Research Laboratory
Authors: K. Fears, U.S. Naval Research Laboratory
D. Burden, U.S. Naval Research Laboratory
C. Love, U.S. Naval Research Laboratory
D. Day, Missouri University of Science and Technology
T. Clark, U.S. Naval Research Laboratory
Correspondent: Click to Email
The adsorption behavior of bovine serum albumin (BSA) on nano-crystalline hydroxyapatite (HA) and strontium apatite (SrHA) microspheres, derived from borate glasses, was assessed using circular-dichroism spectroscopy (ECD). Numerous reports have shown that surfaces which present nano-sized features can exhibit better cellular response than surfaces with features in the micron regime. The microspheres were incubated in BSA solutions (40 mg/mL; ~64% helix; ~1% sheet) to determine if BSA adsorbed in a fundamentally different manner than on bioinert yttria-alumina-silicate (YAS) spheres that induced minimal conformational changes (~56% helix; ~4% sheet). On the apatite spheres, BSA loss a substantial amount of its helical structure and strained disulfide bonds were detected. However, the protein density on the SrHA spheres was 50% lower than on the HA spheres, indicating that BSA has a higher affinity for irreversible adsorption on HA. 5,5'-Dithio-bis-(2-nitrobenzoic acid), was used to selectively modify free thiols post-adsorption, indicating that solvent-accessible free cysteines were present on the apatite spheres, despite the absence of a reducing agent. Subsequent BSA molecules, or other proteins in vivo, could potentially form intermolecular disulfide bonds leading to increased adhesion of proteins or support the formation of macroscopic protein structures.