SBIR-STTR Award

Poor adhesion is the single most severe problem related to the long term viability of implantable hydroxyapatite coatings. An innovative room temperature electrophoretic process is proposed to fabricate nanostructured hydroxyapatite ("n"-HAP) coatings, eliminating problems related to amorphous phase formation and delamination. To date, only micron-sized hydroxyapatite materials have been deposited using electrophoresis. The n-HAP coating will exhibit increased toughness, bond strength, and a high degree of crystallinity. The nature of the bond is metallurgical, resulting in dramatically improved bond strength when compared to mechanical bonds obtained in thermal spray coatings. Electrophoresis also enables multicomponent codeposition. This program consists of (1) synthesizing n-HAP particles, (2) depositing the n-HAP coating, and (3) coating evaluation. while the n-HAP is expected to yield a several4old increase in bond strength, a calcium phosphate cement (CPC) additive will be cc-deposited with the n-HAP to further increase bond strength. A dense graded TiO2 bond coat will be introduced (a few microns thick) between the n-HAP and the titanium substrate in the deposition process, so that body fluids will have no opportunity to attack and degrade the titanium. Inframat is collaborating with Dr. Antoni Tomsia of the Lawrence Berkeley National Lab to evaluate the nanostructured coatings. PROPOSED COMMERCIAL APPLICATIONS: Potential commercial applications include advanced coated implants for hips, knees, and other prostheses in humans and animals. In the US alone,the annual number of hip and knee operations using HAP coated implants is estimated to already produce an annual revenue of $3 billion. With the increasing age of the larger population, the estimated demand for implants will rise significantly in the near future. A comparable European market doubles the potential revenue

This proposed phase II program is expected to produce prototype hydroxyapatite ("HA") coated bone implants with significantly extended lifetime, fabricated using a room temperature electrophoretic deposition process. Novel HA nanocoatings with significantly increased adhesion strength and corrosion resistance under simulated body fluid in-vitro have been demonstrated in the Phase I work. The proposed Phase II program emphasizes developing prototype implant devices to rapidly commercialize this Phase I nanotechnology. The benefits of exceptional coating to substrate bond strength enable expansion of the HA nanocoatings market to hips, knees, and dental applications. Achieving 100% crystallinity and density at the HA substrate interface with electrophoretic deposited HA nanocoatings assures no degradation during implant service. Functionally graded HA nanocoatings can be generated at the HA tissue interface, thus promoting optimal bioactivity. The Phase II specific aims include scale up of the experimental HA bath nanocoating composition to pilot-scale production of prototype medical implants; demonstration of the HA nanoparticles coating on prototype medical implants, such as hip, knee, and dental implants; and demonstration of superior performance of the coated prototype devices with extended lifetime in-vivo, using an animal model. Phase II participants include Spire Corporation and the University of Texas at San Antonio.

Thesaurus Terms:
adhesion, biomaterial development /preparation, bone prosthesis, electrophoresis, hydroxyapatite, surface coating biological model, biomaterial interface interaction, cell differentiation, cell proliferation, corrosion, dental implant, joint prosthesis, osteoblast dog, medical implant science, nanotechnology