4, University of California, Riverside, Riverside, California, United States
3, N2 Biomedical LLLC, Bedford, Massachusetts, United States
2, University of California, Riverside, Riverside, California, United States
Magnesium (Mg) and its alloys have showed a promising potential for medical implant applications due to their attractive biocompatibility and mechanical strength properties. Despite these promising properties, the critical challenge with Mg-based implants is rapid degradation in physiological environment that results in early loss of mechanical strength and hydrogen gas accumulation at the local site. Hydroxyapatite (HA) coatings provide a sound solution for controlling Mg degradation at the bone interface. In this paper, HA coatings with different particle sizes, namely, microHA (mHA) and nanoHA (nHA), were deposited on Mg discs and rods with two different pressures using N2 Biomedical’s proprietary deposition process called IonTiteTM. The degradation property of HA coated Mg prepared by IonTiteTM was studied in revised simulated body fluid (rSBF) for six weeks. Both mHA and nHA coatings have showed reduction of degradation rates and maintained the mechanical integrity of Mg during the 6-week immersion study in rSBF. The mHA samples deposited at high pressure (mHA_400) showed a slower corrosion rate among all group of samples. The effects of geometry (disc versus rod) on degradation rate were also investigated and HA coated Mg rods showed a slower degradation rate compared to HA coated Mg discs. In this study, we have demonstrated that HA coated Mg substrates are promising materials as bioresorabable implants for orthopedic and craniofacial applications, and confirmed the optimal IonTiteTM process conditions that could produce HA coatings on Mg with superior degradation performance.