Chin-shih Hsu1 Qizhen Li1

1, Washington State University, Pullman, Washington, United States

In the process of bone formation, osteoclast and osteoblast cells are two critical roles. The slight acidity induced in vivo by substituted chlorine in hydroxyapatite (ClHAp) stimulates osteoclasts for the process of bone resorption. However, no studies disclose the osteoblastic cell activity on ClHAp. The present study aims to improve the mechanical and biological properties of hydroxyapatite (HA)/polydopamine (DPA) coating on Ti64, and sintered HA bioceramics through chlorine substitution into HA.
The ph value induced by ClHAp/DPA coating on Ti64 in simulated body fluid (SBF) slightly increases from 7.4 to about 7.45 after day 1 and decreases slowly to 7 ~ 7.1 for 1 week. The release rate of chloride from the coating will be analyzed.
A higher ratio of substituted chlorine causes a greater relative density, surface hardness, compressive strength and better hydrophilicity of ClHA bioceramics. The ph value induced by ClHA bioceramics in SBF decreases from 7.4 to about 7.1 ~ 7.2 after immersion for 9 days. A slower release rate can be observed after immersion into SBF for 7 days.
Both the ClHAp/DPA coating on Ti64 and the sintered ClHAp bioceramics will undergo the tests of osteoblastic cell viability to find the optimal ratio of substituted chlorine.