Fabrication of function-switchable surfaces in metallic biomaterials

羟基磷灰石（HAp）在模拟体液（SBF）中会在生物活性材料上沉淀。研究了紫外光照射下羟基磷灰石（HAp）在TiO 2和ZrO 2表面的形成。HAp在ZrO 2表面上的形成对热处理和UV照射不敏感。与此相反，HAp的形成上的TiO 2在SBF的强烈影响热处理和紫外线照射。热处理可以降低TiO 2表面的羟基密度。然后通过先前的UV照射可以恢复密度，这导致促进HAp的形成。这意味着TiO 2表面上的生物活性恢复。紫外光在TiO 2中产生电子-空穴对，迁移到表面的光生空穴排斥溶液中的带正电荷的离子。因此，连续的UV照射抑制了HAp的形成。这些结果表明，在TiO 2的几个功能可能会被光照射切换。

Hydroxyapatite (HAp) is known to precipitate on bioactive materials by soaking in simulated body fluid (SBF). The formation of HAp on TiO2 and ZrO2 surfaces under ultraviolet (UV) irradiation was investigated. HAp formation on ZrO2 surface was not sensitive to heat treatment and UV irradiation. In contrast, the HAp formation on the TiO2 in SBF was strongly influenced by heat treatments and UV irradiation. Hydroxyl group density on TiO2 surface could be decreased by the heat treatment. Then the density could be recovered by previous UV irradiation, it led to promotion of HAp formation. This means recovery of bioactivity on the TiO2 surface. The UV light produced electron-hole pairs in the TiO2, and the photogenerated holes that migrated to the surface repelled the positively charged ions in the solution. As a consequence, the continuous UV irradiation suppressed the formation of HAp. These results suggest that several functions in TiO2 might be switched by light irradiation.