Fabrication And Bioloaical Characteriza--tion Of HA/ZnO-nanorods Composite Coating

Researches on metallic implants surface modification using bioactive coatings is one of the most attractive aspects of biomaterials. Bioactive coatings should be able to modulate materials/cell interfical reactions at the molecular level and initiatively stimulate cell activity to promote osteointegration. Hydroxyapatite (HA) coating has been widely used to improve implant/bone tissue bonding. However, the clinical application of HA coatings shows limited cell-coating interaction and slow osteointegration in the early stage. In this dissertation, based on the interface reactions between implant and bone, an approach of bioactive functional coatings with micro-nano structure was proposed.Micro-nano composite coatings with hydrophobic and hydrophilic domains, as well as zinc ions release ability, were prepared. Firstly, ZnO nanorods were grown on substrates through hydrothermal process. Then, several methods were attempted to realize the selective growth of ZnO nanorods. Based on the results, we fabricated HA/ZnO-nanorods composite coatings and HA/selective-grown-ZnO-nanorods composite coatings through sol-gel methods. These coatings showed excellent cytocompatibility. Accordingly, the main work and main results are summarized as followings:1. Ordered and uniform ZnO nanorods were prepared through low-temperature hydrothermal growth of pre-formed ZnO films on substrates. Wettability of such surface could be switched by UV irradiation.2. Selective growth of ZnO nanorods were realized through spin-coating ZnO microdots, depositing atomized seeding solution, porous templates and PDMS seals. ZnO regions could be controlled by adjusting porous templates.3. HA/ZnO-nanorods composite coatings were fabricated by sol-gel methods on ZnO nanorods surface. The coating surface is photo-responsible with HA wrapping ZnO nanorods structure. Zinc release ability of the coating is slow and sustained in the safe concentration range. Protein adsorption profile showed the coating is amphiphilic, moreover, its adsorption ability could be improved though a simple UV irradiation.4. HA/selective-grown-ZnO-nanorods composite coatings were prepared on selective grown ZnO nanorods surface with HA/ZnO-nanorods region and surrounded HA. The coating not only remains amphiphilic on protein adsorption, but may also adjust the distribution of proteins, thus demonstrated stimulation for cell attachment and proliferation in vitro.