The Study of Strontium-Substituted Hydroxyapatite Coating on Titanium by Electrolytic Deposition

• Main Authors: Han-LinChang, 張翰林
• Other Authors: Ching-Cheng Wang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/89906712418299593613

碩士 === 國立成功大學 === 製造資訊與系統研究所碩博士班 === 101 === Hydroxyapatite (HA) is widely used as bioactive coating material and easily incorporated a variety of substituents in the apatite structure. The substitution of strontium (Sr) ions has been widely researched in recent years. Because strontium has irreplaceable characteristics , and promotes osseointegration and reduces bone resorption. The electrolytic deposition technique is a simple, easy controlled, low cost and one-step process method. The application of an electric field can deposit inorganic irons on the conductive substrate surface. In this study, the strontium-substituted hydroxyapatite (Sr-HA) is electrochemically deposited onto the titanium (Ti) substrate using a modulated electrical potential and electrolyte composition. It is divided into three parts in this study, the investigation of electrolytic deposition parameters, the coating analysis of material properties , and the coating analysis of the in vitro test, respectively. In part one, it shows that the reaction temperature and the phase of coating are related ; the current density and the uniform of coating are related ; also the reaction time and the thickness of coating are related. In part two, it indicates that suitable parameters in part one can deposite at various strontium concentration coatings with uniform, high crystallization and purity.The SEM results indicated that the flat structure of coating was transferred to needle-like and dense structure with raising strontium content. Notably, the corresponding strontium signal was detected by the EDS and ICP-AES. The rate of Sr substitution was 94.5% and the rate of (Ca+Sr)/P was between 1.6 and 1.69. The XRD analysis indicated that the phase of coating was Sr-HA and Ti. These results confirmed that strontium, calcium and phosphate were coated onto the titanium surface and major composed by Sr-HA. After heat treatment at 700oC for one hour, the crystallization of HA increased. Scratch test showed that the critical load is two times greater than one without heat treatment. The immersion test showed that the coating can absorb Ca32+ and PO43- to form an apatite onto surface. However, the coating could restrain the release of Sr after heat treatment. The immunofluorescence test and cell observation showed that the initial unmbers and adherence in MC3T3-E1 cells with heat treatment are greater than ones without heat treatment , and they become better with the gain of Sr concentration. In this study, it can produce the various concentration of Sr-HA coatings onto the Ti substrate with high crystallization and purity using the electrolytic deposition method. After heat treatment, it can enhance the bioactive and the strength of interface. Therefore, it is expected to be applied to manufacture and modification of dental implant in the future.