Preparation of bioactive surface via gel oxidation on titanium for biomedical application (hip joint replacement)

Titanium and its alloys are widely used as implant in biomedical applications. They have good mechanical and chemical properties, biocompatibility and biointegration with human body, but they have no ability to bond directly to natural bone. Therefore, alkali and heat treatments (gel oxidation) were introduced to improve the bioactivity of titanium by forming a mixture of sodium titanate and rutile on the surface of titanium. This method enables titanium to possess a bioactive surface which is essential to induce the apatite formation. This study aims to investigate the effects of alkali, sodium removal and heat treatments on in vitro bioactivity of titanium. UV light irradiation was used to study the effect on in vitro bioactivity of titanium. Alkalitreated titanium subjected to heat treatment in air have shown better overall in vitro performance than those treated in argon atmosphere. Therefore, the sodium removal treatment (dilute hydrochloric acid (HCl) treatment) was introduced to convert sodium titanate into anatase to improve the bioactivity of titanium treated in argon atmosphere. Thus, four samples (AT-0.5-HT500R, AT-0.5-HT600R, AT-5-HT500R and AT-5- HT600R) with different ratios of anatase to rutile were produced by varying the concentration of HCl acid treatment and heating temperature in argon atmosphere. It was found that the incorporation of sodium removal treatment has reduced two times the duration of apatite formation as compared with the conventional alkali and heat treatments. In order to further enhance the bioactivity, these samples were subjected to six different conditions of ultraviolet light irradiation and followed by in vitro bioactivity test. As a result, AT-5-HT500R (82.2% anatase and 17.8% rutile) was proven to deliver the best performance. It was confirmed that UV light irradiation enhances the bioactivity by removing hydrocarbon, inducing superhydrophilicity and forming OH groups. It was discovered that the duration of apatite formation was shortened to 7 days. Furthermore, the continuous UVA irradiation during in vitro test resulted in the acceleration of bonelike apatite formation in 3 days. It can be concluded that the sodium removal treatment and UV light irradiation give very significant impact to the formation of bonelike apatite on the titanium surfaces for biomedical applications.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

Universiti Tun Hussein Onn Malaysia

Year dc:date.issued

2018

Author dc:creator

• Tan, Kwok Joon

• TN600-799 Metallurgy

Language dc:language

en