Synthesis and Characterization of Ti-6Al-4V Coated with Hydroxyapatite-Gelatin as A Bone Implant

Abstract

Titanium and its alloys have been widely used as bone implants. However, metals have poor adhesion properties and low corrosion resistance, so a coating with biocompatible materials such as hydroxyapatite (HAp) is required. HAp must have a small pore size before coating, thus requiring gelatin to reduce the pore size. Therefore, the aim of this study is to coat HAp-gelatin on Ti-6Al-4V metal alloy using a modified dip-coating method and characterize its properties. The 30% HAp-gelatin composite synthesized by the in-situ method can be coated on the Ti-6Al-4V metal alloy using a modified dip-coating method, which involves an immersion for one week. Before coating, the Ti-6Al-4V metal was cut into round pieces with a diameter of 1.3 cm and a thickness of 3 mm. Then the metal is polished, washed with ethanol and then distilled water. After that, the metal is soaked in a NaOH solution followed by rinsing with an distilled water. The resulting Ti-6Al-4V-HAp-gelatin implant has better corrosion resistance properties than uncoated Ti-6Al-4V metal, as its corrosion rate decreases from 0.4152 mpy to 0.2369 mpy. Ti-6Al-4V-HAp-gelatin has good mechanical strength as it only experiences a decrease in hardness of 0.67% after coating. Implants can also stimulate mineralization in the bone through the release of Ca²⁺ ions and the deposition can be seen from the decrease in the concentration of dissolved ions up to 98.65%. The results of the analysis of X-ray diffraction patterns on Ti-6Al-4V-HAp-gelatin showed the HAp and Ti phases. Infrared spectral analysis showed the presence of hydroxyl and phosphate functional groups derived from HAp, carbonyl from gelatin, and carbonate groups derived from CaCO3 that were still left in the sample. Scanning of electrons reveals the morphology of Ti-6Al-4V-HAp-gelatin in the form of granules and varies in size due to its amorphous phase. As a suggestion for further research, it is necessary to further test the HAp-gelatin coating method on Ti-6Al-4V metal to achieve better adhesion.