Physicochemical Characterization and Antibacterial Activity of Titanium/Shellac-Coated Hydroxyapatite Composites

Abstract

Titanium and hydroxyapatite are widely used as materials for implants. Titanium has good mechanical properties, good corrosion resistance, and a high modulus of elasticity. Hydroxyapatite has good biocompatibility, bioactivity, and significant osteoinductivity. In this study, powder metallurgy was used as a method to combine titanium and hydroxyapatite for use in implants. Shellac was used as a binder between ceramic and metal due to its lower melting point. The surface morphology and chemical properties were evaluated by scanning electron microscopy–energy dispersive X-ray (SEM-EDX), whereby the SEM revealed the appearance of micropores in the Ti-HA composites during the sintering process, and the EDX showed that the final product had high amounts of Ti and Ca and low P. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses were used to achieve the chemical characterization of composites, whereby a weak diffraction peak was observed in the XRD spectrum of Ti-HA composites, and the FTIR analysis confirmed that the composites had carbonate (CO3)2−, phosphate (PO4)3−, and hydroxyl (OH)− groups. Oxygen was sufficient due to the sintering process being conducted in an air environment. The antibacterial activities were characterized using the disc diffusion method with Escherichia coli and Staphylococcus aureus bacteria, whereby the prepared Ti-HA composites had a greater antibacterial effect on E. coli than on S. aureus. Finally, pH changes were observed during the 24 h incubation. The result showed that the Ti-HA composite did not contain chemical compounds that could cause harmful effects for humans and had good antibacterial activity against E. coli.