Improving bone tissue integration of hard tissue implamants using bioactive materials

Abstract

Hard tissue implants which made of different materials are used widely in medical applications in bone and tooth deficiencies. Metallic and ceramic materials are preferred as hard tissue implants because of their strength and toughness. Due to low density, high corrosion resistance and biocompatibility properties of titanium and titanium alloys, their usage as an implant has gradually increased. Implant materials should not cause an immunogenic reaction in the body and also in recent years thanks to new technologies in biomaterial field there are some applications to improve interaction in a positive way between implant and implantation tissue. Some morphological changing applications like grooving and acid etching, some physicochemical activation treatments like hydroxyapatite (HA) coating and titanium oxide (TiO2) coating, some biochemical activation treatments like coating with biopolymers and immobilization of bone morphogenic proteins and inducer chemicals are studied on titanium surface to improve bone formation, bone bonding and antibacterial property. At this study, titanium (grade 2) surfaces are chosen to increase its bone tissue integration by designing bioactive surface by using chitosan microspheres as a natural polymer and water-soluble dexamethasone (DEX) as an inducer for SAOS-2 cell differentiation. Chitosan microspheres were produced by using single emulsion-crosslinking method. Different amount of glutaraldehyde with different percentages was used as a crosslinker agent to obtain optimum DEX loading into chitosan microspheres. Crosslinking time parameter was also changed for optimization. Dexamethasone loading was tried in two ways first one is adding drug into dissolved chitosan solution then produce chitosan microspheres, second one is adding produced chitosan microspheres into the drug solution. DEX was loaded into chitosan microspheres via diffusion. After optimization process, chitosan microspheres were produced by using glutaraldehyde as a crosslinker. Chitosan microspheres were placed into DEX solution for loading process. Drug release studies were performed by using DEX-loaded chitosan microspheres, and released amount of DEX was determined. Drug loading efficiency was found as 50.16% and release of DEX was observed for 12 hours and the released amount of the loaded DEX was calculated as ~32.6%. Before chitosan microsphere coating onto titanium surfaces, they were treated chemically (polished, oxidized and silanized to produce amino groups on titanium surfaces). Then the samples were activated by glutaraldehyde and coated with chitosan microspheres.