Synthesis of Hydroxyapatite-Bioglass Nanocomposite Using Modified Sol-Gel Method

Abstract

The aim of this study is comparing preparation methods of hydroxyapatite-bioglass composite nanopowders which can be prepared in different routes based on sol-gel method for orthopaedic/dental applications. Nanostructure materials present a unique and incomparable character for orthopedic and dental implant. Hydroxyapatite-bioglass composite nanopowders with the same contents of bioglass (20%) as reinforcement have been prepared by using a sol-gel method in four routes: mixing sols before aging time, mixing bioglass sol with hydroxyapatite gel after gelation, mixing calcinated bioglass nanopowder with hydroxyapatite sol, and mixing two calcinated powders by mechanical alloying. Bioactive glass of the type CaO-P₂O₅-SiO₂was obtained by the source of tetraethylorthosilicate, triethylphosphate and calcium nitrate tetrahydrate. On the other hand, phosphoric pentoxide and also calcium nitrate tetrahydrate were applied as the source of hydroxyapatite. Calcination temperature was 600°C for both compositions. XRD, SEM, and EDS techniques were used to investigate the microstructure and morphology of the nanopowders. Results indicated that because of different mixing time of hydroxyapatite with bioglass in either sol form, gel form or calcinated powder, the morphology, crystallinity, crystallite size and composition of products were varied. bioglass remained amorphous in all routes of synthesis. Because of presence of amorphous bioglass, In situ synthesis of hydroxyapatite-bioglass composite nanopowders resulted in decreasing the crystallinity and the crystallite size of hydroxyapatite. Furthermore, by mixing two nanopowders after calcination, hydroxyapatite crystallinity was maximum and also by using this route proportion of two parts can be easily controlled.