Hydroxyapatite attracts great attention as hard tissues implant material for bones and teeth. Its application in reconstructive medicine depends on its biocompatibility, which is in a function of composition and surface properties. The insertion of a protein element in the composition of implants can improve the cell adhesion and the osseointegration. Having this in mind, the proposal of this work was to develop L-alanine-grafted hydroxyapatite nanoparticles and to study their biocompatibility. Two L-alanine sources and three grafting methods were used for hydroxyapatite surface functionalization. The efficiency of grafting was determined based on X-ray powder diffraction, Fourier-transform infrared spectroscopy, thermal analyses, and field-emission scanning electron microscopy. The results indicated the formation of hydroxyapatite with 8–25 wt% of organic content, depending on the grafting method. Protein adsorption, cell adhesion, and viability studies were carried out to evaluate biological properties of grafted materials. The viability of MG-63 human osteoblastic cells following 24 h incubation with the alanine-grafted hydroxyapatite samples is well preserved, being in all cases above the viability of cells incubated with hydroxyapatite. The alanine-grafted hydroxyapatite prepared in situ and by simple mixture showed higher protein adsorption and cell adhesion, respectively, indicating their potential toward use in regenerative medicine.

Homologues and xenogenous bones are currently the most used grafts in dentistry because of their performance. However, some inherent disadvantages of these materials have not yet been overcome, such as the lack of biological properties to improve the new bone formation in situ and the long remodeling time. The main aim of this work was to improve the performance of the commercial bone-based grafts and study its properties in vitro. For this purpose, rat bone was combined with bioglass, a synthetic biomaterial that displays high degradation kinetics and bioactivity properties, endowed with biological properties. The sol-gel method was used for 45S5 bioglass (45S5) synthesis, using TEOS and water soluble salts as starting materials. 45S5 was then associated with the rat bone, generating the new graft. FTIR results indicated the hydroxyapatite formation after the bioactivity tests. SEM and bioactivity results were used to assess the evolution of the graft. The bioactivity tests showed that after 30 days the mass gain of about 30 wt.% was due to the deposition of hydroxyapatite crystals at the surface of the grafts, suggesting the potential properties of this new graft for application in implantology.