POROUS TITANIUM DIOXIDE-HYDROXYAPATITE COMPOSITES PREPARED BY A SOL-GEL/SUPERCRITICAL CO2-DRYING COMBINED PROCESS.”,

GLORIA M. HERNANDEZ; PARRA, RODRIGO; FANOVICH, M. ALEJANDRA

Mar del Plata

Congreso; XII Latin American Congress of Artificial Organs and Biomaterials; 2023

INTEMA

Introduction and objective: Hydroxyapatite-based materials have a chemical composition like that of the mineral component of bones. For this reason, these materials are the protagonists in the development of supports for osteogenesis (bone formation). The purpose of the present study is to obtain new porous supports from titanium dioxide (TiO2) and hydroxyapatite (HA) by a sol-gel process and supercritical-CO2 drying. The main objective is to develop porous scaffolds of TiO2 with different mass proportions of HA nanoparticles and to assess the effect of the studied compositions on the adhesion properties of MG-63 cells.Methodology: HA nanoparticles were synthesized by a hydrothermal method and subsequently used in a sol-gel process to obtain TiO2-HA composite gels from titanium butoxide (Ti(OBu)4, acetic acid, isopropanol, distilled water, and polyvinylpyrrolidone (PVP) as porogen agent. In the next step, the obtained TiO2-HA gels of cylindrical morphology were dried using supercritical CO2 between 60 and 90°C at pressure from 240 to 400 bar. Finally, the dried gels were calcined at 800°C in air for 1 h. Characterization was carried out by X-ray diffraction (XRD), Raman spectroscopy, Density/porosity measurement, Thermal analysis (TGA-TDA), Scanning electron microscopy (SEM), and in vitro MG-63 cell adhesion tests on dried and calcined samples. Results and discussion: TiO2-HA porous composites were obtained by the integration of sol-gel and supercritical drying processes. XRD analysis showed that between 18.6 and 29.4 % w/w of HA can be included in a TiO2 matrix in order to avoid the phase transition from anatase to rutile. The anatase stability is increased by the increase of HA content by means of the chemical interaction between phosphate groups in HA with hydroxyl groups in TiO2 gels, which lead to Ti-O-P bonds as confirmed by the peak at 796 cm-1 in the Raman spectra. Optimum conditions for drying the aerogels were at 60° C and 250 bar, TiO2-HA composites with open porosity of 70-80% were obtained with a uniform distribution of pores of 5-20 μm in size. Furthermore, the materials obtained favor the adhesion of osteoblast-like cells and their proliferation, with the sample with the highest HA content showing the best response.Conclusions: It was possible to obtain consolidated materials with a satisfactory response to in vitro adhesion tests with osteoblast-like cells. Furthermore, the developed materials presented stable crystalline phases at 800°C of anatase and hydroxyapatite, which provide specific properties to the developed biomaterial. It was also possible to detect the interaction of these phases, with no evidence of reactivity between them, which determines a good integration of the phases in the final structure of the composite material.