Influência dos tipos de agitações mecânica e ultrassônica na síntese de vidros bioativos com e sem íons fluoreto através da metodologia sol-gel simplificada

Abstract

Bioactive glasses (BG) are materials of great interest in tissue engineering for their ability to form hydroxyapatite (HA) and bone integration. Different ions can be incorporated into the structure of BG, which enhance the performance of the material when in contact with the physiological environment. Fluorine is one of these ions and its incorporation into BG leading to the formation of fluorapatite, which is a compound chemically more stable and resistant to acid attacks than HA. A possible route to synthesize FBG is through the sol-gel process. This process increases the possibility of control of the synthesis parameters such as the mode of agitation of the suspension. The modification of this parameter could affect significantly the morphological, textural and physicochemical properties of the bioactive glass. Thus, this work aimed to produce BG with incorporated fluorine ions using the sol-gel route to study the influence of mechanical stirring and ultrasonic energy on the physical, structural, morphological and biological properties of two BG compositions. BG’s molar nominal compositions 80% SiO2 - 15% CaO - 5% P2O5 and 80% SiO2 - 5% CaO - 4% P2O5 - 11% CaF2, were produced. The spherical morphology and submicron size, visualized by SEM and AFM techniques, increase the possibility of cell adhesion and proliferation. The FTIR structural analyses showed typical BG bands, which not exhibited differences between the mixing method applied and in fluoride ions incorporation. Instead of XRD data that showed typical BG halo-amorphous patterns and, for BG fluorine- containing, peaks which is related to the CaF2 that could be associated to the salt precipitation or to the presence of CaF+ nano-clusters, which could indicate the presence of fluoride ions in the particles. The analysis of the particle size distribution by DLS and the analysis of the textural characteristics by N2 adsorption showed that the physical properties of the glasses are related to the mixing method and to the BG composition employed in the process. It was also observed the behavior of the glasses after immersion in SBF, being possible to identify the formation of apatite on the surface of the glasses through characterization by SEM, EDS, FTIR and XRD after 28 days. In addition, the in vitro cytocompatibility assays by MTT and Calcein were ensure that they are not cytotoxic materials. The results lead to the conclusion that the methodology of agitation of the synthesis affects the physical properties of the material and the incorporation of ions to the BG network.