Síntese sol-gel de scaffolds porosos de vidro bioativo com adição de agente porogênico

Abstract

The use of biomaterials capable of generating a biological response has been one of the biggest progresses in regenerative medicine, due to their ability to support growth stimulation and damaged tissue regeneration. In this context, ceramics and particularly bioactive glass, were the subjects of multiple studies because of their known capacity to promote strong bonds between the tissues and the implant. Since the discovery of bioactive glass in the 1970s, various in vitro studies confirmed a high compatibility, osteoconductive and osteoinductive properties of this material. The technique of porogen agent addition for the synthesis of scaffolds is an interesting procedure because several types of porogen agents can be used. The aim of this present work was to obtain scaffolds using four porogen agents and to evaluate the effects that a change in treatment temperature can have on their crystallinity. This study prepared and characterized sol-gel bioactive glass 100S (100% SiO2) scaffolds more porogen agents: two types of paraffin, (I): paraffin 1, with average size 608.5m until 993.3m, (II): paraffin 2,with size 1.929mm until 2.307mm, (III): wax, with size 9.272m until 204m and (IV): CMC (carboxy methyl cellulose), with size 27.74m until 382m. As the best results were obtained with paraffin 1, scaffolds 58S (60%SiO2-36%CaO-4%P2O5) and 100S (100% SiO2) using paraffin 1 as porogen agent were prepared. The scaffolds were submitted to different treatment temperatures to evaluate the effect on their crystallinity. The scanning electron micrographs (SEM) showed the porous network shape. Micro-computed tomography (CT) presented the 3D volume rendering of scaffolds, showing structural characteristics of the scaffold surface and porous network. Scaffolds presented satisfactory pore size and pore size distribution, important characteristics for scaffolds because they allow cell migration, nutrient transport, vascularization and tissue ingrowth. The scaffolds exhibited pore size diameter higher than 150m, adequate pore distribution and open porosity higher than 50%, which facilitates cell growth, migration and nutrient flow. X-ray powder diffraction (XRD) showed the amorphous nature of the scaffolds. At 900°C, scaffolds BG 58S and 100S showed a small increase in cristallinity. N2-adsorption (BET) indicated a mesoporous with distribution ranging from 9.4nm in BG 100S with paraffin 1 treated at 9000C to 22.9nm in BG 100S with paraffin 1 treated at 8000C. The specific surface area (SA) varied from 73.2m2/g for scaffold 58S with paraffin 1 treated at 8000C to 331.2m2/g for scaffold 100S with paraffin 1 treated at 8000C. The materials obtained showed no toxic effects by MTT cytotoxicity assays. Results showed that the development of scaffolds is possible using porogen agents, with 3D interconnected porous structure and might therefore be a potential biomaterial for bone tissue regeneration.