Desenvolvimento de scaffolds nanofibrilares de vidros bioativos pelo solution blow spinning (SBS).

Abstract

The bone tissue engineering is a promising multidisciplinary field in which nanotechnology plays a key role in the development of new approaches. Aiming at tissue replacement, repair and reconstruction, the scaffolds, a three-dimensional structures with specific characteristics aiming at improving cell viability, proliferation and osteogenic differentiation are considered as objects of study under various perspectives in tissue engineering. Bioactive glasses in this case attract researchers' attention as scaffolds, since they are osteoconductive and osteoinductive. In this sense, this work is divided in three parts, aiming a study of the parameters of the production of powders via sol-gel, fibers and nano-fibrillary scaffolds using the Solution Blowing Spinning (SBS) technique from the sol-gels. For the powders it was used the composition 45S5 (46,1%SiO2-26,9%Na2O-24,4%CaO-2,6%P2O5 in mol) and hydrochloric acid, the citric acid and ethylenediamine tetraacetic acid (EDTA) it was used as the catalytic acid. The tetraethyl orthosilicate (TEOS) was used as the network former. The powders were heat treated at 600, 700 and 800 °C and evaluated by thermal analysis and X-ray diffraction. Fibers were produced by SBS according to 45S5, 58S (60%SiO2-36%CaO-4%P2O5 in mol) and 63S (65%SiO2-31%CaO-4%P2O5 in mol) compositions. As the polymer solution, a concentration of 8% of PVA (polyvinyl alcohol) in water and 40, 50 and 60 psi spinning pressures was used. The fibers were characterized by scanning electron microscopy (SEM), Fourrier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Subsenquently, the fibers were converted into Scaffods in three different formats: in fibrous blankets, in cylindrica l shape and in the form of cotton. The 45S5 fibers resulted in crystalline samples, evidenced by XRD, and very brittle. However, the 58S and 63S fibers presented amorphous and excellent appearance for the conversion in scaffolds. The bioactivity study was accessed by FTIR and XRD in a Body Fluid Simulator at immersion times of 2, 12, 24, 36, and 168 h. The evaluation of the bioactivity showed the conversion to hydroapatite (HA) in 12h for the 58S composition and in just 2h for the 63S composition. The fibrous blankets resulted in structures with aligned fibers and the pressing for the making of the cylindrical scaffolds showed not to damage the fibrillar structure, satisfying the purpose of the work.