Síntese e caracterização de scaffolds do compósito vidro bioativo/policaprolactona obtidos por processo freeze-casting

Abstract

The mechanical properties presented by human bone are largely associated with the combination of carbonated hydroxyapatite (rigid component) and collagen fibers (elastic component). In this way, a material designed to perform these functions should also display the same combination of properties. Aiming to reach this behavior, in this work we used elements such as bioactive glass (BG) which has Young's modulus and compressive strength similar to that exhibited by hydroxyapatite, and polymers showing properties analogous to collagen fibers. However, fine control over the pore structure of these materials is not an easy task. In this context, the freeze-casting process emerges as a promising alternative for the manufacture of materials with hierarchical pore structures, because it is a simple, cheap and environmentally friendly method. In this work composite scaffolds of BG / PCL (polycaprolactone) were prepared by the freeze-casting process. Different routes for the manufacture of these composites were tested. The materials prepared were examined by Fourier transform infrared spectroscopy, He picnometry, N2 adsorption, laser granulometry, scanning electron microscopy, X-ray microtomography, Archimedes test, and compression tests. The toxicity of these samples was evaluated by MTT [3- (4,5-dimethylthiazol-2yl) -2,5-diphenyltetrazolium)] and LIVE / DEAD® assays. Moreover, their biocompatibility was evaluated after soaking in Kokubo’s simulated body fluid (SBF) at 37 °C for up to 14 days. It was observed that the incorporation of PCL into the BG scaffolds increased by up to 350% the mechanical stability of these materials in terms of compressive strength and fracture toughness. Biological tests have demonstrated that PCL-containing scaffolds did not significantly interfere in the formation of immortalized human osteosarcoma (SAOS) cells. Besides, the growth of the hydroxyapatite layer on the surface of these materials after immersion in SBF was observed in the first soaking day. The results presented in this study indicate that the materials produced are promising candidates for application in bone tissue engineering.