Desenvolvimento e avaliação de scaffolds compósitos e híbridos de vidros bioativos e poli(álcool vinílico) por técnicas avançadas de fabricação

Abstract

Bone tissue engineering is a promising research field with significant potential to replace or repair bone defects, offering more effective and cost-efficient alternatives to traditional grafting methods. The use of bioactive scaffolds in bone regeneration not only improves clinical outcomes but also reduces hospital costs associated with more invasive procedures. This study presents the development and characterization of composite scaffolds based on the bioactive glasses 58S (wt.% 58:33:9 of SiO₂:CaO:P₂O₅) and 13-93 (wt.% 53:20:12:6:5:4 of SiO₂:CaO:K₂O:Na₂O:MgO:P₂O₅) in compositions of 30/70, 50/50, and 70/30 by weight fraction between solids, as well as scaffolds of bioactive glass 58S and the biodegradable polymer polyvinyl alcohol (PVA) at percentages of 95/05, 90/10, and 80/20, produced via the freeze-casting process. Hybrids of 58S glass and PVA with a 50/50 ratio were produced by 3D printing. The obtained materials were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray microtomography, porosity analysis, and uniaxial compression mechanical tests. Bioactivity was analysed through immersion in simulated physiological solution, while cytotoxicity was assessed via flow cytometry and optical microscopy. The mechanical properties varied according to the phase ratio. For the 58S/13-93 scaffolds, a higher 13-93 content resulted in greater mechanical strength and Young's modulus, with values of 11.25 ± 2.48 MPa and 0.81 ± 0.27 GPa, respectively. In ceramic-polymer scaffolds, increasing the polymer fraction resulted in a toughness modulus of 154.0 ± 15.8 × 10⁶ J·m⁻³, attributed to particle agglomeration effects induced by the PVA. The scaffolds produced by freeze-casting and 3D printing showed porosity suitable for tissue engineering applications, with values exceeding 60%. Additionally, all materials exhibited high bioactivity, with hydroxyapatite formation observed after 24 hours of immersion in simulated body fluid. Cytotoxicity tests confirmed cell viability above 80%, indicating the biocompatibility of the materials. This work demonstrates that the proportion of bioactive glasses 58S and 13-93 and the polymer PVA can be adjusted to optimize the mechanical properties, bioactivity, and porous structure of the scaffolds, offering promising solutions for bone regeneration.