Obtenção, caracterização e estudo in vitro do vidro bioativo VH30 e compósitos vidro bioativo/polihidroxibutirato

Abstract

Polyhydroxybutyrate (PHB) is a polymer synthesized by microorganism under nitrogen deficiency and has as main characteristic the biodegradability. Bioactive glasses belong to special systems as SiO2-MgO-CaO-P2O5. A composite bioactive glass/PHB has as main aim to help bone reparation and regeneration. This composite can offers support to bone growth (PHB) maintaining the function of the damaged organ while the bioactivity is provided by glass helping the formation of new bone. The glass produced in the present work is named VH30 and belongs to the system SiO2-MgO CaO-P2O5. These composites were produced in two compositions: 30Bio/70PHB with 30% of reinforcement and 40Bio/60PHB with 40% of reinforcement. Bioactive glass had the size and superficial area of the particles characterized by Coulter Counter and B.E.T, respectively; and its phases characterized by X-Ray Diffraction (XRD). Bioactive glass was submitted to in vitro test in Simulated Body Fluid with and without albumin (SBFA and SBF, respectively) and had its morphology observed via Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS) coupled and by Atomic Force Microscopy (AFM). The PHB was characterized by XRD and Differential Scanning Calorimetry (DSC). Composites produced had the microhardness Vickers measured and were characterized by XRD. These composites were also undertook to in vitro studies with SBF and observed by SEM-EDS. The SBF solutions that soaked the composites were analyzed by Inductively Coupled Plasma (ICP) to evaluate the ionic changes. In vitro results of VH30 when it was immersed in SBFA suggest a bioactivity presented a Ca-P layer formation; however when it was immersed in SBF the Ca-P layer was also formed and detached. These results indicating an albumin influence in the layer adhesion. Microhardness results of composites indicated values of 24,291 ± 8,76 HV and 25,273 ± 10,82 HV to the composites Bio40/60PHB and Bio30/70PHB, respectively. In vitro results of composites, when immersed in SBF, suggests that both present bioactivity. Nevertheless, the formation of Ca-P layer was faster to composite 30Bio/70PHB than Bio40/60PHB. The formation of Ca-P layer on composites occurs by deposition of Ca and P ions from solution, according to ICP results.