Desenvolvimento de membranas compósitas biocompatíveis, bioativas e biodegradáveis à base de celulose bacteriana/hidroxiapatita de estrôncio para regeneração óssea guiada

Abstract

Membranes are fundamental implantable devices for guided bone regeneration (ROG) procedures that prevent invasion of non-functional fibrous tissues to the bone defect. Some commercial membranes are produced from non-degradable materials that require a second surgical step to remove them after the regeneration process. However, it is still a challenge to develop biomimetic products to the bone, biocompatible, bioactive and with controlled biodegradability. In this context, the present work focused on the production of biomaterials for application in bone formation mechanisms, considering the composition of bone tissue, which is a mixture of type I collagen and calcium phosphates (hydroxyapatite). This research produced biocompatible, bioactive and biodegradable composite membranes based on oxidized bacterial cellulose (CBox) and hydroxyapatite (HA) incorporated with strontium ions (Sr) so that these components act synergistically in guided bone repair. The CB membranes were subjected to oxidation (cellulose derivatization reaction) in order to increase their degradation in a physiological environment. Three oxidation reaction times with sodium periodate were evaluated. The time variation evaluated the influence of the degree of oxidation on the in vitro degradability of the samples, quantifying the degradation products of the supernatant by CLAE. Then, hybrid membranes were synthesized as strontium release systems in matrices of 40% oxidized CB combined with HA and / or SrAp through immersion cycles. Both oxidized samples and hybrid oxidized samples were characterized by the degree of swelling, FTIR, TGA, MEV-EDS, DRX, XPS and NMR. In addition, they were also evaluated for their bioactivity in the simulated body fluid (SBF), as well as the strontium release profile and biocompatibility and biodegradation tests, through histological evaluation of subcutaneous tissues after 1, 3 and 9 weeks of implantation. membranes in mice. The results showed that oxidation has an influence on the degradability of the membranes, as well as on properties such as swelling and crystallinity. In the production of the hybrids, it was verified that oxidation makes the material negatively charged, favoring the interaction with Sr, and affecting the process of nucleation of HA on the modified surface. It was observed that the release of the active component Sr, for bone repair, can be modulated according to the degree of oxidation and future application. In the tests of bioactivity, biocompatibility and biodegradation, all hybrid materials tested proved to be bioactive and biocompatible, with respect to degradation, only materials with oxidized matrices were able to degrade when implanted and at the analyzed times. Therefore, it is concluded that the route suggested in the study is capable of successfully carrying out the oxidation and production of oxidized hybrids, in addition to producing biodegradable, bioactive and biocompatible membranes for future applications in bone repair.