Scaffolds composed by bioactive glasses and injectable matrices for bone regeneration

Abstract

Design of three-dimensional hybrid and injectable templates (scaffolds) has emerged as a promisor approach to produce biomaterials for targeted applications. In this sense, the properties of the materials should be tuned to improve its therapeutic effect in the host tissue and to become a material able to easily adapt and shape to any type of bone defect. On that account, the use of bioactive glasses, or bioglass (BG) in the composition of these scaffolds may improve their osteogenic activity due to the capability of these vitreous systems to interact with the bone driven by chemical and biochemical processes stimulated by the dissolution products of the BG. So, the objective of this project is to synthesize and characterize scaffolds constituted either by BG SiO2-CaO-P2O5 / SiO2-SrO-P2O5, containing Eu3+ and modified by the addition of Ta5+ or Nb5+, or by the association of these vitreous systems with matrices based on gelling properties of chitosan (Ch) and k-carrageenan (k-Carr). Effects on the mechanical, surface, bioactive and biological properties of these three-dimensional systems promoted by both the modifications in the composition of the vitreous systems and the combinations of these BG with injectable hydrogels will be investigated. Furthermore, it is proposed an in vitro study aimed at monitoring the biodegradation products of these systems in the tissues and organs by the presence of the biomarking property conferred by the incorporation of europium Eu3+. For the synthesis of these vitreous systems, sol-gel methodologies will be adopted, and later, to obtain the hybrid scaffolds, the BG will be added together with crosslinking agents to solutions containing the polysaccharides chosen in this project for the occurrence of in situ gelation. Posteriorly, both the BG and the scaffolds will be characterized with respect to their composition using infrared vibration spectroscopy (FTIR), X-ray diffraction (XRD) and Raman scattering. The morphology and porosity will be evaluated by the scanning electron microscopy and X-ray computed microtomography (micro-CT). Bioactivity and biodegradation will be studied by immersing the samples obtained in the body fluid that simulates the pH and the ionic concentration of the blood plasma (SBF, simulated body fluid). Evaluation of the luminescent properties of systems containing Eu3+ in vitro will occur by the photoluminescence spectroscopy. The strength of the material will be evaluated by mechanical tests, in which the resistance will be given by Young's modulus analysis. After, it will be characterized with respect to surface energy and wettability using contact angle measurements. The best results regarding composition, morphology, strength and surface properties will be selected for osteoblast culture tests in vitro. It is expected at the end of this project that the produced scaffolds can act, as well as bone regenerating systems, as carriers of compounds with pharmacological activity, such as curcumin, so that, through its biodegradation, both the controlled release in situ of this compound as a stimulus for the growth of the new tissue that should fill the site of the bone defect.