Membranas baseadas em materiais do tipo Ureasil-Poliéter e argila Laponita contendo glicose para futura aplicação na regeneração óssea

Abstract

The healing of severe bone lesions with high complexity may occur incompletely. However, studies have shown that exogenous glucose increases the viability and multiplication of MSCs, even in hypoxic situations. It is a clinical challenge to develop a framework that can release glucose in a controlled and prolonged manner. Thus, the objective of this work was to develop a hybrid membrane based on ureasil-polyether material, Laponite clay and glucose, aiming the sustained release of glucose. Initially, the production of Laponite colloidal solution (SCL) and its physicochemical characterization were performed. Subsequently, the synthesis of the ureasyl-polyether hybrid precursor using PEO500 polymer and IsoTrEOS. During the sol-gel process, glucose and SCL were incorporated into the precursor. Viscosity tests were performed at different concentrations of Laponite gel 0.5, 1.0, 1.5, 2.0 and 2.5%. The results in mPa were 4.8, 7, 1, 70, 8, 400, 8 and 1121.2, respectively. The ratio chosen for dispersion in the uresyl-polyether material was 1.5%, as it provided a stable gel with characteristics close to a non-Newtonian fluid and greater stability. Visual characteristics revealed homogeneous surface, transparency and luminescence. Different characterization techniques were used, where the infrared spectroscopy data showed the characteristic bands of the individual components and in the formulation; for PEO500, the broad, medium intensity band between 3695 and 3026 cm -1 referring to the O-H stretching, present in the silanols groups located in the terminal portions, stands out. For the Laponite sample, the medium intensity band between 3096 cm -1 and 3072 cm -1 refers to the O-H stretching of hydroxyls present in the molecule, noting that this band presents a small ''shoulder'' at 3621 cm-1, suggestive of intramolecular hydrogen bonding of hydroxyls. For Glucose, the medium intensity band located at 916 cm -1 that was assigned to the asymmetric stretching of glucopyranosyl ring, and the band at 850 is confirmatory of the α-anomeric conformation of glucose. FTIR also showed no significant change in the spectra of the mixtures, and it is possible to infer that there are no chemical interactions. The XRD diffractograms demonstrate that the PEO material is amorphous, identified by the amorphous halo. Glucose was found to have an orthorhombic crystalline system and space group P212121 5.40(2) GPa, above which it undergoes an isostructural phase transition. It can be observed that Laponite exhibits broad crystalline patterns, possibly due to the size of the laponic discs and its low crystallinity, only reflection at 2θ:28° was observed, the first broad peak present around 2θ = 5.0° is attributed to its crystalline plane (001) or basal spacing. The final formulation shows that the crystalline domains disappear, making the material amorphous. These results were corroborated with the DTA data, which enabled the observation of the amorphous character of u-PEO500, not presenting defined and/or visible thermal events, while Laponite, possessed an endothermic event of small intensity, visible in the range of 99.66 ºC probably related to the loss of water weakly linked to its structure, and its thermal resistance can be evidenced. For glucose an intense endothermic peak can be evidenced at 161.81 °C referring to the melting temperature of the crystalline equilibrium of the compound. The TG results demonstrate that glucose when incorporated into the ureasyl-polyether hybrid material and Laponite presented higher thermal resistance since the system started its degradation at 300 °C. Finally, the release results show that, 20% glucose was released in 700 min, indicating that these systems are capable of prolonged glucose release. It is concluded that the development of a glucose delivery system, based on u-PEO500 and Laponite, capable of supporting the treatment of severe bone injuries was possible.