Compósitos quitosana/carbonato de cálcio para utilização em cânulas de fístula ruminal.

Abstract

The use of cannulas in the digestive system of ruminants is often required for experimental studies of digestibility. The cannulas used today are made from synthetic polymers presenting minimal interaction with the biological environment, low biodegradability and toxicity problems due to additives. For that reason, the replacement of synthetic polymers used in the manufacture of these tubes, by a natural polymer, biodegradable, nontoxic and biocompatible such as chitosan may result in a product providing better interaction with the animal tissue. In Biomedicine, Chitosan is applied as biomaterial that favors the reconstitution of the skin and its physiological properties can be improved by the addition of calcium carbonate extracted form eggshells, leading to preparations of chitosan / calcium carbonate composites. Therefore, this paper proposes to develop and characterize chitosan membranes and chitosan / calcium carbonate composites to replace synthetic polymers currently used in these cannulas. Composite membranes of chitosan and chitosan / calcium carbonate with contents of 1%, 5% and 10% were prepared and characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), surface adhesion by contact angle measurements (TS), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TG), scanning electron microscopy (SEM), optical microscopy (OM), Enzymatic biodegradation test, stability against acidic and alcaline aqueous solutions, Ruminal medium stability, assessment of cell viability of macrophages (MTT), Determination of the Production of Nitric Oxide (NO) and mechanical testing (tensile test). Regarding the FTIR and TS results, the presence of calcium carbonate in the proportions of 1%, 5% and 10% did not change significantly the characteristics of the chitosan membrane. The XRD technique showed that the greater the amount of calcium carbonate, the higher was the crystallinity of the composite. Regarding the topography, by light microscopy and scanning electron microscopy it was observed that calcium carbonate particles formed clusters of various sizes and shapes, but were well distributed in the membranes. Through the DSC can be concluded that the increased load on the membrane of chitosan gave them a greater thermal stability, which was also slightly observed by the thermogravimetric analysis (TG). The biodegradation tests showed that the membranes are biodegradable. The MTT assays and NO confirmed that the composites are biocompatible with low or without any cytotoxicity. Based on data obtained in this work can be concluded that the chitosan membrane with 1%, 5% and 10% calcium carbonate derived from the the chicken eggshell can be used as biomaterial and to improve the biocompatibility of synthetic polymers used in the cannulas, and this then contributes to the reduction of environmental pollution.