Síntese de membranas híbridas para aplicação como biomaterial

Abstract

Cellulose acetate membranes have a wide range of applications but face certain limitations, which have led to intensified research in the development of hybrid membranes. This work aims to synthesize cellulose acetate membranes with the addition of elements such as silicon, titanium, and nitrogen into their molecular structures. For this purpose, the concentrations of TEOS (tetraethyl orthosilicate) and APTES (3-aminopropyltriethoxysilane) were varied, while a fixed concentration of TiPOT (titanium isopropoxide) was maintained. The synthesis process involved sol-gel and phase inversion methodologies, with the addition of nitric acid. The resulting membranes were characterized using various techniques. Fouriertransform infrared spectroscopy (FTIR) and attenuated total reflectance (ATR) were employed to identify the functional groups present. Thermal analyses, including thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), were used to assess the thermal stability and phase transitions of the membranes. The morphology of the membranes was analyzed by scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) to determine the distribution of the added elements. Additionally, cell viability and biomimetic tests were conducted to evaluate the bioactivity and cytotoxicity of the membranes. All synthesized membranes exhibited a cytotoxic activity rate above 70% of cell viability, indicating low toxicity and high biocompatibility. The FTIR spectra and TGA curves were similar for all membranes, indicating thermal stability and the presence of expected functional groups. The morphology of the membranes showed particular characteristics for each composition variation, directly influencing their mechanical properties and permeability. After 45 days of biomimetic testing, all FTIR spectra revealed characteristic peaks of calcium phosphates and carbonapatite, indicating the formation of a bioactive layer on the membrane surfaces. The membranes synthesized in this dissertation exhibited the expected physical and chemical characteristics, as well as satisfactory biological results, confirming their bioactivity and lack of toxicity.