Nanocompósito a base de nanocelulose bacteriana e nanotubo de titanato funcionalizados através da reação multicomponente de Ugi para aplicação médica

Abstract

With the great interest in nanocomposites that present unique physical and/or chemical properties from the optimized combination of organic and inorganic materials, multicomponent reactions (RMCs) stand out as a promising approach, since their synthesis is simplified, with few purifications steps, high efficiency, atoms saving and reduces waste generation. In this context, the ugi multicomponent reaction combines a primary or secondary amine, a carboxylic acid, an isocyanate and an aldehyde, excelling as a powerful tool for the functionalization of materials, creating compounds with high-value-added and combined properties. For this study, it was used bacterial nanocellulose (BNC) and titanate nanotubes (NtsTi), materials known for their unique properties. BNC is tensile strength, biocompatible, has low cytotoxicity and high surface area, in addition to being widely applied in the medical field, while NtsTi has nanometric morphology, mechanical resistance, high surface area, photocatalytic and antimicrobial properties, which makes them are widely used in bone implants. Both materials have hydroxyl groups on their surfaces, allowing modifications. To synthesize a nanocomposite combining the properties of NtsTi and BNC, NtsTi was initially prepared using the alkaline hydrothermal method followed by silanization with 3-aminopropylthiethoxysilane (APTes). BNC was produced from the bacterium Komagataeibacter Hansenii and subsequently oxidized with 2,2,6,6- tetramethyl-1-piperinoxy (TEMPO). It was used an oxidized BNC in the UGI MCR, with silanized NtsTi, cyclohexyl isocyanate and benzaldehyde for the synthesis of the NtsTi-Si(CH2)3NH2/NCB-COOH nanocomposite. The synthesized materials were characterized by SEM, EDS, TEM, FTIR, XRD, TGA, 13C NMR and evaluated the antimicrobial activity against the bacteria S. aureus and E. coli. NtsTi was formed with tubular structures with a diameter of 10.83 nm. Using spectroscopic techniques, it was possible to confirm the silanization of NtsTi with diameters of 7.85 nm. Bacterial nanocellulose was formed with fibrils with a diameter between 57 and 75 nm, spectroscopic techniques also confirmed the oxidation of NCB. Using FTIR and 13C NMR spectroscopic techniques, the formation of the nanocomposite based on NtsTiSi(CH2)3NH2 and NCB-COOH obtained through the Ugimulticomponente reaction was confirmed. The results in the antimicrobial activity test showed an inhibition halo of 9 and 15 mm in the bacteria S. aureus and E. coli, respectively, for the nanocomposite with 200 mg of NtsTi-Si(CH2)3NH2 and 50 mg of NCB-COOH , indicating that Ugi MCR produced a nanocomposite with antimicrobial properties, taking advantage of the characteristics of BNC and NtsTi.