Nanotubos de carbono magnéticos funcionalizados: Avaliação da proteína corona em soro humano, estudos de citocompatibilidade e permeação em modelo biomimético

Abstract

Carbon nanotubes (CNTs) have stood out in nanomedical applications due to their favorable characteristics and the possibility of functionalization. When these nanomaterials come into contact with the blood, they assume a new identity due to the formation of protein corona. Furthermore, assays to ensure the cytocompatibility of the systems must be carried out. In this thesis, three materials were synthesized: magnetic CNTs (M-CNTs), M-CNTs covered with bovine serum albumin (M-CNTs-BSA), and M-CNTs functionalized with hydrophilic monomers hydroxyethyl-acrylate and glycerol dimethacrylate (M-CNTs-HL). These materials were extensively characterized, and the albumin adsorption profile was evaluated, obtaining values ranging from 13.2 to 19.9 mg g -1 , with Freundlich and Sips isotherms explaining the adsorptive behavior. Fluorescence assays showed that the nanotubes had a quenching effect of the albumin in solution, indicating that these proteins can change their conformational state after interacting with the surface of the materials. Cytotoxicity, cellular metabolism, oxidative stress, and apoptosis using Caco-2 as a cellular model were evaluated using different concentrations of carbon nanotubes. Cytocompatibility for concentrations of up to 100 µg mL-1 was obtained for all materials. Permeation tests in a biomimetic model were conducted under the action of magnets for up to 8 h, and the magnetic nanoparticles presented in the nanotubes were used to estimate the concentration of materials that crossed the Caco-2 monolayers. Values ranging from 0.50 to 7.19 and from 0.27 to 9.30 ng were obtained for cells exposed and not exposed to magnets, respectively. Gel electrophoresis tests were carried out to compare the profile of the protein corona eluted from the materials after exposure to diluted human serum samples. Changes in the concentration of total proteins were verified, in addition to discrete changes in the protein profile observed in the electrophoresis gel. Another evidence that materials interact differently with proteins was optimizing different elution conditions for each nanotube. More conclusive studies using a mass spectrometer are still being performed. Together the obtained results indicate that the synthesized materials are promising for biomedical and biotechnological applications. There is still no comparison in the literature of these two types of functionalization for nanotubes.