Micro e nanopartículas de carbono obtidas por carbonização hidrotérmica: preparação, caracterização e interação com proteína

Abstract

Carbonaceous materials are attractive due to the versatility and abundance of the carbon element, characteristics that enable the development of new structures, by different preparation methods, with a manifold of physicochemical properties. In this way, this type of material could offer possibilities of application in different branches science and technology. Among the preparation techniques, hydrothermal carbonization has been outstanding on the attainment of carbonaceous micro and nanostructures in a sustainable and fast way, through the use of biomass, biomass residues and carbohydrates as precursors, without toxic reagents. This makes carbonaceous materials produced by this methodology potential alternative for biological applications such as development of biodevices and support for biocatalysts. In this thesis, carbon micro and nanoparticles were prepared by hydrothermal carbonization of glucose, physically and chemically characterized and their use as support for ConBr lectin was evaluated using covalent and non-covalent methodologies. ConBr lectin is a plant protein that has the ability to agglutinate erythrocytes. After the preparations, the microparticles were washed with deionized water and dried in an oven, while the nanoparticles were purified by dialysis. The analyses performed indicated that the microparticles were formed by individualized and coalesced spheres with negative zeta potential, average hydrodynamic diameter of approximately 1 μm and were composed of carbon, hydrogen and oxygen. The nanoparticles, obtained using different reaction parameters, appeared as nanometric agglomerates with different hydrodynamic diameters and negative zeta potential. Depending on these parameters, the nanoparticles had photoluminescence in the visible region and aqueous suspensions without precipitation or turbidity for at least two months. Those with a mean hydrodynamic diameter around 30 nm were stable under pH variation between 4,35 and 9,44 and in saline solutions phosphate buffer (PBS) and NaCl 0,9%. Both materials were subjected to interaction with ConBr lectin by amidation reaction with the aid of carbodiimide and by adsorption. The results obtained for both the microparticle and nanoparticle conjugates indicated that it was possible to immobilize the lectin in the particles so that it maintained its biological activity of erythrocyte's agglutination. Hydrochar; hydrothermal carbonization; ConBr lectin; amidation; adsorption; hemagglutination; C-dots; carbon nanoparticles; photoluminescence;