Nanopartículas de prata contendo xilanas: síntese, caracterização e avaliação do seu efeito imunomodulador e antibacteriano

Abstract

In recent decades, the increase in bacterial resistance to new treatments has led to a series of attempts against a search for these microorganisms. Within this context, significant progress has been achieved in the development of drugs based on nanotechnology to combat/attenuate bacterial resistance. And among the nanoparticles, the silver ones (NANO) are pointed out as an option in this sense, including already being applied in several uses, such as in the textile industry. However, their use in different clinics has a smaller dimension, and this has medical combined with the development of NANO, which encourages, in addition to silver, organic molecules in its unit, as this can enhance or give new applicability to NANO. This includes using environmentally friendly methods (green synthesis) for a NANO synthesis. Polysaccharides are one of the organic molecules that have been used for this purpose. Xylan is a hemicellulose found in different vegetables and therefore very abundant in nature. However, there are less than a dozen papers on NANO containing xylans, and none have evaluated its antimicrobial effect. Therefore, in this Thesis six xylan-rich fractions (FE's) from corn cob (Zea mays) were characterized (sugar, protein, and compound phenolics), and used for a green synthesis of NANO. The NANO were characterized by UV-visible spectroscopy, scanning electron microscopy, dynamic light scattering, energy scattering spectroscopy and infrared spectroscopy. All NANO (NANO EBX; NANO E0.3; NANO E0.4; NANO E0.8; NANO E1.4 and NANO E2.2) were essentially composed of silver and medium xylan, presented round shape, size ranging from 105.0 to 79.7 nm and stability of 24 months. These nano were not cytotoxic against fibroblasts (3T3) and macrophages (RAW). In addition, they promote the reduction of production of nitric oxide (NO) macrophages activated in bacterial lipopolyssaide. The different NANOs, synthesized here, also showed antibacterial activity. All were effective against experimental Gram-negative bacteria (Escherichia coli – E. coli; Klebsiella pneumoniae carbapenemase-producing – KPPC) with emphasis on NANO EBX and NANO E1.4 which contain a minimum inhibitory concentration (MIC) of 62.5 µg/mL against E. coli. For KPPC, NANO EBX; NANO E0.4; NANO E1.4 and NANO E2.2 stand out, which presented MIC of 250 µg/mL. The data presented here show the biotechnological potential of different s xylans in the form of nanoparticles and future tests, including in vivo, should be performed to confirm the antibacterial potential of the different NANO synthesized with EBX and FE's.