Atividade antibacteriana de nanopartículas de prata na superfície de painéis do tipo MDF

Abstract

Hospital infections, also known as nosocomial infections or infections associated with health care, are one of the main causes related to the length of hospital stay among hospitalized patients and the increase in the mortality rate among these patients. Most of these infections are caused by bacteria. Contamination of surfaces within medical and hospital environments and the spread of bacterial cells are directly associated with the outbreak of infections. Hygienic techniques contribute to surface decontamination, however, due to bacterial resistance, many surfaces remain contaminated. In search of more suitable techniques for the correct cleaning of these surfaces, the surface modification appeared, which aims to give antibacterial properties to the surfaces of the materials, in order to prevent the proliferation of bacterial cells. One of the main antimicrobial agents used to carry out this modification is silver (Ag) for having good antibacterial properties. On a nanometric scale these properties become even more intense, due to the high surface / volume ratio, which contributes to the use of AgNPs to combat various pathogenic microorganisms. However, nanoparticles (NPs) can easily clump together which reduces their antibacterial activity, so they need stabilizing agents to maintain their stability. Among the stabilizing agents is polyurethane, a polymeric material, capable of providing stability to the AgNP solution and contributing to the maintenance of its efficiency as an antibacterial agent. In this context, the main objective of this work was to produce a coating with antibacterial properties, through the use of silver nanoparticles and polyurethane resin, for later use on the surface of furniture used in medical-hospital environments, aiming to reduce the spread of bacterial cells. within these environments and decrease the rate of nosocomial infections. For the synthesis of silver nanoparticles, the sodium borohydride reduction process was used. The electronic spectra obtained for the nanopathicles solution showed a peak of maximum absorbance at around 393 nm, consistent with the values described in the literature for silver nanoparticles. The application of nanoparticles on the surface of the panels was carried out directly and through their insertion in the polyurethane resin, in concentrations of 10% and 20%. The antibacterial activity of these coatings was evaluated in relation to Escherichia coli and Staphylococcus aureus. The surface properties of the panels were evaluated using scanning electron microscopy (SEM), dispersive energy spectroscopy (EDS) and contact angle. Through the results obtained in this work, it was observed that treatments composed by the direct application of AgNPs on the surfaces of panels with and without polyurethane coating, were not efficient in combating the E. coli and S. aureus cells, due to the aggregation of the nanoparticles that reduced its antibacterial activity. Treatments composed of silver nanoparticles inserted in polyurethane resin, in concentrations of 10% and 20%, were efficient in combating bacterial cells, by causing the elimination of all E. coli cells and considerably reducing the number of cells S. aureus