Caracterização da superfície de PLA produzido por manufatura aditiva com selante antimicrobiano para uso na confecção de EPI

Abstract

This work was to characterize the surface with a bactericidal sealant and to obtain properties of the polymer surface based on Polylactic acid (PLA) used in the manufacture of facial protectors (face shield) made by additive manufacturing (3D printing), with the sealant and without the sealant with inorganic copper-based sealant. The methodology included the manufacture of PLA through additive manufacturing, with the same material and process used in the manufacture of facial protectors commonly used in the hospital environments, such as those that were coated with a copper-based sealant. Visual exploration techniques, optical microscopy (OM), scanning electron microscope (SEM), chemical analysis by energy dispersion spectroscopy (EDS), surface roughness measurements and digital image analysis, processing (PDI) were used and in vitro tests. Roughness measurements for advanced PLA plates by 3D printing with and without the presence of the sealant, values of average roughness (Ra) of 22.51±8.40 µm in the direction parallel to the guidance lines generated by printing and 8.72±3.49 µm in a direction perpendicular to these lines, which indicates a Strong anisotropy in the surface morphology. For levels between 0.1 - 0.001g of copper Sulfate/ml of prepared sealant, PLA presents tightly adhered sealants after 24 h of curing and the results of PDI that these known surfaces covered with levels varying between 1 - 17% copper sulfate, respectively. The presence of a sealant with the lowest necessary copper Sulfate caused a smooth reduction in the roughness values, for both tested. Morphological, qualitative and quantitative analysis of the surface of the material and the inorganic agent will in the future be associated with quantitative and qualitative measurements of cell cultures to evaluate the bactericidal effects of the surface with the proposed sealant. After a preliminary qualitative evaluation step, in which eight strains of bacteria showed that the sealant had antimicrobial effect, in vitro tests were performed to quantify the effectiveness of antimicrobial effect with only two types of bacteria, a Gram-Negative (Escherichia coli ATCC 11229) and another Gram-Positive (Staphylococcus aureus ATCC 25923). Triplicate tests were performed for the growth of these cultures on PLA plates with sealant, with varnish and without sealant (control). After 30 min of inoculation of cultures comparing the final inoculation, of the plate without sealant (pure) with the plate with sealant, we obtained a reduction of 39.77x (reduction of approximately 102) of growth of colony-forming units (ufc) for Staphylococcus aureus and a reduction of 43.72x (reduction of approximately 102) pfc growth for Escherichiacoli.