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Introduction: Controlling Enterococcus faecalis is of vital importance in endodontics, as this pathogen is associated with endodontic failure. Experimental evidence has shown that copper has antibacterial activity against other pathogens with similar characteristics. The objective of this study was to determine the antimicrobial activity of copper (II) or cupric (SC-II) sulfate on strains of Enterococcus faecalis and to compare it with the most commonly used antimicrobials. Methodology: We used 33 strains of Enterococcus faecalis isolated from different clinical pictures in different Chilean hospitals. The minimum inhibitory concentration (MIC) of SC-II, chlorhexidine and calcium hydroxide was determined by the broth microdilution technique, following the recommendations given by the Clinical and Laboratory Standards Institute. Results: The MIC for CHX varied in the range of 5-10 µg/ml; SC-II from 1.5 to 12 µg/ml, and HC was >32 mg/ml. The geometric mean of SC-II was 6 µg/ml, lower than that of CHX, which was 7.29 µg/ml. Conclusions: SC-II showed antimicrobial activity at lower concentrations than CHX. HC (which could have been affected by the buffer effect of the broth microdilution technique) showed high values, not comparable to other compounds. We suggest carrying out further studies on the properties of SC-II, such assessing its biocompatibility and reaction with other materials to be used clinically in endodontic therapy. Evaluación antimicrobiana del sulfato de cobre (II) sobre cepas de Enterococcus faecalis. Estudio in vitro.Resumen: Introducción: El control de Enterococcus faecalis es de vital importancia en endodoncia, ya que este patógeno está asociado al fracaso endodóntico. Evidencias experimentales que han demostrado que el cobre presenta actividad antibacteriana en otros patógenos de similares características. El objetivo de este estudio es determinar la actividad antimicrobiana del sulfato de cobre (II) o cúprico (SC-II) sobre cepas de Enterococcus faecalis y compararla con los antimicrobianos más usados en la actualidad. Metodología: Estudio in vitro. Se utilizó la técnica de microdilución en caldo según lineamientos del Clinical and Laboratory Standards Institute, incluyendo 33 cepas de Enterococcus faecalis obtenidas desde hospitales chilenos, para cada una de las cuales se determinó las concentraciones mínimas inhibitorias (CMI) de: SC-II, Clorhexidina (CHX) e Hidróxido de calcio (HC). Resultados: La CMI para CHX tuvo un rango de 5-10 µg/ml, el SC-II de 1,5-12 mM y el HC fue >32 mg/ml. Estas diferencias fueron estadísticamente significativas entre los 3 antimicrobianos utilizados (p<0,001). Conclusiones: El SC-II mostró actividad antimicrobiana a bajas concentraciones, superiores a CHX, pero menores a HC (que pudo ser afectado por el efecto tampón de la técnica de microdilución en caldo). Se sugiere seguir con los estudios de las propiedades del SC-II, como evaluación de biocompatibilidad y reacción con otros materiales para ser utilizados clínicamente en la terapia endodóntica. Pal...

The development of polymeric thin films has attracted attention in the optoelectronics field due to their transparency. The aim of the research presented was to obtain transparent polyaniline thin films by easy in situ oxidative polymerization of aniline with ammonium persulfate in the presence of a binary doping agent-poly(vinyl alcohol) mixture. Poly(acrylic acid), 2-acrylamido-2-methyl-1-propanesulfonic acid or sodium dodecylsulfate were mixed with hydrochloric acid to form the binary doping agents. Polyaniline thin films were produced during aniline polymerization on Corning glass slides immersed in the mixture in order to study their optical, electrical and morphological properties. The optical absorption coefficient and the energy band gap were evaluated by optical transmission of the films in the UV-visible spectral region. The optical absorption coefficient of all polyaniline films was of the order of 10 4 cm −1 with a maximum transmittance up to 80% at 550 nm. In order to investigate the effect of the mixture on the surface morphology and roughness of the films, atomic force microscopy was used. In general, surface roughness was reduced threefold by adding a mixture and optical transmission was increased by 20-30% without significantly affecting the absorption coefficient and the band gap of polyaniline. Islands and needle-like structures on the film surfaces were obtained from various mixtures affecting the conductivity; for example, 0.17 S cm −1 was obtained from needle-like morphology, while 1.9 × 10 −4 S cm −1 was obtained from island morphology. Raman spectroscopy studies confirmed the presence of poly(vinyl alcohol) in the thin films.

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