Navegando por Palavras-chave "Atividade Antimicrobiana"

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    Estudos sinérgicos de peptídeos antimicrobianos na terapia fotodinâmica
    (Universidade Federal de São Paulo (UNIFESP), 2020-10-29) Moreira, Gustavo Magalhaes [UNIFESP]; Oliveira Junior, Vani Xavier De [UNIFESP]; Universidade Federal de São Paulo
    Objective: The work proposes the peptides' synthesis with antimicrobial activities described, such as Aurein 1.2, Temporin L and Mastoparan L, to measure the synergistic effect together with hypericin as a photosensitizer in a non-toxic concentration to healthy cells. Methods: The solid-phase synthesis technique was chosen to obtain the peptides under study. Purification and characterization were performed by liquid chromatography coupled to electrospray ionization mass spectrometry, NanoDrop spectrophotometer, and Circular Dichroism. The hemolytic concentrations of each peptide, the enzymatic degradation at fetal bovine serum assay and the interaction to the generation of singlet oxygen by photosensitizer were verified for the biological assays. The peptides were tested individually performed at serial concentrations: 128 to 1 μmol L-1 , and together with hypericin at: 1, 10 and 100 μmol L-1. The best times for the photosensitizer internalization and light irradiation (595 nm) were defined for each microorganism. Results: The high helical content of the peptides was observed from the circular dichroism spectra analysis in TFE 60% and SDS at 20 mmol L-1. The hypericin internalization and irradiation times found were up to 30 min for the microorganisms tested. Peptide degradation was observed after 1 h. The peptides do not interfere with the singlet oxygen generation from hypericin. Temporin L was hemolytic above 16 μmol L-1, and below this concentration, it inhibited the Serratia marcenscens (ATCC 4112) and Candida tropicallis (IOC 4560) growth after combining the techniques. Mastoparan L showed a synergistic effect for Escherichia coli (SBS 363), Staphylococcus aureus (ATCC 29213), and C. glabrata (IOC 4565). Aurein 1.2, improved its activity for all microorganisms, except for S. marcenscens (ATCC 4112). Conclusions: The synergistic effect was observed for antimicrobial activity in vitro because the MIC values of the peptides were better when combined with photodynamic therapy.
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    Processamento e Caracterização de Scaffolds de β-Fosfato Tricálcico pelo Método de Gelcasting com Incorporação de Nanopartículas para Atividade Antimicrobiana
    (Universidade Federal de São Paulo (UNIFESP), 2020-02-14) Barbosa, Lucas [UNIFESP]; Triches, Eliandra De Sousa [UNIFESP]; Universidade Federal de São Paulo
    Tissue engineering and regenerative medicine are highly relevant to the science of biomaterials, promoting advances in the treatment and recovery of patients with problems caused by diseases, injuries and fractures. Recent studies in tissue engineering have sought to develop multifunctional scaffolds that in addition to having regenerative capacity, have antimicrobial properties through the incorporation of antimicrobial agents, providing a better recovery to the patient and avoiding new surgical procedures for treatment or removal of the implant, since inflammations and infections are often caused by microorganisms. For the production of ceramic scaffolds for bone tissue regeneration, tricalcium β-phosphate (β-TCP) stands out due to its chemical stability and more suitable resorption speed for bone implants. Among the antimicrobial agents that have been studied are metallic nanoparticles, such as silver, and chemical compounds, such as methylene blue. Thus, this work aimed to obtain β-TCP scaffolds by the gelcasting method applied to foams with the incorporation of methylene blue and silver nanoparticles in order to confer antimicrobial properties. For this, the obtained β-TCP scaffolds were immersed in the silver nanoparticles solution and stirring by ultrasonic. Methylene blue was incorporated by dripping the solution into the scaffolds. The synthesized ceramic powder presented the crystalline phase of interest, β-TCP, average particle size after grinding 1.56 μm and density 2.99 g/cm³. Regarding antimicrobial agents, silver nanoparticles had an average hydrodynamic diameter of 39 ± 2 nm, with maximum absorption in the UV-visible spectrum at 429 nm and the methylene blue solution had a concentration of 1.044 mM, with maximum absorption in the UV-visible spectrum at 654 nm. In turn, the β-TCP scaffolds had porosity of 81 ± 2 % and mechanical compressive strength of 1.3 ± 0.5 MPa with spherical and interconnected pores. The test to evaluate the antimicrobial activity, in relation to S. aureus bacteria, of the scaffolds incorporated with antimicrobial agents revealed that the studied samples had little inhibitory action. It is understood that it is not enough to just incorporate an agent with a high antimicrobial capacity into the scaffold, but to understand how this agent will be incorporated into the scaffold and whether this incorporation will leave it in contact with the microorganism during the antimicrobial activity test. Therefore, it was possible to obtain β-TCP scaffolds, incorporate them with antimicrobial agents and although they have little inhibitory action, it was possible to observe the relevance of the research and guide the studies for future work.