Engenharia Biomédica

URI permanente para esta coleçãohttps://repositorioacademico.universidadebrasil.edu.br/handle/123456789/915

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Avaliação da atividade antimicrobiana da terapia fotodinâmica no tratamento da microbiota bucal
(Universidade Brasil, 2022) Moreti, Lucieni Cristina Trovati; Tim, Carla Roberta; Assis, Lívia
Photodynamic Therapy (PDT) is based on the interaction of light with a photosensitizer capable of promoting microbial destruction. In the present work, the antimicrobial activity of aPDT was evaluated in vitro using two photosensitizers (phenothiazine and annatto) and different times of treatment of oral biofilm, as well as microorganisms were identified and bacterial resistance and sensitivity to certain antibiotics were evaluated. For this, antimicrobial samples of oral biofilm (tongue) were collected from patients without and with pneumonia admitted to the ICU, who were intubated for a period of at least 24 and at most 48 hours, using swabs soaked in saline solution (NaCl 0.5 %) and later cultivated in agarized media. Samples from patients without pneumonia were randomized into: non-pneumonia control group (NP - C): microorganisms without intervention; non-pneumonia chlorhexidine group (NP - CLX): used 0.12% chlorhexidine; non-pneumonia group red PDT (NP - PDTV): used aPDT using 630 nm LED and phenothiazine photosensitizer; non-pneumonia blue PDT group (NP - PDTA): used the use of aPDT using 450 nm LED and annatto photosensitizer, both using a single application. And control pneumonia group (P - C): microorganisms without intervention; group with chlorhexidine pneumonia (P ¬ CLX): used 0.12% chlorhexidine; group with red PDT pneumonia (P - PDTV): used the use of PDT using 630 nm LED and phenothiazine photosensitizer; group with blue PDT pneumonia (P - PDTA): used the use of PDT using 450 nm LED and annatto photosensitizer. They were irradiated with the following parameters: red LED (λ630 ± 10ηm) or blue LED (λ450 ± 10ηm), both at 100 mW power and treated for 150, 300 or 600 seconds. After 24 hours, colony forming units (CFU) and antibiogram were counted. The results showed that the NP – CLX and P – CLX groups promoted total CFU reduction. The PDT groups in oral biofilm without and with pneumonia showed that the CFU reduction was dependent on the treatment time, being better at 600 seconds of treatment. Through the genetic code, Gram-negative microorganisms such as Pseudomonas aeruginosa and Gram-positive microorganisms such as Bhargavaea sp., Desemzia incerta, Kocuria rosea, Micrococcus sp. ,Micrococcus luteus, Agrococcus carbonis, Microbacterium paraoxydans, Corynebacterium sp., Dietzia aurantiaca, Enterococcus faecalis and Staphylococcus saprophyticus.The antibiogram performed evaluated the multiple antimicrobial resistance index (IRMA) characterizing multiresistance to all. Conclusion: Despite being composed of multidrug-resistant microorganisms, aPDT showed potential for the treatment of oral biofilm in patients with and without pneumonia.
Efeitos da fotobiomodulação associada ou não ao Biopolímero de Fibrina Heterólogo no processo de reparo tecidual de lesões cutâneas de ratos diabéticos
(Universidade Brasil, 2021) Alexandria, Francisco Eugênio Deusdará de; Tim, Carla Roberta; Assis, Lívia
Membranas de quitosana associada a cúrcuma: produção, caracterização e avaliação da biocompatibilidade e efeitos antimicrobianos
(Universidade Brasil, 2024) Macedo, Daniela Bezerra; Assis, Lívia; Pavinatto, Adriana
Skin wounds cause pain, functional impairment and quality of life and are associated with significant economic impact. Chitosan and turmeric have properties that have the potential to promote the repair of skin wounds. However, the relationship between medium molar mass chitosan associated or not with turmeric, as well as the physicochemical properties and biological effects have not yet been elucidated. Thus, the objective of the present study was to produce, characterize and evaluate, in vitro, the cytotoxicity of a membrane based on medium molar mass chitosan associated or not with turmeric in a fibroblast line (L929), as well as the antimicrobial potential for Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Three chitosan based membranes of medium molar mass were produced using the casting (solvent evaporation) thin film formation technique: 1% chitosan-based membrane (m/v; QM); chitosan associated with 30% glycerol (m/m in relation to the mass of chitosan; QMG); chitosan associated with 30% glycerol and 1.5% turmeric (m/m in relation to the mass of chitosan; QMGC). To characterize the physicochemical and morphological properties of the membranes, infrared absorption spectroscopy (FTIR), contact angle and thickness measurements were used. To evaluate cell viability/cytotoxicity, L929 cells were used at a concentration of 1x104 using the alamarBlue® and Picrogreen assay; To evaluate the antimicrobial potential, strains of Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli were used at a concentration of 1 x 108 by evaluating the inhibition halo. The results show that all membranes were sustainable, homogeneous and flexible, with the QMG and QMGC membranes being the most flexible and most hydrophilic compared to the QM membrane. Vibrational bands were observed for chemical groups of chitosan and glycerol in all membranes. Regarding the evaluation of cytotoxicity, all membranes showed higher values of metabolic activity/viability, as well as a greater proliferation of fibroblast cells in the experimental period of 72 hours when compared to 24 hours of culture. Furthermore, all membranes presented an inhibition halo to the tested microorganisms, with the QMGC membrane promoting the greatest inhibition halo. With the results obtained in the present study, it is possible to confirm the reparative potential of chitosan-based membranes of medium molar mass, as well as their antimicrobial potential, with emphasis on the membrane associated with turmeric. However, further studies are needed to elucidate the use of these membranes as potential biomaterials for bioactive wound dressings.