Navegando por Assunto "Chitosan"

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    Antitumor activity of membranes associated with Acmella oleracea extract
    (Associação Brasileira de Divulgação Científica) Silva, Carlos Augusto Priante da; Godoi, Bruno Henrique; Menegon, Renato Farina; Silva, Newton Soares da; Soares, Cristina Pacheco
    Epithelial cancers, such as epidermoid cancer and some adenocarcinomas, affect surface areas that are generally more accessible to various treatments. However, this group of tumor cells has an aggressive behavior, leading to a high annual mortality rate. The development of a biomaterial that is non-invasive, can kill tumor cells, and prevent opportunistic infections is the basis for the treatment for this type of cancer. Therefore, the objective of this study was to develop a biomaterial from chitosan and A. oleracea extracts that exhibits cytotoxic action against the HEp-2 tumor cell line. Dried crude 90% ethanol extracts were obtained through ultrasound-assisted maceration, followed by liquid-liquid extraction to yield the butanol fraction. From these extracts, chitosan membranes were developed and evaluated for their antitumor activity against HEp-2 using viability tests with crystal violet and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, in addition to a wound healing test. The cytotoxic assays indicated a significant reduction in cell density and mitochondrial activity, especially at the concentration of 1000 mg/mL of crude extract. The butanol fraction had minimal effects on mitochondrial activity. The wound healing test demonstrated that the biomaterial and extract prevented closure of the wound created in the cell monolayer within 48 h of incubation and caused changes in cell morphology. In view of this, we concluded that a chitosan membrane associated with a 90% ethanol extract of Acmella oleracea exhibited cytotoxic activity is a potential alternative treatment for superficial cancers.
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    Biomineralization induced by chitosan and collagen‐based materials with fluoride for dentin coverage: Chemical and morphological analysis
    (Wiley) Nahórny, Sidnei; Oliveira, Ivone Regina de; Soares, Luís Eduardo Silva
    The prevention and treatment of erosive tooth wear are becoming increasingly important due to its increasing prevalence. The use of natural solutions to modify dental surfaces has become an area of research. Organic materials such as chitosan and hydrolyzed collagen may be a promising option to treat dentin. This in vitro study aimed to evaluate the influence of chitosan or hydrolyzed collagen, alone or com- bined with acidulated phosphate fluoride (APF) gel, on the composition and morphol- ogy of dentin after erosion. Bovine dentin samples were prepared (n = 84) and treated with artificial saliva (AS, negative control); APF gel (F, positive control); chitosan solution (Chi); hydrolyzed collagen solution (Col); fluoride/chitosan composi- tion (F_Chi); and fluoride/hydrolyzed collagen composition (F_Col). Erosive cycles (six cycles of immersion in orange juice for 1 min, followed by immersion in AS for 1 hr) were performed. The materials were characterized by their morphology, composition, and particle size distribution. Micro-energy dispersive X-ray fluorescence spectros- copy and scanning electron were used to evaluate the dentin's inorganic chemical composition and morphology. The F_Col and F groups had a reduction in calcium loss by 17 and 26%, respectively (p < .001). Both of these groups still had a covering layer of agglomerates at the dentin surface after the erosive cycles. The fluoridated chitosan or collagen solutions improved the dentin resistance to erosion as a novel hybrid-fluoride-based material approach to provide surface protection from erosion.
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    Combined morphological-compositional analysis of the interaction of collagen and chitosan based-materials with demineralized bovine dentin
    (Brazilian Journals Publicações de Periódicos) Nahórny, Sidnei; Oliveira, Ivone Regina de; Soares, Luís Eduardo Silva
    Treatments to promote the biomineralization of dentin are the focus of much research with different materials and processes. Biomineralization is a process mediated by an organic matrix in which organic macromolecules act as models for the nucleation and growth of mineral crystals to form hierarchically ordered hybrid materials, such as bones or teeth. This study describes the application of novel materials based on collagen and chitosan aimed to protect the dentin from erosive conditions. The dentin morphology of the bovine teeth treated with these materials was visualized using scanning electron microscopy (SEM). In additions, it was possible to confirm the data by analyzing the distribution of inorganic content of dentin by micro energy-dispersive X-ray fluorescence spectrometry (µ-EDXRF). The association of analytical techniques demonstrated greater surface coverage for the chitosan-fluoride followed by the hydrolyzed collagen. Both materials are promising for the application of dentin coverage in dentistry.