93 research outputs found
Physicochemical and biological characterization of chitosan-microRNA nanocomplexes for gene delivery to MCF-7 breast cancer cells
Cancer gene therapy requires the design of non-viral vectors that carry genetic material and selectively deliver it with minimal toxicity. Non-viral vectors based on cationic natural polymers can form electrostatic complexes with negatively-charged polynucleotides such as microRNAs (miRNAs). Here we investigated the physicochemical/biophysical properties of chitosanâhsa-miRNA-145 (CSâmiRNA) nanocomplexes and the biological responses of MCF-7 breast cancer cells cultured in vitro. Self-assembled CSâmiRNA nanocomplexes were produced with a range of (+/â) charge ratios (from 0.6 to 8) using chitosans with various degrees of acetylation and molecular weight. The Z-average particle diameter of the complexes was <200ânm. The surface charge increased with increasing amount of chitosan. We observed that chitosan induces the base-stacking of miRNA in a concentration dependent manner. Surface plasmon resonance spectroscopy shows that complexes formed by low degree of acetylation chitosans are highly stable, regardless of the molecular weight. We found no evidence that these complexes were cytotoxic towards MCF-7 cells. Furthermore, CSâmiRNA nanocomplexes with degree of acetylation 12% and 29% were biologically active, showing successful downregulation of target mRNA expression in MCF-7 cells. Our data, therefore, shows that CSâmiRNA complexes offer a promising non-viral platform for breast cancer gene therapy
Caracterização quĂmica e efeito cicatrizante de quitosana, com baixos valores de massa molar e grau de acetilação, em lesĂ”es cutĂąneas
Wet-spinning and applications of functional fibers based on chitin and chitosan
cited By 20International audienceA series of novel human-made functional fibers (biofibers) based on chitin and chitosan are prepared by the wet-spinning and the post chemical modification of chitosan fiber. The wet-spinning gives rise to a series of biofibers: chitin, chitosan, chitin-cellulose, chitosan-cellulose, chitin-silk fibroin, chitin-glycosaminoglycans, chitin-cellulose-silk fibroin, chitosan-tropocollagen, and chitin-cellulose-silk fibroin. The post chemical modification of chitosan fiber gives rise to a series of chemically modified fibers: N-acylchitosans, N-arylidene- and N-alkylidene-chitosans, N-acetylchitosan (chitin)-tropocollagen, and chitosan-transition metal complexes. Some of the current and potential applications of these biofibers are described
Solid state NMR for determination of degree of acetylation of chitin and chitosan
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Overview on structural characterization of chitosan molecules in relation with their behavior in solution
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An infrared investigation in relation with chitin and chitosan characterization
cited By 649International audienceThe use of infrared spectroscopy for characterization of the composition of chitin and chitosan covering the entire range of degree of acetylation (DA) and a wide variety of raw materials is examined further. The ratio of absorbance bands selected was calibrated using 1H liquid and 13C CP-MAS solid-state NMR as absolute techniques. IR spectra of the structural units of these polymers validated the choice of baselines and characteristic bands. The bands at 1650 and 1320 cm-1 were chosen to measure the DA. As internal reference, the intensities at 3450 and 1420 cm-1 were evaluated. The absorption band ratios involving the reference at 3450 cm-1 had poorer fit.. The absorption ratio A1320/A1420 shows superior agreement between the absolute and estimated DA-values (DA% = 31.92A1320/A1420 - 12.20; r = 0.990). © 2001 Elsevier Science Ltd
DĂ©lĂ©gation mĂ©dicale vers un(e) spĂ©cialiste en activitĂ© physique adaptĂ©e (APA)â: un projet pilote
Les mĂ©decins de famille ont un rĂŽle clĂ© pour la promotion de lâactivitĂ© physique, en particulier pour identifier et conseiller des personnes sĂ©dentaires. Certains patients pourraient bĂ©nĂ©ficier dâun accompagnement individuel plus intensif. Les offres dâactivitĂ© physique dans la communautĂ© ne sont pas toujours connues des mĂ©decins. Dans une Ă©tude pilote, nous avons testĂ© et adaptĂ© la dĂ©lĂ©gation de patients par des mĂ©decins de famille vers des spĂ©cialistes en activitĂ© physique adaptĂ©e (APAs). Les APAs sont formĂ©s Ă Ă©valuer et accompagner des personnes vers des activitĂ©s physiques adaptĂ©es Ă leurs besoins et pathologies et dâainsi permettre une augmentation du niveau dâactivitĂ© physique. Les donnĂ©es pilotes suggĂšrent que, si peu de patients ont Ă©tĂ© orientĂ©s vers les APAs, les mĂ©decins apprĂ©cient la possibilitĂ© de collaborer avec un APAs
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