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 chitosan–hsa-miRNA-145 (CS–miRNA) nanocomplexes and the biological responses of MCF-7 breast cancer cells cultured in vitro. Self-assembled CS–miRNA nanocomplexes were produced with a range of (+/−) 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 <200 nm. 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, CS–miRNA 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 CS–miRNA complexes offer a promising non-viral platform for breast cancer gene therapy

Characterization of chitosan by steric exclusion chromatography

International audienc

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

International audienc

Overview on structural characterization of chitosan molecules in relation with their behavior in solution

International audienc

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

Délégation médicale vers un(e) spécialiste en activité physique adaptée (APA) : un projet pilote

Les médecins de famille ont un rôle clé pour la promotion de l’activité physique, en particulier pour identifier et conseiller des personnes sédentaires. Certains patients pourraient bénéficier d’un accompagnement individuel plus intensif. Les offres d’activité physique dans la communauté ne sont pas toujours connues des médecins. Dans une étude pilote, nous avons testé et adapté la délégation de patients par des médecins de famille vers des spécialistes en activité physique adaptée (APAs). Les APAs sont formés à évaluer et accompagner des personnes vers des activités physiques adaptées à leurs besoins et pathologies et d’ainsi permettre une augmentation du niveau d’activité physique. Les données pilotes suggèrent que, si peu de patients ont été orientés vers les APAs, les médecins apprécient la possibilité de collaborer avec un APAs