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Jacques Desbrieres - One of the best experts on this subject based on the ideXlab platform.

  • Viscosity of Semiflexible Chitosan Solutions: Influence of Concentration, Temperature, and Role of Intermolecular Interactions
    Biomacromolecules, 2002
    Co-Authors: Jacques Desbrieres
    Abstract:

    The influence of polymer concentration and temperature on the rheological behavior of Chitosan Solution was studied. The threshold concentrations for the different viscometric regimes were determined and the different power laws exponents were calculated and compared with those predicted from models. Different observations and the high values of these exponents within the high concentration region lead to consideration of the presence of intermolecular interactions as soon as the polymer concentration is larger than the overlap concentration. The activation energy was determined as a function of the polymer concentration, and its evolution was compared with theoretical predictions. A gel-sol transition was demonstrated at high concentrations.

  • Viscosity of semiflexible Chitosan Solutions: Influence of concentration, temperature, and role of intermolecular interactions
    Biomacromolecules, 2002
    Co-Authors: Jacques Desbrieres
    Abstract:

    The influence of polymer concentration and temperature on the rheological behavior of Chitosan Solution was studied. The threshold concentrations for the different viscometric regimes were determined and the different power laws exponents were calculated and compared with those predicted from models. Different observations and the high values of these exponents within the high concentration region lead to consideration of the presence of intermolecular as soon as the polymer concentration is larger than the overlap concentration. The activation energy was determined as a function of the polymer concentration, and its evolution was compared with theoretical predictions. A gel-sol transition was demonstrated at high concentrations.

Renata Fonseca Vianna Lopez - One of the best experts on this subject based on the ideXlab platform.

  • enhancing and sustaining the topical ocular delivery of fluconazole using Chitosan Solution and poloxamer Chitosan in situ forming gel
    European Journal of Pharmaceutics and Biopharmaceutics, 2011
    Co-Authors: Tais Gratieri, Guilherme M. Gelfuso, Osvaldo De Freitas, Eduardo Rocha, Renata Fonseca Vianna Lopez
    Abstract:

    Fungal keratitis is a serious disease that can lead to loss of vision. Unfortunately, current therapeutic options often result in poor bioavailability of antifungal agents due to protective mechanisms of the eye. The aim of this work was to evaluate the potential of a Chitosan Solution as well as an in situ gel-forming system comprised of poloxamer/Chitosan as vehicles for enhanced corneal permeation and sustained release of fluconazole (FLU). For this, in vitro release and ex vivo corneal permeation experiments were carried out as a function of Chitosan concentration from formulation containing the Chitosan alone and combined with the thermosensitive polymer, poloxamer. Microdialysis was employed in a rabbit model to evaluate the in vivo performance of the formulations. The in vitro release studies showed the sustained release of FLU from the poloxamer/Chitosan formulation. Ex vivo permeation studies across porcine cornea demonstrated that the formulations studied have a permeation-enhancing effect that is independent of Chitosan concentration in the range from 0.5 to 1.5% w/w. The Chitosan Solutions alone showed the greatest ex vivo drug permeation; however, the poloxamer/Chitosan formulation presented similar in vivo performance than the Chitosan Solution at 1.0%; both formulations showed sustained release and about 3.5-fold greater total amount of FLU permeated when compared to simple aqueous Solutions of the drug. In conclusion, it was demonstrated that both the in situ gelling formulation evaluated and the Chitosan Solution are viable alternatives to enhance ocular bioavailability in the treatment of fungal keratitis.

  • Enhancing and sustaining the topical ocular delivery of fluconazole using Chitosan Solution and poloxamer/Chitosan in situ forming gel.
    European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V, 2011
    Co-Authors: Tais Gratieri, Guilherme M. Gelfuso, Osvaldo De Freitas, Eduardo Rocha, Renata Fonseca Vianna Lopez
    Abstract:

    Fungal keratitis is a serious disease that can lead to loss of vision. Unfortunately, current therapeutic options often result in poor bioavailability of antifungal agents due to protective mechanisms of the eye. The aim of this work was to evaluate the potential of a Chitosan Solution as well as an in situ gel-forming system comprised of poloxamer/Chitosan as vehicles for enhanced corneal permeation and sustained release of fluconazole (FLU). For this, in vitro release and ex vivo corneal permeation experiments were carried out as a function of Chitosan concentration from formulation containing the Chitosan alone and combined with the thermosensitive polymer, poloxamer. Microdialysis was employed in a rabbit model to evaluate the in vivo performance of the formulations. The in vitro release studies showed the sustained release of FLU from the poloxamer/Chitosan formulation. Ex vivo permeation studies across porcine cornea demonstrated that the formulations studied have a permeation-enhancing effect that is independent of Chitosan concentration in the range from 0.5 to 1.5% w/w. The Chitosan Solutions alone showed the greatest ex vivo drug permeation; however, the poloxamer/Chitosan formulation presented similar in vivo performance than the Chitosan Solution at 1.0%; both formulations showed sustained release and about 3.5-fold greater total amount of FLU permeated when compared to simple aqueous Solutions of the drug. In conclusion, it was demonstrated that both the in situ gelling formulation evaluated and the Chitosan Solution are viable alternatives to enhance ocular bioavailability in the treatment of fungal keratitis.

Tais Gratieri - One of the best experts on this subject based on the ideXlab platform.

  • enhancing and sustaining the topical ocular delivery of fluconazole using Chitosan Solution and poloxamer Chitosan in situ forming gel
    European Journal of Pharmaceutics and Biopharmaceutics, 2011
    Co-Authors: Tais Gratieri, Guilherme M. Gelfuso, Osvaldo De Freitas, Eduardo Rocha, Renata Fonseca Vianna Lopez
    Abstract:

    Fungal keratitis is a serious disease that can lead to loss of vision. Unfortunately, current therapeutic options often result in poor bioavailability of antifungal agents due to protective mechanisms of the eye. The aim of this work was to evaluate the potential of a Chitosan Solution as well as an in situ gel-forming system comprised of poloxamer/Chitosan as vehicles for enhanced corneal permeation and sustained release of fluconazole (FLU). For this, in vitro release and ex vivo corneal permeation experiments were carried out as a function of Chitosan concentration from formulation containing the Chitosan alone and combined with the thermosensitive polymer, poloxamer. Microdialysis was employed in a rabbit model to evaluate the in vivo performance of the formulations. The in vitro release studies showed the sustained release of FLU from the poloxamer/Chitosan formulation. Ex vivo permeation studies across porcine cornea demonstrated that the formulations studied have a permeation-enhancing effect that is independent of Chitosan concentration in the range from 0.5 to 1.5% w/w. The Chitosan Solutions alone showed the greatest ex vivo drug permeation; however, the poloxamer/Chitosan formulation presented similar in vivo performance than the Chitosan Solution at 1.0%; both formulations showed sustained release and about 3.5-fold greater total amount of FLU permeated when compared to simple aqueous Solutions of the drug. In conclusion, it was demonstrated that both the in situ gelling formulation evaluated and the Chitosan Solution are viable alternatives to enhance ocular bioavailability in the treatment of fungal keratitis.

  • Enhancing and sustaining the topical ocular delivery of fluconazole using Chitosan Solution and poloxamer/Chitosan in situ forming gel.
    European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V, 2011
    Co-Authors: Tais Gratieri, Guilherme M. Gelfuso, Osvaldo De Freitas, Eduardo Rocha, Renata Fonseca Vianna Lopez
    Abstract:

    Fungal keratitis is a serious disease that can lead to loss of vision. Unfortunately, current therapeutic options often result in poor bioavailability of antifungal agents due to protective mechanisms of the eye. The aim of this work was to evaluate the potential of a Chitosan Solution as well as an in situ gel-forming system comprised of poloxamer/Chitosan as vehicles for enhanced corneal permeation and sustained release of fluconazole (FLU). For this, in vitro release and ex vivo corneal permeation experiments were carried out as a function of Chitosan concentration from formulation containing the Chitosan alone and combined with the thermosensitive polymer, poloxamer. Microdialysis was employed in a rabbit model to evaluate the in vivo performance of the formulations. The in vitro release studies showed the sustained release of FLU from the poloxamer/Chitosan formulation. Ex vivo permeation studies across porcine cornea demonstrated that the formulations studied have a permeation-enhancing effect that is independent of Chitosan concentration in the range from 0.5 to 1.5% w/w. The Chitosan Solutions alone showed the greatest ex vivo drug permeation; however, the poloxamer/Chitosan formulation presented similar in vivo performance than the Chitosan Solution at 1.0%; both formulations showed sustained release and about 3.5-fold greater total amount of FLU permeated when compared to simple aqueous Solutions of the drug. In conclusion, it was demonstrated that both the in situ gelling formulation evaluated and the Chitosan Solution are viable alternatives to enhance ocular bioavailability in the treatment of fungal keratitis.

Suwabun Chirachanchai - One of the best experts on this subject based on the ideXlab platform.

  • Silver nanoparticles dispersing in Chitosan Solution: Preparation by γ-ray irradiation and their antimicrobial activities
    Materials Chemistry and Physics, 2009
    Co-Authors: Rangrong Yoksan, Suwabun Chirachanchai
    Abstract:

    Abstract Silver nanoparticles were prepared by γ-ray irradiation–reduction under simple conditions, i.e., air atmosphere, using Chitosan as a stabilizer. The nanoparticles were spherical with an average size of 7–30 nm as observed from TEM. The size decreased when Chitosan concentration increased, while it increased with increasing γ-ray dose and initial silver nitrate content. The obtained silver nanoparticles dispersed in a 0.5% (w/v) γ-ray irradiated Chitosan–aqueous acetic acid Solution were stable for more than 3 months without tendency to precipitate. The silver nanoparticles exhibited antimicrobial activities against Escherichia coli and Staphylococcus aureus. The results suggest that silver nanoparticles dispersed in Chitosan Solution can be directly applied in antimicrobial fields, including antimicrobial food packaging and biomedical applications.

Fatih Ozogul - One of the best experts on this subject based on the ideXlab platform.

  • Chitosan role for shelf-life extension of seafood
    Environmental Chemistry Letters, 2019
    Co-Authors: Piotr Kulawik, Ewelina Jamróz, Fatih Ozogul
    Abstract:

    Chitosan, a deacetylated derivative of chitin, has many functional properties that can be used for processing, preservation and as food additive. Chitosan application can be done by edible coatings, direct addition to the batter, and tumbling in the Chitosan Solution. Chitosan exhibits antioxidant and antimicrobial properties. Here we review applications of Chitosan in seafood products and effects on the shelf life of the stored product. Chitosan treatment is effective against two main spoilage factors of seafood: increased oxidation and microbiological spoilage. Chitosan treatment avoids the decrease of sensory scores during storage, and prolongs shelf life of Chitosan-treated seafood products.