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Papers by Sébastien Malaise

Research paper thumbnail of Polyelectrolyte complexes via desalting mixtures of hyaluronic acid and chitosan—Physicochemical study and structural analysis

Carbohydrate Polymers, Dec 1, 2016

Highlights:  The controlled assembly of chitosan and hyaluronic acid was achieved.  Physicochem... more Highlights:  The controlled assembly of chitosan and hyaluronic acid was achieved.  Physicochemical parameters of chitosan and the influence on the PECs were investigated.  Different physical forms as colloidal suspensions and coacervates were obtained.  The nanostructure of the different hyaluronic/ chitosan complexes was investigated.

Research paper thumbnail of Small Diameter Vascular Substitues Based on Physical Chitosan Hydrogels : Proof of Concept

Le chitosane presente des proprietes biologiques (biocompatibilite, bioresorbabilite, bioactivite... more Le chitosane presente des proprietes biologiques (biocompatibilite, bioresorbabilite, bioactivite) idealement adaptees a des applications en ingenierie tissulaire. Dans cette etude partenariale (Programme ANR TECSAN 2010 ChitoArt), nous avons travaille a l'elaboration d'hydrogels physiques de chitosane a proprietes physico-chimiques et biologiques variees et controlees, sans utilisation d'agents de reticulation externes. Ces hydrogels sont envisages sous forme de tube mono ou pluri-membranaires pour une utilisation en tant que substituts vasculaires de petit diametre (<6mm). En effet, l'ingenierie vasculaire presente, encore de nos jours, de nombreuses limitations lorsqu'il est question de vaisseaux de petits calibres. Notre demarche consiste en la modulation des parametres structuraux (degre d'acetylation, masse molaire) et environnementaux (concentration du bain de gelification, du collodion) intervenants dans le procede d'elaboration des hydrogels pour atteindre les criteres physiques, biologiques et mecaniques compatibles avec cette application. L'etude morphologique des hydrogels par Cryo-Microscopie Electronique a Balayage (Cryo-MEB), via une methode de preparation originale a permis une meilleure comprehension de l'organisation micro-structurale et multi-echelle des hydrogels de chitosane. Cette approche fondamentale a ete couplee a une evaluation in vivo des proprietes biologiques des hydrogels ainsi qu'a des caracterisations mecaniques des substituts vasculaires. En particulier, l'evaluation de la suturabilite de nos substituts a mene au developpement d'une formulation donnant lieu a des hydrogels physiques de chitosane suturables ayant fait l'objet d'un depot de brevet (N° de depot FR1363099). Le controle et la modulation des parametres d'elaboration des hydrogels ont permis l'obtention de substituts vasculaire cellularisables et respectant les exigences (suture, compliance, resistance a l'eclatement) concernant leur implantation in vivo

Research paper thumbnail of ヒアルロン酸の混合物の脱塩による高分子電解質錯体及びキトサン物理化学的研究と構造解析【Powered by NICT】

Research paper thumbnail of Polyelectrolyte complexes via desalting mixtures of hyaluronic acid and chitosan—Physicochemical study and structural analysis

Carbohydrate Polymers, 2016

Highlights:  The controlled assembly of chitosan and hyaluronic acid was achieved.  Physicochem... more Highlights:  The controlled assembly of chitosan and hyaluronic acid was achieved.  Physicochemical parameters of chitosan and the influence on the PECs were investigated.  Different physical forms as colloidal suspensions and coacervates were obtained.  The nanostructure of the different hyaluronic/ chitosan complexes was investigated.

Research paper thumbnail of Physicochemical modulation of chitosan-based hydrogels induces different biological responses: Interest for tissue engineering

Journal of Biomedical Materials Research Part A, 2013

Polysaccharide-based hydrogels are remarkable materials for the development of tissue engineering... more Polysaccharide-based hydrogels are remarkable materials for the development of tissue engineering strategies as they meet several critical requirements for such applications and they may partly mimic the extracellular matrix. Chitosan is widely envisioned as hydrogel in biomedical fields for its bioresorbability, biocompatibility, and fungistatic and bacteriostatic properties. In this study, we report that the modulation of the polymer concentration, the degree of acetylation, the gelation processes [or neutralization routes (NR)] in the preparation of different chitosan-based hydrogels lead to substantially and significantly different biological responses. We show that it is possible to tune the physicochemical characteristics, mechanical properties, and biological responses of such matrices. Physical hydrogels prepared from highly acetylated chitosan were softer, degraded quickly in vivo, and were not suitable for in vitro culture of human mesenchymal stem and progenitor derived endothelial cells. In contrast, for a same chitosan concentration and obtained by the same processing route, a low degree of acetylation chitosan hydrogel provided a more elastic material, better cell adhesion on its surface and tissue regeneration, and restored tissue neo-vascularization as well. This work offers promising and innovative perspectives for the design of hydrogel materials with tunable properties for tissue engineering and regenerative medicine. V

Research paper thumbnail of Small Diameter Vascular Substitues Based on Physical Chitosan Hydrogels : Proof of Concept

Le chitosane presente des proprietes biologiques (biocompatibilite, bioresorbabilite, bioactivite... more Le chitosane presente des proprietes biologiques (biocompatibilite, bioresorbabilite, bioactivite) idealement adaptees a des applications en ingenierie tissulaire. Dans cette etude partenariale (Programme ANR TECSAN 2010 ChitoArt), nous avons travaille a l'elaboration d'hydrogels physiques de chitosane a proprietes physico-chimiques et biologiques variees et controlees, sans utilisation d'agents de reticulation externes. Ces hydrogels sont envisages sous forme de tube mono ou pluri-membranaires pour une utilisation en tant que substituts vasculaires de petit diametre (<6mm). En effet, l'ingenierie vasculaire presente, encore de nos jours, de nombreuses limitations lorsqu'il est question de vaisseaux de petits calibres. Notre demarche consiste en la modulation des parametres structuraux (degre d'acetylation, masse molaire) et environnementaux (concentration du bain de gelification, du collodion) intervenants dans le procede d'elaboration des hydrogels p...

Research paper thumbnail of Highly stretchable hydrogels from complex coacervation of natural polyelectrolytes

Soft Matter

Polyelectrolyte complexation between chitosan and hyaluronic acid at pH between 2 and 3 leads to ... more Polyelectrolyte complexation between chitosan and hyaluronic acid at pH between 2 and 3 leads to highly stretchable hydrogels.

Research paper thumbnail of In Vitro Mechanical Property Evaluation of Chitosan-Based Hydrogels Intended for Vascular Graft Development

Journal of cardiovascular translational research, Jan 31, 2017

Vascular grafts made of synthetic polymers perform poorly in cardiac and peripheral bypass applic... more Vascular grafts made of synthetic polymers perform poorly in cardiac and peripheral bypass applications. In these applications, chitosan-based materials can be produced and shaped to provide a novel scaffold for vascular tissue engineering. The goal of this study was to evaluate in vitro the mechanical properties of a novel chitosan formulation to assess its potential for this scaffold. Two chitosan-based hydrogel tubes were produced by modulating chitosan concentration. Based on the standard ISO 7198:1998, the hydrogel tubes were characterized in vitro in terms of suture retention strength, tensile strength, compliance, and burst pressure. By increasing chitosan concentration, suture retention value increased to reach 1.1 N; average burst strength and elastic moduli also increased significantly. The compliance seemed to exhibit a low value for chitosan tubes of high concentration. By modulating chitosan concentration, we produced scaffolds with suitable mechanical properties to be ...

Research paper thumbnail of Biosynthetic Multi-hydrogels for tissue engineering

Research paper thumbnail of Bioresorption mechanisms of Chitosan Physical Hydrogels: A Scanning Electron Microscopy Study

Materials Science and Engineering: C, 2014

Tissue-engineered biodegradable medical devices are widely studied and systems must present suita... more Tissue-engineered biodegradable medical devices are widely studied and systems must present suitable balance between versatility and elaboration simplicity. In this work, we aim at illustrating that such equilibrium can be found by processing chitosan physical hydrogels without external cross-linker. Chitosan concentration, degree of acetylation, solvent composition, and neutralization route were modulated in order to obtain hydrogels exhibiting different physico-chemical properties. The resulting in vivo biological response was investigated by Scanning Electron Microscopy. "Soft" hydrogels were obtained from chitosan of high degree of acetylation (35%) and by the neutralization with gaseous ammonia of a chitosan acetate aqueous solutions presenting low polymer concentration (Cp=1.6% w/w). "Harder" hydrogels were obtained from chitosan with lower degree of acetylation (5%) and after neutralization in sodium hydroxide bath (1M) of hydro-alcoholic chitosan solutions (50/50 w/w water/1,2-propanediol) with a polymer concentration of 2.5% w/w. Soft and hard hydrogels exhibited bioresorption times from below 10 days to higher than 60 days, respectively. We also evidenced that cell colonization and neovascularization mechanisms depend on the hydrogel-aggregated structure that is controlled by elaboration conditions and possibly in relation with mechanical properties. Specific processing conditions induced micron-range capillaries formation, which can be assimilated to colonization channels, also acting on the resorption scenario.

Research paper thumbnail of Bioresorption mechanisms of Chitosan Physical Hydrogels: A Scanning Electron Microscopy Study

Materials Science and Engineering: C, 2014

Tissue-engineered biodegradable medical devices are widely studied and systems must present suita... more Tissue-engineered biodegradable medical devices are widely studied and systems must present suitable balance between versatility and elaboration simplicity. In this work, we aim at illustrating that such equilibrium can be found by processing chitosan physical hydrogels without external cross-linker. Chitosan concentration, degree of acetylation, solvent composition, and neutralization route were modulated in order to obtain hydrogels exhibiting different physico-chemical properties. The resulting in vivo biological response was investigated by scanning electron microscopy. &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Soft&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; hydrogels were obtained from chitosan of high degree of acetylation (35%) and by the neutralization with gaseous ammonia of a chitosan acetate aqueous solutions presenting low polymer concentration (Cp=1.6% w/w). &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Harder&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; hydrogels were obtained from chitosan with lower degree of acetylation (5%) and after neutralization in sodium hydroxide bath (1M) of hydro-alcoholic chitosan solutions (50/50 w/w water/1,2-propanediol) with a polymer concentration of 2.5% w/w. Soft and hard hydrogels exhibited bioresorption times from below 10 days to higher than 60 days, respectively. We also evidenced that cell colonization and neo-vascularization mechanisms depend on the hydrogel-aggregated structure that is controlled by elaboration conditions and possibly in relation with mechanical properties. Specific processing conditions induced micron-range capillary formation, which can be assimilated to colonization channels, also acting on the resorption scenario.

Research paper thumbnail of Liposome-loaded chitosan physical hydrogel: Toward a promising delayed-release biosystem

Carbohydrate Polymers, 2015

This work deals with the elaboration of an original biosystem in view of its application as drug ... more This work deals with the elaboration of an original biosystem in view of its application as drug delayed-release device in biomedical area. This innovative &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;hybrid&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; system is composed of phosphatidylcholine liposomes entrapped within a chitosan physical hydrogel (only constituted of polymer and water). To this end, pre-formed liposomes were suspended into chitosan solutions, and the polymer gelation process was subsequently carried out following particular experimental conditions. This liposome incorporation did absolutely not prevent the gel formation as shown by rheological properties of the resulting tridimensional matrix. The presence of liposomes within the hydrogel was confirmed by fluorescence and cryo-scanning electron microscopies. Then, the expected concept of delayed-release of this &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;hybrid&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; system was proved using a model water soluble molecule (carboxyfluorescein, CF) encapsulated in liposomes, themselves incorporated into the chitosan hydrogel. The CF release was assayed after repeated and intensive washings of hydrogels, and was found to be higher in the CF-in-hydrogel systems in comparison with the CF-in-liposomes-in-hydrogel ones, demonstrating a CF delayed-release thanks to lipid vesicles.

Research paper thumbnail of Polyelectrolyte complexes via desalting mixtures of hyaluronic acid and chitosan—Physicochemical study and structural analysis

Carbohydrate Polymers, Dec 1, 2016

Highlights:  The controlled assembly of chitosan and hyaluronic acid was achieved.  Physicochem... more Highlights:  The controlled assembly of chitosan and hyaluronic acid was achieved.  Physicochemical parameters of chitosan and the influence on the PECs were investigated.  Different physical forms as colloidal suspensions and coacervates were obtained.  The nanostructure of the different hyaluronic/ chitosan complexes was investigated.

Research paper thumbnail of Small Diameter Vascular Substitues Based on Physical Chitosan Hydrogels : Proof of Concept

Le chitosane presente des proprietes biologiques (biocompatibilite, bioresorbabilite, bioactivite... more Le chitosane presente des proprietes biologiques (biocompatibilite, bioresorbabilite, bioactivite) idealement adaptees a des applications en ingenierie tissulaire. Dans cette etude partenariale (Programme ANR TECSAN 2010 ChitoArt), nous avons travaille a l'elaboration d'hydrogels physiques de chitosane a proprietes physico-chimiques et biologiques variees et controlees, sans utilisation d'agents de reticulation externes. Ces hydrogels sont envisages sous forme de tube mono ou pluri-membranaires pour une utilisation en tant que substituts vasculaires de petit diametre (<6mm). En effet, l'ingenierie vasculaire presente, encore de nos jours, de nombreuses limitations lorsqu'il est question de vaisseaux de petits calibres. Notre demarche consiste en la modulation des parametres structuraux (degre d'acetylation, masse molaire) et environnementaux (concentration du bain de gelification, du collodion) intervenants dans le procede d'elaboration des hydrogels pour atteindre les criteres physiques, biologiques et mecaniques compatibles avec cette application. L'etude morphologique des hydrogels par Cryo-Microscopie Electronique a Balayage (Cryo-MEB), via une methode de preparation originale a permis une meilleure comprehension de l'organisation micro-structurale et multi-echelle des hydrogels de chitosane. Cette approche fondamentale a ete couplee a une evaluation in vivo des proprietes biologiques des hydrogels ainsi qu'a des caracterisations mecaniques des substituts vasculaires. En particulier, l'evaluation de la suturabilite de nos substituts a mene au developpement d'une formulation donnant lieu a des hydrogels physiques de chitosane suturables ayant fait l'objet d'un depot de brevet (N° de depot FR1363099). Le controle et la modulation des parametres d'elaboration des hydrogels ont permis l'obtention de substituts vasculaire cellularisables et respectant les exigences (suture, compliance, resistance a l'eclatement) concernant leur implantation in vivo

Research paper thumbnail of ヒアルロン酸の混合物の脱塩による高分子電解質錯体及びキトサン物理化学的研究と構造解析【Powered by NICT】

Research paper thumbnail of Polyelectrolyte complexes via desalting mixtures of hyaluronic acid and chitosan—Physicochemical study and structural analysis

Carbohydrate Polymers, 2016

Highlights:  The controlled assembly of chitosan and hyaluronic acid was achieved.  Physicochem... more Highlights:  The controlled assembly of chitosan and hyaluronic acid was achieved.  Physicochemical parameters of chitosan and the influence on the PECs were investigated.  Different physical forms as colloidal suspensions and coacervates were obtained.  The nanostructure of the different hyaluronic/ chitosan complexes was investigated.

Research paper thumbnail of Physicochemical modulation of chitosan-based hydrogels induces different biological responses: Interest for tissue engineering

Journal of Biomedical Materials Research Part A, 2013

Polysaccharide-based hydrogels are remarkable materials for the development of tissue engineering... more Polysaccharide-based hydrogels are remarkable materials for the development of tissue engineering strategies as they meet several critical requirements for such applications and they may partly mimic the extracellular matrix. Chitosan is widely envisioned as hydrogel in biomedical fields for its bioresorbability, biocompatibility, and fungistatic and bacteriostatic properties. In this study, we report that the modulation of the polymer concentration, the degree of acetylation, the gelation processes [or neutralization routes (NR)] in the preparation of different chitosan-based hydrogels lead to substantially and significantly different biological responses. We show that it is possible to tune the physicochemical characteristics, mechanical properties, and biological responses of such matrices. Physical hydrogels prepared from highly acetylated chitosan were softer, degraded quickly in vivo, and were not suitable for in vitro culture of human mesenchymal stem and progenitor derived endothelial cells. In contrast, for a same chitosan concentration and obtained by the same processing route, a low degree of acetylation chitosan hydrogel provided a more elastic material, better cell adhesion on its surface and tissue regeneration, and restored tissue neo-vascularization as well. This work offers promising and innovative perspectives for the design of hydrogel materials with tunable properties for tissue engineering and regenerative medicine. V

Research paper thumbnail of Small Diameter Vascular Substitues Based on Physical Chitosan Hydrogels : Proof of Concept

Le chitosane presente des proprietes biologiques (biocompatibilite, bioresorbabilite, bioactivite... more Le chitosane presente des proprietes biologiques (biocompatibilite, bioresorbabilite, bioactivite) idealement adaptees a des applications en ingenierie tissulaire. Dans cette etude partenariale (Programme ANR TECSAN 2010 ChitoArt), nous avons travaille a l'elaboration d'hydrogels physiques de chitosane a proprietes physico-chimiques et biologiques variees et controlees, sans utilisation d'agents de reticulation externes. Ces hydrogels sont envisages sous forme de tube mono ou pluri-membranaires pour une utilisation en tant que substituts vasculaires de petit diametre (<6mm). En effet, l'ingenierie vasculaire presente, encore de nos jours, de nombreuses limitations lorsqu'il est question de vaisseaux de petits calibres. Notre demarche consiste en la modulation des parametres structuraux (degre d'acetylation, masse molaire) et environnementaux (concentration du bain de gelification, du collodion) intervenants dans le procede d'elaboration des hydrogels p...

Research paper thumbnail of Highly stretchable hydrogels from complex coacervation of natural polyelectrolytes

Soft Matter

Polyelectrolyte complexation between chitosan and hyaluronic acid at pH between 2 and 3 leads to ... more Polyelectrolyte complexation between chitosan and hyaluronic acid at pH between 2 and 3 leads to highly stretchable hydrogels.

Research paper thumbnail of In Vitro Mechanical Property Evaluation of Chitosan-Based Hydrogels Intended for Vascular Graft Development

Journal of cardiovascular translational research, Jan 31, 2017

Vascular grafts made of synthetic polymers perform poorly in cardiac and peripheral bypass applic... more Vascular grafts made of synthetic polymers perform poorly in cardiac and peripheral bypass applications. In these applications, chitosan-based materials can be produced and shaped to provide a novel scaffold for vascular tissue engineering. The goal of this study was to evaluate in vitro the mechanical properties of a novel chitosan formulation to assess its potential for this scaffold. Two chitosan-based hydrogel tubes were produced by modulating chitosan concentration. Based on the standard ISO 7198:1998, the hydrogel tubes were characterized in vitro in terms of suture retention strength, tensile strength, compliance, and burst pressure. By increasing chitosan concentration, suture retention value increased to reach 1.1 N; average burst strength and elastic moduli also increased significantly. The compliance seemed to exhibit a low value for chitosan tubes of high concentration. By modulating chitosan concentration, we produced scaffolds with suitable mechanical properties to be ...

Research paper thumbnail of Biosynthetic Multi-hydrogels for tissue engineering

Research paper thumbnail of Bioresorption mechanisms of Chitosan Physical Hydrogels: A Scanning Electron Microscopy Study

Materials Science and Engineering: C, 2014

Tissue-engineered biodegradable medical devices are widely studied and systems must present suita... more Tissue-engineered biodegradable medical devices are widely studied and systems must present suitable balance between versatility and elaboration simplicity. In this work, we aim at illustrating that such equilibrium can be found by processing chitosan physical hydrogels without external cross-linker. Chitosan concentration, degree of acetylation, solvent composition, and neutralization route were modulated in order to obtain hydrogels exhibiting different physico-chemical properties. The resulting in vivo biological response was investigated by Scanning Electron Microscopy. "Soft" hydrogels were obtained from chitosan of high degree of acetylation (35%) and by the neutralization with gaseous ammonia of a chitosan acetate aqueous solutions presenting low polymer concentration (Cp=1.6% w/w). "Harder" hydrogels were obtained from chitosan with lower degree of acetylation (5%) and after neutralization in sodium hydroxide bath (1M) of hydro-alcoholic chitosan solutions (50/50 w/w water/1,2-propanediol) with a polymer concentration of 2.5% w/w. Soft and hard hydrogels exhibited bioresorption times from below 10 days to higher than 60 days, respectively. We also evidenced that cell colonization and neovascularization mechanisms depend on the hydrogel-aggregated structure that is controlled by elaboration conditions and possibly in relation with mechanical properties. Specific processing conditions induced micron-range capillaries formation, which can be assimilated to colonization channels, also acting on the resorption scenario.

Research paper thumbnail of Bioresorption mechanisms of Chitosan Physical Hydrogels: A Scanning Electron Microscopy Study

Materials Science and Engineering: C, 2014

Tissue-engineered biodegradable medical devices are widely studied and systems must present suita... more Tissue-engineered biodegradable medical devices are widely studied and systems must present suitable balance between versatility and elaboration simplicity. In this work, we aim at illustrating that such equilibrium can be found by processing chitosan physical hydrogels without external cross-linker. Chitosan concentration, degree of acetylation, solvent composition, and neutralization route were modulated in order to obtain hydrogels exhibiting different physico-chemical properties. The resulting in vivo biological response was investigated by scanning electron microscopy. &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Soft&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; hydrogels were obtained from chitosan of high degree of acetylation (35%) and by the neutralization with gaseous ammonia of a chitosan acetate aqueous solutions presenting low polymer concentration (Cp=1.6% w/w). &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Harder&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; hydrogels were obtained from chitosan with lower degree of acetylation (5%) and after neutralization in sodium hydroxide bath (1M) of hydro-alcoholic chitosan solutions (50/50 w/w water/1,2-propanediol) with a polymer concentration of 2.5% w/w. Soft and hard hydrogels exhibited bioresorption times from below 10 days to higher than 60 days, respectively. We also evidenced that cell colonization and neo-vascularization mechanisms depend on the hydrogel-aggregated structure that is controlled by elaboration conditions and possibly in relation with mechanical properties. Specific processing conditions induced micron-range capillary formation, which can be assimilated to colonization channels, also acting on the resorption scenario.

Research paper thumbnail of Liposome-loaded chitosan physical hydrogel: Toward a promising delayed-release biosystem

Carbohydrate Polymers, 2015

This work deals with the elaboration of an original biosystem in view of its application as drug ... more This work deals with the elaboration of an original biosystem in view of its application as drug delayed-release device in biomedical area. This innovative &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;hybrid&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; system is composed of phosphatidylcholine liposomes entrapped within a chitosan physical hydrogel (only constituted of polymer and water). To this end, pre-formed liposomes were suspended into chitosan solutions, and the polymer gelation process was subsequently carried out following particular experimental conditions. This liposome incorporation did absolutely not prevent the gel formation as shown by rheological properties of the resulting tridimensional matrix. The presence of liposomes within the hydrogel was confirmed by fluorescence and cryo-scanning electron microscopies. Then, the expected concept of delayed-release of this &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;hybrid&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; system was proved using a model water soluble molecule (carboxyfluorescein, CF) encapsulated in liposomes, themselves incorporated into the chitosan hydrogel. The CF release was assayed after repeated and intensive washings of hydrogels, and was found to be higher in the CF-in-hydrogel systems in comparison with the CF-in-liposomes-in-hydrogel ones, demonstrating a CF delayed-release thanks to lipid vesicles.