An elastomeric scaffold containing poly(glycerol sebacate) and hydroxypropyl-β-cyclodextrin was d... more An elastomeric scaffold containing poly(glycerol sebacate) and hydroxypropyl-β-cyclodextrin was developed for soft tissue engineering.
Polymer-free electrospinning of tannic acid and subsequent crosslinking with Fe(iii) in water was... more Polymer-free electrospinning of tannic acid and subsequent crosslinking with Fe(iii) in water was demonstrated resulting in hybrid supramolecular nanofibres.
Polyrotaxanes (PRs) based on a-cyclodextrins (a-CDs) threaded onto 22 kg mol À1 poly(ethylene oxi... more Polyrotaxanes (PRs) based on a-cyclodextrins (a-CDs) threaded onto 22 kg mol À1 poly(ethylene oxide) (PEO) chains in concentrated solution in dimethyl sulfoxide (DMSO) showed the particularity to form physical gels when resting at 21 8C. The wide range of studied degrees of complexation N (from 7 up to 176), where N is the number of threaded a-CDs per PEO chain, allowed to better understand the molecular origin of the physical gelation. The non-monotonous evolution of the mechanical properties of the gels with the complexation degree can be attributed to the crystallization of naked PEO segments and the aggregation of a-CDs. In fact, differential scanning calorimetry measurements carried out on these physical gels showed two distinct endothermic peaks. The first peak at 29.4 8C was attributed to the crystals of naked PEO segments (the parts of the PR molecule not covered by a-CDs). The second peak at 32.0 8C was attributed to a-CD aggregates. The dissolution enthalpy of the low temperature peak decreased monotonously with increasing N and the dissolution enthalpy of the high temperature peak increased monotonously with increasing N. These results were confirmed using X-ray scattering and 1 H NMR spectroscopy measurements showing these two contributions to gelation. These results showed that the cohesion of the physical gel was due to the crystallization of naked PEO segments, on the one hand, and, on the other hand, to the regular aggregation of a-CDs driven by intra-and inter-molecular hydrogen bonding interactions of their hydroxyl groups.
Assemblies of nanoparticles are studied in many research fields from physics to medicine. However... more Assemblies of nanoparticles are studied in many research fields from physics to medicine. However, as it is often difficult to produce mono-dispersed particles, investigating the key parameters enhancing their efficiency is blurred by wide size distributions. Indeed, near-field methods analyse a part of the sample that might not be representative of the full size distribution and macroscopic methods give average information including all particle sizes. Here, we introduce temperature differential ferromagnetic nuclear resonance spectra that allow sampling the crystallographic structure, the chemical composition and the chemical order of non-interacting ferromagnetic nanoparticles for specific size ranges within their size distribution. The method is applied to cobalt nanoparticles for catalysis and allows extracting the size effect from the crystallographic structure effect on their catalytic activity. It also allows sampling of the chemical composition and chemical order within the size distribution of alloyed nanoparticles and can thus be useful in many research fields.
ABSTRACT Tissue engineering is a multidisciplinary science that offers a strategy to circumvent t... more ABSTRACT Tissue engineering is a multidisciplinary science that offers a strategy to circumvent the problems related with regenerative and therapeutic procedures. The development of biomaterials made of biodegradable polymers and hydroxyapatite (HA) has been extensively investigated to create biological substitutes to regenerate and repair bone tissue. In this research, a bionanocomposite scaffold based on poly (butylene adipate-co-terephthalate) (PBAT) and HA nanoparticles was prepared by electrospinning and spin coating techniques. The characterization of the composite structures was made by scanning and transmission electron microscopy (SEM and TEM), differential scanning calorimetry (DSC), Fourier Transform infrared (FTIR), wide angle X-rays diffraction (WAXD) and tensile mechanical properties, which were measured by dynamical mechanical analysis (DMA). Afterwards, human adipose stem cells (hASC) were seeded over the composite material and its differentiation in osteoblasts and in vivo biocompatibility were evaluated. This study showed that the composite material had a proper morphology, structure and mechanical properties which ensured the hASC attachment, proliferation and differentiation in bone cells. Finally, as implants, the composite material triggered only a mild inflammatory response.
Herein, it is demonstrated that star pseudopolyrotaxanes (star-pPRs) obtained from the inclusion ... more Herein, it is demonstrated that star pseudopolyrotaxanes (star-pPRs) obtained from the inclusion complexation of α-cyclodextrin (CD) and four-branched star poly(ε-caprolactone) (star-PCL) organize into nanoplatelets in dimethyl sulfoxide at 35 °C. This peculiar property, not observed for linear pseudopolyrotaxanes, allows the processing of star-pPRs while preserving their supramolecular assembly. Thus, original PCL:star-pPR core:shell nanofibers are elaborated by coaxial electrospinning. The star-pPR shell ensures the presence of available CD hydroxyl functions on the fiber surface allowing its postfunctionalization. As proof of concept, fluorescein isothiocyanate is grafted. Moreover, the morphology of the fibers is maintained due to the star-pPR shell that acts as a shield, preventing the fiber dissolution during chemical modification. The proposed strategy is simple and avoids the synthesis of polyrotaxanes, i.e., pPR end-capping to prevent the CD dethreading. As PCL is widely us...
Tissue engineering aims at developing functional substitutes for damaged tissues by mimicking nat... more Tissue engineering aims at developing functional substitutes for damaged tissues by mimicking natural tissues. In particular, tissue engineering for bone regeneration enables healing of some bone diseases. Thus, several methods have been developed in order to produce implantable biomaterial structures that imitate the constitution of bone. Electrospinning is one of these methods. This technique produces nonwoven scaffolds made of nanofibers which size and organization match those of the extracellular matrix. Until now, seldom electrospun scaffolds were produced with thickness exceeding one millimeter. This article introduces a new kind of electrospun membrane called 3D scaffold of thickness easily exceeding one centimeter. The manufacturing involves a solution of poly(ε-caprolactone) in DMF/DCM system. The aim is to establish parameters for electrospinning in order to characterize these 3D scaffolds and, establish whether such scaffolds are potentially interesting for bone regenerat...
An elastomeric scaffold containing poly(glycerol sebacate) and hydroxypropyl-β-cyclodextrin was d... more An elastomeric scaffold containing poly(glycerol sebacate) and hydroxypropyl-β-cyclodextrin was developed for soft tissue engineering.
Polymer-free electrospinning of tannic acid and subsequent crosslinking with Fe(iii) in water was... more Polymer-free electrospinning of tannic acid and subsequent crosslinking with Fe(iii) in water was demonstrated resulting in hybrid supramolecular nanofibres.
Polyrotaxanes (PRs) based on a-cyclodextrins (a-CDs) threaded onto 22 kg mol À1 poly(ethylene oxi... more Polyrotaxanes (PRs) based on a-cyclodextrins (a-CDs) threaded onto 22 kg mol À1 poly(ethylene oxide) (PEO) chains in concentrated solution in dimethyl sulfoxide (DMSO) showed the particularity to form physical gels when resting at 21 8C. The wide range of studied degrees of complexation N (from 7 up to 176), where N is the number of threaded a-CDs per PEO chain, allowed to better understand the molecular origin of the physical gelation. The non-monotonous evolution of the mechanical properties of the gels with the complexation degree can be attributed to the crystallization of naked PEO segments and the aggregation of a-CDs. In fact, differential scanning calorimetry measurements carried out on these physical gels showed two distinct endothermic peaks. The first peak at 29.4 8C was attributed to the crystals of naked PEO segments (the parts of the PR molecule not covered by a-CDs). The second peak at 32.0 8C was attributed to a-CD aggregates. The dissolution enthalpy of the low temperature peak decreased monotonously with increasing N and the dissolution enthalpy of the high temperature peak increased monotonously with increasing N. These results were confirmed using X-ray scattering and 1 H NMR spectroscopy measurements showing these two contributions to gelation. These results showed that the cohesion of the physical gel was due to the crystallization of naked PEO segments, on the one hand, and, on the other hand, to the regular aggregation of a-CDs driven by intra-and inter-molecular hydrogen bonding interactions of their hydroxyl groups.
Assemblies of nanoparticles are studied in many research fields from physics to medicine. However... more Assemblies of nanoparticles are studied in many research fields from physics to medicine. However, as it is often difficult to produce mono-dispersed particles, investigating the key parameters enhancing their efficiency is blurred by wide size distributions. Indeed, near-field methods analyse a part of the sample that might not be representative of the full size distribution and macroscopic methods give average information including all particle sizes. Here, we introduce temperature differential ferromagnetic nuclear resonance spectra that allow sampling the crystallographic structure, the chemical composition and the chemical order of non-interacting ferromagnetic nanoparticles for specific size ranges within their size distribution. The method is applied to cobalt nanoparticles for catalysis and allows extracting the size effect from the crystallographic structure effect on their catalytic activity. It also allows sampling of the chemical composition and chemical order within the size distribution of alloyed nanoparticles and can thus be useful in many research fields.
ABSTRACT Tissue engineering is a multidisciplinary science that offers a strategy to circumvent t... more ABSTRACT Tissue engineering is a multidisciplinary science that offers a strategy to circumvent the problems related with regenerative and therapeutic procedures. The development of biomaterials made of biodegradable polymers and hydroxyapatite (HA) has been extensively investigated to create biological substitutes to regenerate and repair bone tissue. In this research, a bionanocomposite scaffold based on poly (butylene adipate-co-terephthalate) (PBAT) and HA nanoparticles was prepared by electrospinning and spin coating techniques. The characterization of the composite structures was made by scanning and transmission electron microscopy (SEM and TEM), differential scanning calorimetry (DSC), Fourier Transform infrared (FTIR), wide angle X-rays diffraction (WAXD) and tensile mechanical properties, which were measured by dynamical mechanical analysis (DMA). Afterwards, human adipose stem cells (hASC) were seeded over the composite material and its differentiation in osteoblasts and in vivo biocompatibility were evaluated. This study showed that the composite material had a proper morphology, structure and mechanical properties which ensured the hASC attachment, proliferation and differentiation in bone cells. Finally, as implants, the composite material triggered only a mild inflammatory response.
Herein, it is demonstrated that star pseudopolyrotaxanes (star-pPRs) obtained from the inclusion ... more Herein, it is demonstrated that star pseudopolyrotaxanes (star-pPRs) obtained from the inclusion complexation of α-cyclodextrin (CD) and four-branched star poly(ε-caprolactone) (star-PCL) organize into nanoplatelets in dimethyl sulfoxide at 35 °C. This peculiar property, not observed for linear pseudopolyrotaxanes, allows the processing of star-pPRs while preserving their supramolecular assembly. Thus, original PCL:star-pPR core:shell nanofibers are elaborated by coaxial electrospinning. The star-pPR shell ensures the presence of available CD hydroxyl functions on the fiber surface allowing its postfunctionalization. As proof of concept, fluorescein isothiocyanate is grafted. Moreover, the morphology of the fibers is maintained due to the star-pPR shell that acts as a shield, preventing the fiber dissolution during chemical modification. The proposed strategy is simple and avoids the synthesis of polyrotaxanes, i.e., pPR end-capping to prevent the CD dethreading. As PCL is widely us...
Tissue engineering aims at developing functional substitutes for damaged tissues by mimicking nat... more Tissue engineering aims at developing functional substitutes for damaged tissues by mimicking natural tissues. In particular, tissue engineering for bone regeneration enables healing of some bone diseases. Thus, several methods have been developed in order to produce implantable biomaterial structures that imitate the constitution of bone. Electrospinning is one of these methods. This technique produces nonwoven scaffolds made of nanofibers which size and organization match those of the extracellular matrix. Until now, seldom electrospun scaffolds were produced with thickness exceeding one millimeter. This article introduces a new kind of electrospun membrane called 3D scaffold of thickness easily exceeding one centimeter. The manufacturing involves a solution of poly(ε-caprolactone) in DMF/DCM system. The aim is to establish parameters for electrospinning in order to characterize these 3D scaffolds and, establish whether such scaffolds are potentially interesting for bone regenerat...
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Papers by Guy Schlatter