References of "Freichels, Hélène"
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See detailα-Acetal, ω-alkyne poly(ethylene oxide) as a versatile building block for the synthesis of glycoconjugated graft-copolymers suited for targeted drug delivery
Freichels, Hélène; Alaimo, David ULg; Auzély-Velty, Rachel et al

in Bioconjugate Chemistry (2012), 23(9), 1740-1752

α-Acetal, ω-alkyne poly(ethylene oxide) was synthesized as building block of glycoconjugated poly(ε-caprolactone)-graft-poly(ethylene oxide) (PCL-g-PEO) copolymers. The alkyne group is indeed instrumental ... [more ▼]

α-Acetal, ω-alkyne poly(ethylene oxide) was synthesized as building block of glycoconjugated poly(ε-caprolactone)-graft-poly(ethylene oxide) (PCL-g-PEO) copolymers. The alkyne group is indeed instrumental for the PEGylation of a poly(α-azido-ε-caprolactone-co-ε-caprolactone) copolymer by the Huisgen’s 1,3 dipolar cycloaddition, i.e., a click reaction. Moreover, deprotection of the acetal end-group of the hydrophilic PEO grafts followed by reductive amination of the accordingly formed aldehyde with an aminated sugar is a valuable strategy of glycoconjugation of the graft copolymer, whose micelles are then potential. A model molecule (fluoresceinamine) was first considered in order to optimize the experimental conditions for the reductive amination. These conditions were then extended to the decoration of the graft copolymer micelles with mannose, which is a targeting agent of dendritic cells and macrophages. The bioavailability of the sugar units at the surface of micelles was investigated by surface plasmon resonance (SPR). The same question was addressed to nanoparticles stabilized by the graft copolymer. Enzyme linked lectin assay (ELLA) confirmed the availability of mannose at the nanoparticle surface. [less ▲]

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See detailClickable PEG conjugate obtained by ‘‘clip’’ photochemistry: Synthesis and
Pourcelle, Vincent; Le Duff, Cécile S.; Freichels, Hélène et al

in Journal of Fluorine Chemistry (2012), 140

In this paper, we describe a grafting methodology associated to a quantitative 19F NMR method (qNMR) for the conjugation of small molecules on a PEG building block aimed at click chemistry applications in ... [more ▼]

In this paper, we describe a grafting methodology associated to a quantitative 19F NMR method (qNMR) for the conjugation of small molecules on a PEG building block aimed at click chemistry applications in the domain of drug delivery systems. Acetylenic PEG (PEG-yne) was first derivatized with a fluorinated benzyl amine (TagF6) by means of photografting of a trifluoromethylphenyl diazirine bifunctional linker (TPD-clip). The amount of TagF6 grafted on PEG-yne was calculated by NMR using an internal standard (trifluoroethanol) and adjusting of the acquisition and processing parameters. NMR is used as a valuable alternative to the complex procedures often employed for the quantification of functionalities on biomaterials. The accuracy of the qNMR methodology was attested by controlling its linearity, the determination of limits of quantification and the percentage of recovery. A good assessment of the TagF6 grafting rates was obtained after taking into account the inherent unspecific adsorption that occurs on materials. This versatile methodology that combines simple chemistry and a common analytical tool was, in a second time, applied to the preparation of a PEG conjugated with a RGD (Arg-Gly-Asp) peptidomimetic in a controlled manner. [less ▲]

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See detailEasy functionalization of amphiphilic poly(ethylene oxide)-b-poly(ε-caprolactone) copolymer micelles with unprotected sugar: synthesis and recognition by lectins
Freichels, Hélène; Auzély-Velty, Rachel; Lecomte, Philippe ULg et al

in Polymer Chemistry (2012), 3(6), 1436-1145

This paper aims at reporting the end-functionalization of a PEO block of an amphiphilic α-acetal-PEO-b-PCL copolymer. The acetal end-group, which is the fragment of the initiator used in the EO ... [more ▼]

This paper aims at reporting the end-functionalization of a PEO block of an amphiphilic α-acetal-PEO-b-PCL copolymer. The acetal end-group, which is the fragment of the initiator used in the EO polymerization, was first hydrolyzed into an aldehyde that was then reacted with an amine by reductive amination reaction in water. This two-step derivatization was carried out in one pot. In a preliminary study a model amine, i.e. fluorescein amine, was used and the impact of the composition, thus of the Hydrophilic–Lipophilic Balance (HLB) of the amphiphilic copolymer, was studied. The experimental conditions were extended to the coupling of an aminated mannose to the diblock copolymer. The frozen micelles formed by the mannosylated copolymer proved to form complexes with various lectins as shown by Surface Plasmon Resonance (SPR) and Isothermal Titration Calorimetry (ITC). [less ▲]

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See detailDevelopment of a biomechanical model of deer antler cancellous bone based on X-ray microtomographic images
de Bien, Charlotte ULg; Mengoni, Marlène ULg; D'Otreppe, Vinciane ULg et al

in Micro-CT User Meeting 2012 - Abstract Book (2012, April)

Finite element models accurately compute the mechanical response of bone and bone-like materials when the models include their detailed microstructure. The aim of this paper is to develop and validate a ... [more ▼]

Finite element models accurately compute the mechanical response of bone and bone-like materials when the models include their detailed microstructure. The aim of this paper is to develop and validate a biomechanical model for deer antler cancellous bone tissue based on X-ray microtomographic images. In order to simulate the mechanical behavior under compressive load using a finite element model, images obtained by X-ray microtomography were exported into Metafor, which is an non-linear finite element software initially developed at University of Liège for metal forming processes. This software has recently found biomedical applications. The ultimate goal is to compare model predictions with the mechanical behavior observed experimentally using the Skyscan material testing stage under compression mode. The creation of the biomechanical model mesh from segmented μCT images, its integration into the software Metafor and the simulation of a compression test are described in this paper. [less ▲]

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See detailSynthesis of poly(lactide-co-glycolide-co-ε-caprolactone)-graft-mannosylated poly(ethylene oxide) copolymers by combination of “clip” and “click” chemistries
Freichels, Hélène; Pourcelle, Vincent; Auzély-Velty, Rachel et al

in Biomacromolecules (2012), 13(3), 760-768

Poly(lactide-co-glycolide) (PLGA) is extensively used in pharmaceutical applications, for example, in targeted drug delivery, because of biocompatibility and degradation rate, which is easily tuned by the ... [more ▼]

Poly(lactide-co-glycolide) (PLGA) is extensively used in pharmaceutical applications, for example, in targeted drug delivery, because of biocompatibility and degradation rate, which is easily tuned by the copolymer composition. Nevertheless, synthesis of sugar-labeled amphiphilic copolymers with a PLGA backbone is quite a challenge because of high sensitivity to hydrolytic degradation. This Article reports on the synthesis of a new amphiphilic copolymer of PLGA grafted by mannosylated poly(ethylene oxide) (PEO). A novel building block, that is, α-methoxy-ω-alkyne PEO-clip-N-hydroxysuccinimide (NHS) ester, was prepared on purpose by photoreaction of a diazirine containing molecular clip. This PEO block was mannosylated by reaction of the NHS ester groups with an aminated sugar, that is, 2-aminoethyl-α-d-mannopyroside. Then, the alkyne ω-end-group of PEO was involved in a copper alkyne- azide coupling (CuAAC) with the pendent azides of the aliphatic copolyester. The targeted mannose-labeled poly(lactide-co-glycolide-co-ε-caprolactone)-graft-poly(ethylene oxide) copolymer was accordingly formed. Copolymerization of d,l-lactide and glycolide with α-chloro-ε-caprolactone, followed by substitution of chlorides by azides provided the azido-functional PLGA backbone. Finally, micelles of the amphiphilic mannosylated graft copolymer were prepared in water, and their interaction with Concanavalin A (ConA), a glyco-receptor protein, was studied by quartz crystal microbalance. This study concluded to the prospect of using this novel bioconjugate in targeted drug delivery. [less ▲]

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See detailA non-linear homogeneous model for bone-like materials under compressive load.
Mengoni, Marlène ULg; Voide, Romain; de Bien, Charlotte ULg et al

in International Journal for Numerical Methods in Biomedical Engineering (2012), 28(2), 334-348

Finite element (FE) models accurately compute the mechanical response of bone and bone-like materials when the models include their detailed microstructure. In order to simulate non-linear behavior, which ... [more ▼]

Finite element (FE) models accurately compute the mechanical response of bone and bone-like materials when the models include their detailed microstructure. In order to simulate non-linear behavior, which currently is only feasible at the expense of extremely high computational costs, coarser models can be used if the local morphology has been linked to the apparent mechanical behavior. The aim of this paper is to implement and validate such a constitutive law. This law is able to capture the non-linear structural behavior of bone-like materials through the use of fabric tensors. It also allows for irreversible strains using an elastoplastic material model incorporating hardening. These features are expressed in a constitutive law based on the anisotropic continuum damage theory coupled with isotropic elastoplasticity in a finite strains framework. This material model was implemented into Metafor, a non-linear FE software. The implementation was validated against experimental data of cylindrical samples subjected to compression. Three materials with bone-like microstructure were tested : aluminum foams of variable density (ERG, Oakland, CA), PLA (polylactic acid) foam (CERM, University of Liège) and cancellous bone tissue of a deer antler (Faculty of Veterinary Medicine, University of Liège). [less ▲]

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See detailSugar-labeled and PEGylated (bio)degradable polymers intended for targeted drug delivery systems
Freichels, Hélène; Jérôme, Robert ULg; Jérôme, Christine ULg

in Carbohydrate Polymers (2011), 86(3), 1093-1106

This paper aims at giving a comprehensive view of the research effort devoted to the preparation of sugar coated long-circulating degradable polymers intended for drug delivery applications. In the recent ... [more ▼]

This paper aims at giving a comprehensive view of the research effort devoted to the preparation of sugar coated long-circulating degradable polymers intended for drug delivery applications. In the recent past, many research projects have focused on the controlled drug delivery and, therefore, on the design of drug carriers. Among them, polymeric carriers have great potential because they can be chemically modified to a large extent and so endowed with specific properties. For instance, depending on the selected polymer, either the circulation time in the bloodstream can be increased very significantly (long-circulating polymer) or the drug carrier can be completely degraded after administration. Moreover, active targeting, i.e., carriers bearing a ligand known for specific affinity for one tissue, has emerged as a method of choice in targeting the delivery of drugs. This concept is of the utmost importance because the large variety of receptors present in the body makes the selective targeting a must in order to prevent any healthy tissue from being damaged irreversibly. The purpose of this paper is to emphasize that carbohydrates are very promising pilot molecules for the next generation of drug delivery [less ▲]

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See detail"Clip" and "click" chemistries combination: toward easy PEGylation of degradable aliphatic polyesters
Freichels, Hélène; Pourcelle, Vincent; Le Duff, Cécile S. et al

in Macromolecular Rapid Communications (2011), 32(7), 616-621

The combination of “clip” and “click” reactions provides a versatile and straightforward pathway for the synthesis of functional amphiphilic and degradable copolymers valuable for biomedical applications ... [more ▼]

The combination of “clip” and “click” reactions provides a versatile and straightforward pathway for the synthesis of functional amphiphilic and degradable copolymers valuable for biomedical applications such as targeted drug-delivery vehicles. [less ▲]

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See detailFluorescent labeling of degradable poly(lactide-co-glycolide) for cellular nanoparticles tracking in living cells
Freichels, Hélène; Danhier, Fabienne; Préat, Véronique et al

in International Journal of Artificial Organs (2011), 34(2), 152-160

Fluorescent-labeled aliphatic polyesters are essential materials for in vitro and in vivo studies of the behavior of these biodegradable polymers in interaction with cells or in a body. In particular, the ... [more ▼]

Fluorescent-labeled aliphatic polyesters are essential materials for in vitro and in vivo studies of the behavior of these biodegradable polymers in interaction with cells or in a body. In particular, the direct cellular localization of drug delivery systems based on these materials allows better understanding of the internalization mechanism and determination of the pharmacokinetics. Polylactide-co-glycolide (PLGA) is a rapidly degradable copolymer widely used in pharmaceutics and nanomedecine. It was prepared by ring-opening polymerization of lactide and glycolide in order to obtain a well-defined material to investigate conditions allowing the covalent linkage of a fluorescent dye (fluorescein) while preserving the macromolecular characteristics of the polymer. The success of the functionalization was ascertained by proton nuclear magnetic resonance (1H NMR), size-exclusion chromatography (SEC) and fluorescence spectroscopy. [less ▲]

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See detailTargeting nanoparticles to M cells with non-peptidic ligands for oral vaccination
Fievez, Virginie; Plapied, Laurence; des Rieux, Anne et al

in European Journal of Pharmaceutics & Biopharmaceutics (2009)

The presence of RGD on nanoparticles allows the targeting of β1 integrins at the apical surface of human M cells and the enhancement of an immune response after oral immunization. To check the hypothesis ... [more ▼]

The presence of RGD on nanoparticles allows the targeting of β1 integrins at the apical surface of human M cells and the enhancement of an immune response after oral immunization. To check the hypothesis that non-peptidic ligands targeting intestinal M cells or APCs would be more efficient for oral immunization than RGD, novel non-peptidic and peptidic analogs (RGD peptidomimitic (RGDp), LDV derivative (LDVd) and LDV peptidomimetic (LDVp)) as well as mannose were grafted on the PEG chain of PCL–PEG and incorporated in PLGA-based nanoparticles. RGD and RGDp significantly increased the transport of nanoparticles across an in vitro model of human M cells as compared to enterocytes. RGD, LDVp, LDVd and mannose enhanced nanoparticle uptake by macrophages in vitro. The intraduodenal immunization with RGDp-, LDVd- or mannose-labeled nanoparticles elicited a higher production of IgG antibodies than the intramuscular injection of free ovalbumin or intraduodenal administration of either non-targeted or RGD-nanoparticles. Targeted formulations were also able to induce a cellular immune response. In conclusion, the in vitro transport of nanoparticles, uptake by macrophages and the immune response were positively influenced by the presence of ligands at the surface of nanoparticles. These targeted-nanoparticles could thus represent a promising delivery system for oral immunization. [less ▲]

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See detailSynthesis of functional amphiphilic copolymers for the elaboration of third generation drug nanocarriers
Alaimo, David ULg; Freichels, Hélène; Jérôme, Robert ULg et al

Poster (2007, March 08)

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