References of "Préat, Véronique"
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See detailReversibly core-cross-linked micelles sensitive to reductive environment for the design of drug delivery systems
Cajot, Sébastien ULg; Danhier, F.; Collodoro, M. et al

Poster (2011, June 16)

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See detailNovel drug delivery sytem of siRNA based on chitosan, pegylated chitosan and polyethyleneimine
Ragelle, Héloïse; Vandermeulen, Gaëlle; Riva, Raphaël ULg et al

in Human Gene Therapy (2011, June 06), 22

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See detailSynthesis and characterization of reversibly core cross-linked micelles sensitive to reductive environment
Cajot, Sébastien ULg; Danhier, F.; Collodoro, M. et al

Poster (2011, May 12)

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See detailNovel amphiphilic copolymers and design of smart nanoparticles for drug delivery systems
Cajot, Sébastien ULg; Danhier, F.; Lautram, N. et al

Poster (2011, April 29)

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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 detailChitosan and chitosan derivatives in drug delivery and tissue engineering
Riva, Raphaël ULg; Raguelle, Héloïse; des Rieux, Anne et al

in Jayakumar, Rangasamy; Prabaharan, M.; Muzzarelli, Ricardo A. A. (Eds.) Chitosan for Biomaterials II (2011)

Chitosan is a nontoxic, biodegradable, and biocompatible polysaccharide of β(1-4)-linked d-glucosamine and N-acetyl-d-glucosamine. This derivative of natural chitin presents remarkable properties that ... [more ▼]

Chitosan is a nontoxic, biodegradable, and biocompatible polysaccharide of β(1-4)-linked d-glucosamine and N-acetyl-d-glucosamine. This derivative of natural chitin presents remarkable properties that have paved the way for the introduction of chitosan in the biomedical and pharmaceutical fields. Nevertheless, the properties of chitosan, such as its poor solubility in water or in organic solvents, can limit its utilization for a specific application. An elegant way to improve or to impart new properties to chitosan is the chemical modification of the chain, generally by grafting of functional groups, without modification of the initial skeleton in order to conserve the original properties. The functionalization is carried out on the primary amine group, generally by quaternization, or on the hydroxyl group. This review aims to provide an overview of chitosan and chitosan derivatives used for drug delivery, with a special emphasis on chemical modifications of chitosan to achieve specific biomedical purpose. The synthesis of the main chitosan derivatives will be reviewed. The applications of chitosan and these chitosan derivatives will be illustrated. [less ▲]

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See detailSynthesis of core cross-linked micelles for the development of new drug delivery systems
Cajot, Sébastien ULg; Danhier, F.; Lautram, N. et al

Poster (2010, October 29)

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See detailIn vitro identification of targeting ligands of human M cells by phage display
Fievez, V.; Plapied, L.; Plaideau, C. et al

in International Journal of Pharmaceutics (2010), 394(1-2), 35-42

To improve transport of vaccine-loaded nanoparticles, the phage display technology was used to identify novel lead peptides targeting human M cells. Using an in vitro model of the human follicle ... [more ▼]

To improve transport of vaccine-loaded nanoparticles, the phage display technology was used to identify novel lead peptides targeting human M cells. Using an in vitro model of the human follicle-associated epithelium (FAE) which contains both Caco-2 and M cells, a T7 phage display library was screened for its ability either to bind the apical cell surface of or to undergo transcytosis across Caco-2 cells or FAE. The selection for transcytosis across both enterocytes and FAE identified three different peptide sequences (CTGKSC, PAVLG and LRVG) with high frequency. CTGKSC and LRVG sequences enhanced phage transport across M-like cells. When polymeric nanoparticles were grafted with the sequences CTGKSC and LRVG, their transport by FAE was significantly enhanced. These peptides could therefore be used to enhance the transport of vaccine-loaded nanoparticles across the intestinal mucosal barrier. [less ▲]

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See detailTargeting nanoparticles to M cells with non-peptidic ligands for oral vaccination
Freichels, Hélène ULg; Fievez, Virginie; Plapied, Laurence et al

Poster (2010, March 18)

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See detailAcylated and unacylatedghrelin binding to membranes and to ghrelin receptor: Towards a better understanding of the underlying mechanisms
Staes, Edith; Absil, Pierre-Antoine; Lins, Laurence ULg et al

in Biochimica et Biophysica Acta - Biomembranes (2010), 1798

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See detailValidation of a method for the quantitation of ghrelin and unacylated ghrelin by HPLC.
Rozet, Eric ULg; Staes, Edith; Ucakar, Bernard et al

in Journal of Pharmaceutical & Biomedical Analysis (2010), 51(3), 633-9

An HPLC/UV method was first optimized for the separation and quantitation of human acylated and unacylated (or des-acyl) ghrelin from aqueous solutions. This method was validated by an original approach ... [more ▼]

An HPLC/UV method was first optimized for the separation and quantitation of human acylated and unacylated (or des-acyl) ghrelin from aqueous solutions. This method was validated by an original approach using accuracy profiles based on tolerance intervals for the total error measurement. The concentration range that achieved adequate accuracy extended from 1.85 to 59.30microM and 1.93 to 61.60microM for acylated and unacylated ghrelin, respectively. Then, optimal temperature, pH and buffer for sample storage were determined. Unacylated ghrelin was found to be stable in all conditions tested. At 37 degrees C acylated ghrelin was stable at pH 4 but unstable at pH 7.4, the main degradation product was unacylated ghrelin. Finally, this validated HPLC/UV method was used to evaluate the binding of acylated and unacylated ghrelin to liposomes. [less ▲]

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See detailTargeting of tumor endothelium by RGD-grafted PLGA-nanoparticles loaded with Paclitaxel
Danhier, Fabienne; Vroman, Benoît; Lecouturier, Nathalie et al

in Journal of Controlled Release (2009), 140(2), 166-173

Paclitaxel (PTX)-loaded PEGylated PLGA-based nanoparticles (NP) have been previously described as more effective in vitro and in vivo than Taxol®. The aim of this study was to test the hypothesis that our ... [more ▼]

Paclitaxel (PTX)-loaded PEGylated PLGA-based nanoparticles (NP) have been previously described as more effective in vitro and in vivo than Taxol®. The aim of this study was to test the hypothesis that our PEGylated PLGA-based nanoparticles grafted with the RGD peptide or RGD-peptidomimetic (RGDp) would target the tumor endothelium and would further enhance the anti-tumor efficacy of PTX. The ligands were grafted on the PEG chain of PCL-b-PEG included in the nanoparticles. We observed in vitro that RGD-grafted nanoparticles were more associated to Human Umbilical Vein Endothelial cells (HUVEC) by binding to αvβ3 integrin than non-targeted nanoparticles. Doxorubicin was also used to confirm the findings observed for PTX. In vivo, we demonstrated the targeting of RGD and RGDp-grafted nanoparticles to tumor vessels as well as the effective retardation of TLT tumor growth and prolonged survival times of mice treated by PTX-loaded RGD-nanoparticles when compared to non-targeted nanoparticles. Hence, the targeting of anti-cancer drug to tumor endothelium by RGD-labeled NP is a promising approach. [less ▲]

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See detailPaclitaxel-loaded PEGylated PLGA-based nanoparticles: in vitro and in vivo evaluation
Danhier, Fabienne; Lecouturier, Nathalie; Vroman, Benoît et al

in Journal of Controlled Release (2009), 133(1), 11-17

The incorporation efficiency of PTX was higher with the nanoprecipitation technique. The release behavior of PTX exhibited a biphasic pattern characterized by an initial burst release followed by a slower ... [more ▼]

The incorporation efficiency of PTX was higher with the nanoprecipitation technique. The release behavior of PTX exhibited a biphasic pattern characterized by an initial burst release followed by a slower and continuous release. The in vitro anti-tumoral activity was assessed using the Human Cervix Carcinoma cells (HeLa) by the MTT test and was compared to the commercial formulation Taxol® and to Cremophor® EL. When exposed to 25 µg/ml of PTX, the cell viability was lower for PTX-loaded nanoparticles than for Taxol® (IC50 5.5 vs 15.5 µg/ml). Flow cytometry studies showed that the cellular uptake of PTX-loaded nanoparticles was concentration and time dependent. Exposure of HeLa cells to Taxol® and PTX-loaded nanoparticles induced the same percentage of apoptotic cells. PTX-loaded nanoparticles showed greater tumor growth inhibition effect in vivo on TLT tumor, compared with Taxol®. Therefore, PTX-loaded nanoparticles may be considered as an effective anticancer drug delivery system for cancer chemotherapy. [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 detailFunctional amphiphilic and degradable copolymers for drug delivery systems
Freichels, Hélène ULg; Pourcelle, Vincent; Plapied, Laurence et al

Poster (2008, December 18)

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See detailPaclitaxel-loaded PEGylated nanocarriers: Preparation, physicochemical characterization and in vitro anti-tumoral activity
Danhier, F.; Lecouturier, N.; Vroman, Benoit et al

in Acta Clinica Belgica (2008, February 16), 63(2), 124

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See detailPEGylated quaternized copolymer/DNA complexes for gene delivery
Vroman, Benoît; Ferreira, Isabel; Jérôme, Christine ULg et al

in International Journal of Pharmaceutics (2007), 344(1-2), 88-95

The aim of this study was to improve the colloidal stability, decrease unspecific interactions with cells and blood components of a novel gene delivery system composed of epsilon-caprolactone and ... [more ▼]

The aim of this study was to improve the colloidal stability, decrease unspecific interactions with cells and blood components of a novel gene delivery system composed of epsilon-caprolactone and quaternized epsilon-caprolactone. For this purpose, diblock 50/50 copolymer was used to generate complexes-with DNA by either the solvent evaporation technique and by dialysis. The size, surface charge and degree of interaction of the plasmid-loaded formulations were measured. Then, polyplexes were combined with a poly(CL)-b-PEG copolymer to create a hydrophilic corona on the surface of the complexes. The cytotoxicity, transfection efficiency and cellular uptake of polyplexes and their association with PEG were evaluated on HeLa cells. The dialysis method did not allow to reduce the size of complexes as compared to the solvent evaporation method. The zeta potential of polyplexes became positive from a charge ratio of 4. The degree of interaction of copolymer with plasmid DNA was very high. Cytotoxicity and transfection efficiency were found to be comparable to polyethylenimine 50 kDa. Association of polyplexes with poly(CL)-b-PEG copolymer led to a small increase in particle size and a sharp decrease of charge surface. Cytotoxicity, transfection efficiency and cellular uptake were significantly reduced relative to unshielded copolymer/DNA complexes. The PEGylated formulations may be an attractive approach for an in vivo application. [less ▲]

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See detailPEGylated PLGA-based nanoparticles targeting M cells for oral vaccination
Garinot, Marie; Fievez, Virginie; Pourcelle, Vincent et al

in Journal of Controlled Release (2007), 120(3), 195-204

To improve the efficiency of orally delivered vaccines, PEGylated PLGA-based nanoparticles displaying RGD molecules at their surface were designed to target human M cells. RGD grafting was performed by an ... [more ▼]

To improve the efficiency of orally delivered vaccines, PEGylated PLGA-based nanoparticles displaying RGD molecules at their surface were designed to target human M cells. RGD grafting was performed by an original method called "photografting" which covalently linked RGD peptides mainly on the PEG moiety of the PCL-PEG, included in the formulation. First, three non-targeted formulations with size and zeta potential adapted to M cell uptake and stable in gastro-intestinal fluids, were developed. Their transport by an in vitro model of the human Follicle associated epithelium (co-cultures) was largely increased as compared to mono-cultures (Caco-2 cells). RGD-labelling of nanoparticles significantly increased their transport by co-cultures. due to interactions between the RGD ligand and the I intregrins detected at the apical surface of co-cultures. In vivo studies demonstrated that RGD-labelled nanoparticles particularly concentrated in M cells. Finally, ovalbumin-loaded nanoparticles were orally administrated to mice and induced an IgG response, attesting antigen ability to elicit an immune response after oral delivery. [less ▲]

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See detailMonitoring of urea and potassium by reverse iontophoresis in vitro
Wascotte, Valentine; Delgado-Charro, Begona; Rozet, Eric ULg et al

in Pharmaceutical Research (2007), 24(6), 1131-1137

Purpose. Reverse iontophoresis is an alternative to blood sampling for the monitoring of endogenous molecules. Here, the potential of the technique to measure urea and potassium levels non-invasively, and ... [more ▼]

Purpose. Reverse iontophoresis is an alternative to blood sampling for the monitoring of endogenous molecules. Here, the potential of the technique to measure urea and potassium levels non-invasively, and to track their concentrations during hemodialysis, has been examined. Materials and Methods. In vitro experiments were performed to test (a) a series of subdermal urea and potassium concentrations typical of the pathophysiologic range, and (b) a decreasing profile of urea and potassium subdermal concentrations to mimic those which are observed during hemodialysis. Results. (a) After 60-120 min of iontophoresis, linear relationships (p < 0.05) were established between both urea and potassium fluxes and their respective subdermal concentrations. The determination coefficients were above 0.9 after 1 h of current passage using sodium as an internal standard. (b) Reverse iontophoretic fluxes of urea and K+ closely paralleled the decay of the respective concentrations in the subdermal compartment, as would occur during a hemodialysis session. Conclusions. These in vitro experiments demonstrate that urea and potassium can be quantitatively and proportionately extracted by reverse iontophoresis, even when the subdermal concentrations of the analytes are varying with time. These results suggest the non-invasive monitoring of urea and potassium to diagnose renal failure and during hemodialysis is feasible, and that in vivo measurements are warranted. [less ▲]

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See detailImprovement of the decision efficiency of the accuracy profile by means of a desirability function for analytical methods validation - Application to a diacetyl-monoxime colorimetric assay used for the determination of urea in transdermal iontophoretic extracts
Rozet, Eric ULg; Wascotte, Valentine; Lecouturier, Nathalie et al

in Analytica Chimica Acta (2007), 591(2), 239-247

Validation of analytical methods is a widely used and regulated step for each analytical method. However, the classical approaches to demonstrate the ability to quantify of a method do not necessarily ... [more ▼]

Validation of analytical methods is a widely used and regulated step for each analytical method. However, the classical approaches to demonstrate the ability to quantify of a method do not necessarily fulfill this objective. For this reason an innovative methodology was recently introduced by using the tolerance interval and accuracy profile, which guarantee that a pre-defined proportion of future measurements obtained with the method will be included within the acceptance limits. Accuracy profile is an effective decision tool to assess the validity of analytical methods. The methodology to build such a profile is detailed here. However, as for any visual tool it has a part of subjectivity. It was then necessary to make the decision process objective in order to quantify the degree of adequacy of an accuracy profile and to allow a thorough comparison between such profiles. To achieve this, we developed a global desirability index based on the three most important validation criteria: the trueness, the precision and the range. The global index allows the classification of the different accuracy profiles obtained according to their respective response functions. A diacetyl-monoxime colorimetric assay for the determination of urea in transdermal iontophoretic extracts was used to illustrate these improvements. [less ▲]

Detailed reference viewed: 79 (9 ULg)