References of "Piel, Géraldine"
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See detailCHARACTERIZATION AND OPTIMIZATION OF PEPTIDE ENCAPSULATION IN PEGYLATED LIPOSOMES
Ducat, Emilie ULg; Brion, Michael; Evrard, Brigitte ULg et al

Poster (2009)

Purpose: The purpose of this work is to study the peptide encapsulation into PEGylated liposomes. Two formulations (SPC:CHOL:mPEG-750-DSPE (47:47:6) or SPC:CHOL:mPEG-2000-DSPE (47:47:6)) were investigated ... [more ▼]

Purpose: The purpose of this work is to study the peptide encapsulation into PEGylated liposomes. Two formulations (SPC:CHOL:mPEG-750-DSPE (47:47:6) or SPC:CHOL:mPEG-2000-DSPE (47:47:6)) were investigated. Methods: Blank SUV liposomes were prepared by the lipid film hydration and the encapsulation was achieved by applying freeze-thawing cycles. Because many factors may influence peptide entrapment (number of freeze-thawing cycles (NC), lipid concentration (LC), peptide concentration (PC), mixing time (MT) and liposome composition (COMP)), a design of experiment (DOE) was performed. Results: The screening permitted to identify two factors having a positive and significant influence on the encapsulation efficiencies (NC and LC) while the liposome composition had a relatively weak effect. For the second part of the DOE, the positive factors were optimized for liposomes containing mPEG2000. The obtained results revealed a theoretical optimum at 64.75±3.55% when 11 cycles were applied and for the following LC: 36.1mM SPC, 36.1mM CHOL and 4mM mPEG-2000-DSPE. Experimental results showed an encapsulation efficiency of 62.68±2.93%. Conclusion: The DOE led to significant improvement of encapsulation for liposomes containing mPEG2000. Thereafter, an optimization design for liposomes containing mPEG750 will be started. Acknowledgements: This work was supported by the Ministry of the Walloon Region. [less ▲]

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See detailFORMULATION OF PEPTIDE-LOADED LIPOSOMES FOR INTRAVENOUS DELIVERY: OPTIMIZATION OF THE ENCAPSULATION EFFICIENCY
Ducat, Emilie ULg; Brion, Michael; Evrard, Brigitte ULg et al

Conference (2009)

Purpose: Print 3G is a peptidic antagonist of oncoprotein involved in breast cancer, containing 25 amino acids. The purpose of this work is to study the peptide encapsulation into PEGylated liposomes ... [more ▼]

Purpose: Print 3G is a peptidic antagonist of oncoprotein involved in breast cancer, containing 25 amino acids. The purpose of this work is to study the peptide encapsulation into PEGylated liposomes composed of SPC:CHOL:mPEG-2000-DSPE (47:47:6). Methods: Loaded unilamellar vesicles were prepared by hydration of lipid film method. Unfortunately, a loss of Print 3G was observed during the different steps of this manufacturing technique giving rise to encapsulation efficiencies (EE) close to 0 %. Thus, the freeze-thawing method was used to enhance the amount of Print 3G encapsulated into blank liposomes prepared using the above procedure. Because many factors may influence the peptide entrapment into the vesicles (number of freeze-thawing cycles (NC), lipid concentration (LC), peptide concentration (PC) and mixing time (MT)), a design of experiment (DOE) was performed (for the screening, a Plackett and Burman plan; for the optimization, a central composite design). EE were calculated in terms of quantity of peptide loaded in liposomes as a function of quantity operated (EEp) or quantity of lipids (EEl). Results: The EE obtained by the freeze-thawing method in standard conditions (Katanasaka, Ida et al., 2008; Maeda, Bharate et al., 2008), amounted to 26.20 ± 7.98 %, n=3 (EEp) and to 0.26 ± 0.074 % (EEl). Among the different considered parameters, the screening permitted to identify two factors having a positive and significant influence on the EE: NC and LC. Concerning the PC and MT, no influence was revealed. For the second part of the DOE, the positive factors were optimized and obtained results revealed a theoretical optimum at 64.75 ± 3.55 % when 11 freeze-thawing cycles were applied (NC) and for the following LC: 36.1 mM SPC, 36.1 mM CHOL and 4mM mPEG-2000-DSPE. The experimental results showed an encapsulation efficiency of 62.68 ± 2.93 %. Photon correlation spectroscopy and freeze-fracture electron microscopy were also realized to examine the liposome integrity, before and after the freeze-thawing cycles. Conclusion: Changing the manufacturing technique permitted a significant encapsulation of Print 3G into liposomes. The DOE led to a significant improvement of encapsulation efficiencies. References: (1) Katanasaka,Y., Ida,T., Asai,T., Maeda,N., Oku,N., 2008. Effective delivery of an angiogenesis inhibitor by neovessel-targeted liposomes. International Journal of Pharmaceutics, 360, 219-224. (2) Maeda,H., Bharate,G.Y., Daruwalla,J., 2008. Polymeric drugs for efficient tumor-targeted drug delivery based on EPR effect. Eur. J Pharm Biopharm. Acknowledgements: This work was supported by the Ministry of the Walloon Region. [less ▲]

Detailed reference viewed: 77 (2 ULg)
Peer Reviewed
See detailCHARACTERIZATION AND OPTIMIZATION OF PEPTIDE ENCAPSULATION IN PEGYLATED LIPOSOMES
Ducat, Emilie ULg; Brion, Michael; Evrard, Brigitte ULg et al

Poster (2009)

Purpose: Print 3G is a peptidic antagonist of oncoprotein involved in breast cancer, containing 25 amino acids. The purpose of this work is to study the peptide encapsulation into PEGylated liposomes. Two ... [more ▼]

Purpose: Print 3G is a peptidic antagonist of oncoprotein involved in breast cancer, containing 25 amino acids. The purpose of this work is to study the peptide encapsulation into PEGylated liposomes. Two formulations composed of SPC:CHOL:mPEG-750-DSPE (47:47:6) or SPC:CHOL:mPEG-2000-DSPE (47:47:6) were investigated. Methods: Unilamellar vesicles containing either mPEG750 or mPEG2000 were prepared by hydration of lipid films method. Unfortunately, a loss of Print 3G was observed during the different steps of this manufacturing technique giving rise to encapsulation efficiencies close to 0 %. Thus, the freeze-thawing method was used to enhance the amount of Print 3G encapsulated into blank liposomes prepared using the above procedure. Because many factors may influence the peptide entrapment into the vesicles (number of freeze-thawing cycles, lipid concentration, peptide concentration, mixing time and liposome composition), a design of experiment was performed (for the screening, a Plackett and Burman plan; for the optimization, a central composite design). Results: The encapsulation efficiencies obtained by the freeze-thawing method in standard conditions, varied between 17.26 ± 0.46 % (n=3) for liposomes containing mPEG750 and 26.20 ± 7.98 % (n=3) for those comprising mPEG2000. Among the different considered factors, the screening permitted to identify two factors having a positive and significant influence on the encapsulation efficiencies: the number of freeze-thawing cycles and the lipid concentration, while the presence of mPEG2000 or mPEG750 had a relatively weak effect on the encapsulation. Concerning the peptide concentration and the mixing time, no influence was revealed. For the second part of the DOE, the positive factors were optimized for the liposomes containing mPEG2000. The obtained results for liposomes containing mPEG2000 revealed a theoretical optimum at 64.75 ± 3.55 % when 11 freeze-thawing cycles were applied and for the following lipid concentrations: 36.1 mM SPC, 36.1 mM CHOL and 4mM mPEG-2000-DSPE. The experimental results showed an encapsulation efficiency of 62.68 ± 2.93 %. Conclusion: Changing the manufacturing technique permitted a significant encapsulation of Print 3G into liposomes. The DOE led to a significant improvement of encapsulation efficiencies for the liposomes containing mPEG2000. Thereafter, an optimization design for liposomes containing mPEG750 will be started. Acknowledgements: This work was supported by the Ministry of the Walloon Region. [less ▲]

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See detailCARACTERISATION ET OPTIMISATION DE L’ENCAPSULATION D’UN PEPTIDE ANTAGONISTE D’ONCOPROTEINE AU SEIN DE LIPOSOMES PEGYLES
Ducat, Emilie ULg; Brion, Michael; Evrard, Brigitte ULg et al

Scientific conference (2009)

Introduction : Print 3G est un peptide antagoniste d’une oncoprotéine impliquée dans le cancer du sein, composé de 25 acides aminés. Le but de ce travail est d’étudier l’encapsulation de ce peptide au ... [more ▼]

Introduction : Print 3G est un peptide antagoniste d’une oncoprotéine impliquée dans le cancer du sein, composé de 25 acides aminés. Le but de ce travail est d’étudier l’encapsulation de ce peptide au sein de liposomes pegylés. Deux types de formulations de liposomes ont été étudiés, le premier contenant des mPEG750-DSPE et le second des mPEG2000-DSPE. Méthode : Des liposomes unilamellaires composés de SPC:CHOL:mPEG750-DSPE ou de SPC:CHOL:mPEG2000-DSPE (47:47:6) encapsulant le peptide ont été préparés par la technique d’évaporation du film. L’observation d’une adsorption conséquente de Print 3G sur les instruments utilisés a conduit à l’utilisation de la méthode de fabrication par cycles gel-dégel. Etant donné que plusieurs facteurs peuvent influencer l’encapsulation du peptide à l’intérieur des liposomes, une planification expérimentale a été engagée (pour le screening, un plan de Plackett et Burman et pour l’optimisation, un plan composite faces centrées). Résultats : Par la technique des cycles gel-dégel généralement décrite dans la littérature(1; 2), les taux d’encapsulation obtenus étaient de 17,26 ± 0,46 % (n=3) pour les liposomes contenant des mPEG750 et de 26,20 ± 7,98 % (n=3) pour ceux contenant des mPEG2000. Le plan de screening a permis de dégager deux facteurs ayant une influence positive sur l’encapsulation : la concentration en lipides et le nombre de cycles gel-dégel. Ceux-ci ont été optimisés pour chaque type de mPEG. Les résultats obtenus pour les mPEG2000 mettent en évidence un optimum théorique de 64,75% pour un nombre de cycles égal à 11 et pour une concentration en lipides SPC:CHOL:mPEG2000-DSPE de 36.1mM:36.1mM:4mM. Les résultats expérimentaux ont permis d’obtenir un taux d’encapsulation de 62,68 ± 2,93 %. Conclusion et perspectives : Le changement de technique de fabrication a permis l’encapsulation significative du peptide à l’intérieur des liposomes. La planification expérimentale a ensuite conduit à l’amélioration significative des taux d’encapsulation pour les liposomes contenant des mPEG2000. Par la suite, un plan d’optimisation pour les liposomes contenant des mPEG750 sera mis en œuvre. Remerciements: Ces recherches ont été réalisées avec le soutien de la Région Wallonne. Références: 1. Y.Katanasaka, T.Ida, T.Asai, N.Maeda, and N.Oku. Effective delivery of an angiogenesis inhibitor by neovessel-targeted liposomes. International Journal of Pharmaceutics, 360 (1-2):219-224 (2008). 2. G.A.Ramaldes, J.-R.Deverre, J.-M.Grognet, F.Puisieux, and E.Fattal. Use of an enzyme immunoassay for the evaluation of entrapment efficiency and in vitro stability in intestinal fluids of liposomal bovine serum albumin. International Journal of Pharmaceutics, 143 (1):1-11 (1996). [less ▲]

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Peer Reviewed
See detailTheoretical and Experimental Vibrational Study of Miconazole and Its Dimers with Organic Acids: Application to the IR Characterization of Its Inclusion Complexes with Cyclodextrins
Barillaro, Valéry; Dive, Georges ULg; Ziemons, Eric ULg et al

in International Journal of Pharmaceutics (2008), 350(1-2), 155-165

The geometry, frequency and intensity of the vibrational bands of miconazole were derived from the density functional theory (DFT) calculations with the hybrid functional B3LYP and the 6-31G(d) basis set ... [more ▼]

The geometry, frequency and intensity of the vibrational bands of miconazole were derived from the density functional theory (DFT) calculations with the hybrid functional B3LYP and the 6-31G(d) basis set. Starting from the fully AM1 optimized geometries of miconazole/betaCD/acids complexes, the miconazole/acid dimers were reoptimized at the B3LYP/6-31G(d) level. Three acids were studied: maleic, fumaric and l-tartaric acids. To begin with the vibrational spectral data obtained from solid phase in mid FT-IR spectrum of miconazole and its dimers are assigned based on the results of the normal modes calculations. All the observed spectra and the calculated ones are found to be in good agreement. In a second step, theoretical results allowed the assignment of FT-IR spectrum for the miconazole/HPgammaCD inclusion complex produced by supercritical carbon dioxide treatment and confirmed the inclusion of miconazole. The experimental spectra for the miconazole/HPgammaCD/acids complexes prepared by supercritical carbon dioxide processing were also assigned using theoretical results. The results confirmed the presence of a genuine inclusion complex and also the interaction between miconazole and the acid. [less ▲]

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See detailTheoretical and Experimental Investigations of Organic Acids/Cyclodextrin Complexes and Their Consequences Upon the Formation of Miconazole/Cyclodextrin/Acid Ternary Inclusion Complexes
Barillaro, Valéry; Dive, Georges ULg; Bertholet, Pascal et al

in International Journal of Pharmaceutics (2008), 347(1-2), 62-70

(1)H NMR spectrometry, FT-IR spectroscopy, as well as molecular modeling at the AM1 level and normal mode analysis were used to characterise the interactions and the formation of inclusion complexes ... [more ▼]

(1)H NMR spectrometry, FT-IR spectroscopy, as well as molecular modeling at the AM1 level and normal mode analysis were used to characterise the interactions and the formation of inclusion complexes between three organic acids: maleic, fumaric, L-tartaric acids and betaCD. In aqueous medium, the complexation was confirmed by (1)H NMR spectroscopy using two-dimensional technique. The stable geometries of the complexes were determined by molecular modeling. Experimental infrared frequencies were assigned on the base of the vibrational normal mode calculation at the fully optimized geometry for the inclusion complexes. All the results point out the presence of stable inclusion complexes between acids and betaCD at the solid state. These results show the double role of the acid. Correlated with the theoretical and experimental data previously obtained for the miconazole/CD/acids complexes, in function of both acids and CDs structures, the acids can either stabilize the complexes by formation of a multicomponent complex or form acid/CD inclusion complexes, hindering the guest inclusion. [less ▲]

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See detailSTUDY OF PEGYLATED LIPOSOMES CRYOPROTECTION IN TERMS OF RETENTION EFFICIENCY
Ducat, Emilie ULg; Evrard, Brigitte ULg; Piel, Géraldine ULg

Poster (2008)

Purpose: Print 3G, a peptidic antagonist of oncoproteins involved in breast cancer, was encapsulated in PEGylated liposomes. Seeing its temperature instability, this peptide must be stored at – 20°C. In ... [more ▼]

Purpose: Print 3G, a peptidic antagonist of oncoproteins involved in breast cancer, was encapsulated in PEGylated liposomes. Seeing its temperature instability, this peptide must be stored at – 20°C. In this study, the cryoprotection of PEGylated liposomes was investigated to ensure their stability in terms of size and retention capacity when frozen. Calcein, a self-quenching fluorescent marker encapsulated in liposomes, was used as a tracer of liposome integrity. The release of calcein was studied before and after freezing, with or without cryoprotectants at several concentrations. Methods: Unilamellar vesicles made of SPC:CHOL:mPEG-750-DSPE (47:47:6) or SPC:CHOL:mPEG-2000-DSPE (47:47:6) were prepared by the film evaporation method. Size of the liposomes dispersions containing a cryoprotectant (sucrose, trehalose or lysine) at various concentrations were measured by photon correlation spectroscopy before and after freezing. From these results, two cryoprotectants (at the best molar ratio of sugar-to-lipid) were chosen for future experiments with calcein. Its release from the inner cavity of liposomes was measured fluorometrically before and after freezing, with or without cryoprotectant. The percentage of calcein retained was determined at excitation and emission wavelengths of 490 and 520 nm, respectively. The liposomes were prepared with cryoprotectant either only outside the vesicles or both inside and outside. Results: In regards to the results obtained with PCS, sucrose and trehalose (molar ratio of sugar-to-lipid = 4) were selected for calcein experiments. The best results in terms of retention efficiency were obtained using cryoprotectant inside and outside the vesicles. Liposomes containing mPEG-750-DSPE show the best retention efficiency after freezing with trehalose (75.42 ± 2.39 %, n=3) in comparison with sucrose (62.16 ± 4.34 %, n=3). Liposomes containing mPEG-2000-DSPE doesn’t show significant difference (T-Test) between trehalose (84.27 ± 5.05%, n=3) and sucrose (83.38 ± 3.18 %, n=3). In the future experiments, these results will be compared with experiments of frozen liposomes encapsulating Print 3G. Acknowledgements: This work was supported by the Ministry of the Walloon Region. [less ▲]

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See detailDEVELOPMENT OF AN INTRAPERITONEAL IMPLANT FOR THE ENDOMETRIOSIS TREATMENT
Krier, Fabrice ULg; Nizet, Dominique; Riva, Raphaël ULg et al

Poster (2008)

Detailed reference viewed: 34 (11 ULg)