begu sylvie | Ecole Nationale Superieure de Chimie de Montpellier (ENSCM) (original) (raw)

Papers by begu sylvie

Crystals, 2016

Despite the extensive range of investigations on boronic acids (R-B(OH) 2), some aspects of their... more Despite the extensive range of investigations on boronic acids (R-B(OH) 2), some aspects of their reactivity still need to be explored. This is the case for the coordination chemistry of boronate anions (R-B(OH) 3´) , which has only recently been started to be studied. The purpose of this review is to summarize some of the key features of boronate ligands (and of their cyclic derivatives, benzoxaborolates) in materials: (i) coordination properties; (ii) spectroscopic signatures; and (iii) emerging applications.

New J. Chem., 2003

A non-steroidal anti-inflammatory drug (ibuprofen) has been anchored inside the mesoporous channe... more A non-steroidal anti-inflammatory drug (ibuprofen) has been anchored inside the mesoporous channels of MCM-41-type silica and on a silica gel surface. The relevant anchoring procedure through an ester function has been investigated. It uses the epoxide ring opening of 3-...

Journal of the American Chemical Society, 2011

Drug delivery is one of the major challenges in nanomedicine. 1 Various approaches, including amo... more Drug delivery is one of the major challenges in nanomedicine. 1 Various approaches, including amorphous mesoporous materials, 2 liposomes, 3,4 and polyelectrolytes structures 5 have been proposed for the diffusion and transport of bioactive cargo at predefinite targets in the cell. Recently, Brinker et al. introduced the "proto-cell" concept, corresponding to lipid bilayers onto porous silica nanoparticles (supported lipid bilayers, or SLB). 6 Loading and sealing of the active cargo was achieved through the fusion of liposomes on the silica nanoparticles, leading to an efficient biocompatible vehicle. Moreover, subsequent PEGylation 7 of the nanocomposites can extend the circulation time and targeting of the cells. Successive steps of lipid exchange between silica-supported bilayers and free liposomes can further reduce the bilayer defects, allowing for improved control of the nanovehicles. 8 Liposomes in themselves have been extensively studied as potential drug delivery systems (either with hydrophilic or lipophilic drugs), as they offer an in vivo protection from degradative enzymes, enhanced circulation time, and bioavailability. However, such structures suffer physical instability leading to destabilization processes. 4 In order to protect the fragile structure of liposomes, various strategies were recently proposed in the literature, including: silica layers ("liposil" for liposome and silica), 9À12 silica nanoparticles ("SNCL" for Silica Nanoparticle Coated Liposomes), 4 layers of biocompatible polyelectrolytes ("layersome"), 5 selfassembled organicÀinorganic shells with responsive molecular gates, 13 polycationic brushes. 14 Moreover, Li et al. 15 proposed to use the liposomes as protective capsules for active synthesis of silica solÀgel biocomposites. On one hand, several studies have focused on the so-called liposils where the study of the stability of loaded entities analyzed ABSTRACT: In the context of nanomedicine, liposils (liposomes and silica) have a strong potential for drug storage and release schemes: such materials combine the intrinsic properties of liposome (encapsulation) and silica (increased rigidity, protective coating, pH degradability). In this work, an original approach combining solid state NMR, molecular dynamics, first principles geometry optimization, and NMR parameters calculation allows the building of a precise representation of the organic/inorganic interface in liposils. { 1 HÀ 29 Si} 1 H and { 1 HÀ 31 P} 1 H Double Cross-Polarization (CP) MAS NMR experiments were implemented in order to explore the proton chemical environments around the silica and the phospholipids, respectively. Using VASP (Vienna Ab Initio Simulation Package), DFT calculations including molecular dynamics, and geometry optimization lead to the determination of energetically favorable configurations of a DPPC (dipalmitoylphosphatidylcholine) headgroup adsorbed onto a hydroxylated silica surface that corresponds to a realistic model of an amorphous silica slab. These data combined with first principles NMR parameters calculations by GIPAW (Gauge Included Projected Augmented Wave) show that the phosphate moieties are not directly interacting with silanols. The stabilization of the interface is achieved through the presence of water molecules located in-between the head groups of the phospholipids and the silica surface forming an interfacial H-bonded water layer. A detailed study of the 31 P chemical shift anisotropy (CSA) parameters allows us to interpret the local dynamics of DPPC in liposils. Finally, the VASP/solid state NMR/ GIPAW combined approach can be extended to a large variety of organicÀinorganic hybrid interfaces.

Advances in Composite Materials for Medicine and Nanotechnology, 2011

Materials, 2020

A novel bio-hybrid drug delivery system was obtained involving a Mg/Al-NO3 layered double hydroxi... more A novel bio-hybrid drug delivery system was obtained involving a Mg/Al-NO3 layered double hydroxide (LDH) intercalated either with ibuprofenate anions (IBU) or a phospholipid bilayer (BL) containing a neutral drug, i.e., 17β-estradiol, and then embedded in chitosan beads. The combination of these components in a hierarchical structure led to synergistic effects investigated through characterization of the intermediates and the final bio-composites by XRD, TG, SEM, and TEM. That allowed determining the presence and yield of IBU and of BL in the interlayer space of LDH, and of the encapsulated LDH in the beads, as well as the morphology of the latter. Peculiar attention has been paid to the intercalation process of the BL for which all available data substantiate the hypothesis of a first interaction at the defect of the LDH, as well as on the interaction mode of these components. 1H, 31P and 27Al MAS-NMR studies allowed establishing that the intercalated BL is not homogeneous and lik...

European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V, Jan 18, 2015

Dendritic cells (DCs) are professional antigen-presenting cells that play a critical role in main... more Dendritic cells (DCs) are professional antigen-presenting cells that play a critical role in maintaining the balance between immunity and tolerance and, as such are a promising immunotherapy tool to induce immunity or to restore tolerance. The main challenge to harness the tolerogenic properties of DCs is to preserve their immature phenotype. We recently developed polyion complex micelles, formulated with double hydrophilic block copolymers of poly(methacrylic acid) and poly(ethylene oxide) blocks and able to entrap therapeutic molecules, which did not induce DC maturation. In the current study, the intrinsic destabilizing membrane properties of the polymers were used to optimize endosomal escape property of the micelles in order to propose various strategies to restore tolerance. On the first hand, we showed that high molecular weight (Mw) copolymer-based micelles were efficient to favor the release of the micelle-entrapped peptide into the endosomes, and thus to improve peptide pr...

Lasers in Surgery and Medicine, 1999

The aim of the study was to evaluate the feasibility of retinal thermal damage assessment in a ra... more The aim of the study was to evaluate the feasibility of retinal thermal damage assessment in a rabbit eye model by using laser-induced release of liposome-encapsulated dye. After anesthesia, thermosensitive liposomes (DiStearoyl Phosphatidyl Choline: DSPC) loaded with 5,6-carboxyfluorescein were injected intravenously to pigmented rabbits. Retinal photocoagulations were performed with a 810nm diode laser (P=100-400 mW, laser spot=500 microm, 1s) (OcuLight, IRIS Medical Instruments, Mountain View, CA). Fluorescence measurements in the area of the laser exposures were then realized with a digitized angiograph (CF-60UVi, Canon-Europe, The Netherlands; OcuLab, Life Science Resources, UK). Fluorescent spots were observed for power ranging from 100 +/- 5 mW to 400 +/- 5 mW. The fluorescence intensity increased linearly with the power and reached a plateau at 280 +/- 5 mW. The fluorescence intensity was correlated to the maximum temperature at the center of the laser spot with a linear increase from 42 +/- 3 degrees C to 65 +/- 3 degrees C. These results are in agreement with our two previous studies with DSPC liposomes for temperature measurements in a tissue model and then in a vascular model. This preliminary study demonstrates the possibility of a laser-induced release of liposome-encapsulated dye for a quantification of diode laser induced thermal damage in ophthalmology. Such a method could be useful for a real-time monitoring of laser photocoagulation for conditions such as choroidal neovascular membranes when a precise thermal damage is required near the foveolar area.

Luminescence, 2001

This study aimed to observe liposome uptake by leukocytes in vivo. The study was performed on ski... more This study aimed to observe liposome uptake by leukocytes in vivo. The study was performed on skin by using a dorsal skin-fold chamber implanted in golden hamsters using intravital microscopy. 5 and 6-CF-encapsulated polyethylene glycolated liposomes were injected intravenously. The skin microcirculation was observed with an intravital Eclipse E800 Nikon microscope (using ×40, ×80 magnification) fitted with a Xenon light source and an epifluorescence assembly (excitation, 470 nm, FWHM 40 nm; emission, 540 nm, FWHM 40 nm). An ultra-high sensitivity videocamera mounted on the microscope projected the image onto a monitor, and the images (720 × 576 pixels) were recorded for playback analysis with a digital video cassette recorder. An acute inflammatory response was obtained by removing one complete layer of skin and the underlying fascia and avascular tissue on the opposing side of the flap corresponding to an area equivalent to the window aperture. Using this model and set-up, leukocyte rolling and adhesion were easily observed and the entry of PEGylated liposomes into hamster blood leukocytes was studied for a period of 6 h. PEGylated liposomes were clearly identified alone inside the blood flow and inside the leukocytes as soon as the inflammatory reaction appeared. This study shows for the first time that blood leukocytes in their natural milieu of whole blood are capable of interacting with, and taking up, liposomes. This observation is in accordance with previous in vitro studies. Copyright © 2001 John Wiley & Sons, Ltd.

Biomaterials, 2009

Double-hydrophilic block copolymer micelles were designed as vectors for ex vivo dendritic cell e... more Double-hydrophilic block copolymer micelles were designed as vectors for ex vivo dendritic cell engineering to improve the delivery of therapeutic molecules in such immune cells. Polymethacrylic acid-b-polyethylene oxide (PMAA 2100 -b-POE 5000 )/poly-L-lysine micelles were optimised and showed a hydrodynamic diameter of 30 nm with a peculiar core organised with hydrogen bonds as well as hydrophobic domains. The micelles proved high stability in physiological conditions (pH and ionic strength) and were also able to disassemble under acidic conditions mimicking acidic endolysosomes. The efficient endocytosis of the optimised micelles tested on bone marrow-derived dendritic cells was monitored by fluorescence-activated cell sorting and microscopy analysis. Finally, the micelle biocompatibility permitted a complete control of the dendritic cell-maturation process widening the therapeutical potential of such engineered dendritic cells for cancer vaccines as well as for immunomodulation in autoimmune diseases.

Chemistry of Materials, 2009

... Anne Aubert-Pou ssel, Ramona Polexe, Eliska Leitmanova, Dan A. Lerner, Jean-Marie Devoisselle... more ... Anne Aubert-Pou ssel, Ramona Polexe, Eliska Leitmanova, Dan A. Lerner, Jean-Marie Devoisselle and Didier Tichit. ... Obviously, this must be a complex multistep process that may begin with the adsorption of the liposome by its external lipid layer to the rim of the mineral LDH. ...

Langmuir, 2007

Liposomes prepared from a mixture of L-R-dipalmitoylphosphatidylcholine and the PEGilated phospho... more Liposomes prepared from a mixture of L-R-dipalmitoylphosphatidylcholine and the PEGilated phospholipid N-(carbonylmethoxypoly(ethylene glycol 2000))-1,2-distearoyl-sn-glycero-3-phosphoethanolamine were used as templates for the production of silica and alkylated silica ∼100 nm capsules, "liposils", entrapping aqueous solutions of anionic dyes. Triggered release of this content was successfully affected by either low-frequency ultrasound or by microwave treatments. Cryo-TEM was used to follow the formation process of these particles, which are aggregated in a chain-like manner. A mechanism explaining this phenomenon is suggested.

Journal of Controlled Release, 2011

For many years, a great deal of interest has been focusing on the optimization of peptide present... more For many years, a great deal of interest has been focusing on the optimization of peptide presentation by dendritic cells (DCs) using peptide-encapsulated particles, in order to enhance the immune response. Nowadays, DCs are also known to be involved in peripheral tolerance, inducing anergy or regulatory T lymphocytes. To preserve the plasticity of DCs, we formulated non-cytotoxic pH-sensitive polyion complex micelles based on an original tripartite association of polymethacrylic acid-b-polyethylene oxide, poly-Llysine and fluorescent-peptide: OVAFITC peptide, as a model drug. We demonstrated that the OVAFITC peptide was successfully entrapped into the micelles, released into DC endosomes thanks to the pHsensitivity property of the micelles, and efficiently loaded onto MHC class II molecules. The phenotype as well as the cytokinic secretion profile of the mature and immature DCs loaded with peptide-encapsulated micelles was unaltered by the tripartite polyion micelles. The efficient loading of the peptide by immature and mature DCs was shown by the in vitro proliferation of OVA-specific transgenic T cells. Therefore, the present results show that the tripartite polyion complex micelles can be used as efficient peptide vectors immunogically inert for ex vivo DCs engineering without modifying their intrinsic immune plasticity.

Journal of Biomedical Optics, 2007

Our purpose is to evaluate intramucosal gastric pH video imaging by 2Ј ,7Ј-bis͑carboxyethyl͒-5,6-... more Our purpose is to evaluate intramucosal gastric pH video imaging by 2Ј ,7Ј-bis͑carboxyethyl͒-5,6-carboxyfluorescein ͑BCECF͒ fluorescence ratio techniques. We use a video endoscopic imaging system and BCECF as the pH fluorescent probe. Systemic in vivo pH variations are studied in 10 pigs: five in the control group and five with respiratory acidosis induced through rebreathing. The intramucosal pH of the gastric wall is measured every 5 s and the results demonstrate a good correlation ͑pearson correlation= 0.832͒ between blood gases pH measurements and pH measured with the video endocopic imaging system. Our results confirm the feasibility of using BCECF fluorescence pH imaging to measure intramucosal pH in vivo.

Microvascular Research, 1998

This study reinvestigates the spectral properties of ICG amphiphilic properties of ICG are consis... more This study reinvestigates the spectral properties of ICG amphiphilic properties of ICG are consistent with fixation of some ICG molecules on sites other than plasmatic (Indocyanine green) in vivo, the role of quenching, and the possibility of an interaction of ICG with blood com-proteins after injection. The process of fixation of ICG molecules on surface components or within the vascular ponents and/or vessel walls. ICG quenching as a function of concentration was studied by spectrophotometry on endothelium could be due to a change in the microenvironment of some ICG molecules. ᭧ 1998 Academic Press whole blood samples from golden hamsters. Fluorescence ICG characteristics were evaluated by front-face Key Words: indocyanine green; fluorescence; proteins; blood; quenching. fluorometry. In vivo, fluorescence measurements were performed on the femoral artery of golden hamsters. In vitro, on whole blood samples, fluorescence intensity is

Carbohydrate Polymers, 2004

The polyelectrolyte complex formation between iota- (ι-)carrageenan and poly(l-lysine) (PLL) has ... more The polyelectrolyte complex formation between iota- (ι-)carrageenan and poly(l-lysine) (PLL) has been investigated in HEPES 5 mM, NaCl 150 mM pH 6.5 at 25 °C, in dilute conditions. After building of the ternary phase diagram of the system, the formation of soluble polyelectrolyte complexes in transparent systems has been evidenced by means of spectroscopic techniques. Absorption spectrum of methylene blue (MB+) interacting with ι-carrageenan chains, in presence of increasing amounts of the polypeptide, as well as fluorescence polarization of a FITC-labeled PLL and circular dichroism spectrum of PLL, in presence of increasing amounts of the polysaccharide, have been studied. In all cases, the endpoint occurred for a peptide to polysaccharide weight ratio of about 0.82, indicating an approximate 1/1 charge stoichiometry of the polyelectrolyte complex formed. Furthermore, the polyelectrolyte complex formation process was proved to be conformation-directing as PLL adopts a right-handed α-helical conformation when mixed with ι-carrageenan.

European Journal of Pharmaceutics and Biopharmaceutics, 2004

The aim of this study is to determine the feasibility of loading biologically active molecules in... more The aim of this study is to determine the feasibility of loading biologically active molecules into templated mesoporous silica (MCM 41). This material shows an important mesoporosity associated to hexagonally organized channels, a narrow pore size distribution and a large surface area. Ibuprofen was selected as a model molecule since it is a well documented and much used anti-inflammatory drug. Furthermore, it has a lipophilic character and its molecular size is suitable for inclusion within the mesopores of the MCM 41 material.

Lasers in Surgery and Medicine, 1997

Background and Objectives: The present study was undertaken to evaluate the feasibility of therma... more Background and Objectives: The present study was undertaken to evaluate the feasibility of thermal damage assessment of blood vessels by using laser-induced release of liposome-encapsulated dye. Study Design/Materials and Methods: Experiments were per-formed in a hamster ...

Crystals, 2016

Despite the extensive range of investigations on boronic acids (R-B(OH) 2), some aspects of their... more Despite the extensive range of investigations on boronic acids (R-B(OH) 2), some aspects of their reactivity still need to be explored. This is the case for the coordination chemistry of boronate anions (R-B(OH) 3´) , which has only recently been started to be studied. The purpose of this review is to summarize some of the key features of boronate ligands (and of their cyclic derivatives, benzoxaborolates) in materials: (i) coordination properties; (ii) spectroscopic signatures; and (iii) emerging applications.

New J. Chem., 2003

A non-steroidal anti-inflammatory drug (ibuprofen) has been anchored inside the mesoporous channe... more A non-steroidal anti-inflammatory drug (ibuprofen) has been anchored inside the mesoporous channels of MCM-41-type silica and on a silica gel surface. The relevant anchoring procedure through an ester function has been investigated. It uses the epoxide ring opening of 3-...

Journal of the American Chemical Society, 2011

Drug delivery is one of the major challenges in nanomedicine. 1 Various approaches, including amo... more Drug delivery is one of the major challenges in nanomedicine. 1 Various approaches, including amorphous mesoporous materials, 2 liposomes, 3,4 and polyelectrolytes structures 5 have been proposed for the diffusion and transport of bioactive cargo at predefinite targets in the cell. Recently, Brinker et al. introduced the "proto-cell" concept, corresponding to lipid bilayers onto porous silica nanoparticles (supported lipid bilayers, or SLB). 6 Loading and sealing of the active cargo was achieved through the fusion of liposomes on the silica nanoparticles, leading to an efficient biocompatible vehicle. Moreover, subsequent PEGylation 7 of the nanocomposites can extend the circulation time and targeting of the cells. Successive steps of lipid exchange between silica-supported bilayers and free liposomes can further reduce the bilayer defects, allowing for improved control of the nanovehicles. 8 Liposomes in themselves have been extensively studied as potential drug delivery systems (either with hydrophilic or lipophilic drugs), as they offer an in vivo protection from degradative enzymes, enhanced circulation time, and bioavailability. However, such structures suffer physical instability leading to destabilization processes. 4 In order to protect the fragile structure of liposomes, various strategies were recently proposed in the literature, including: silica layers ("liposil" for liposome and silica), 9À12 silica nanoparticles ("SNCL" for Silica Nanoparticle Coated Liposomes), 4 layers of biocompatible polyelectrolytes ("layersome"), 5 selfassembled organicÀinorganic shells with responsive molecular gates, 13 polycationic brushes. 14 Moreover, Li et al. 15 proposed to use the liposomes as protective capsules for active synthesis of silica solÀgel biocomposites. On one hand, several studies have focused on the so-called liposils where the study of the stability of loaded entities analyzed ABSTRACT: In the context of nanomedicine, liposils (liposomes and silica) have a strong potential for drug storage and release schemes: such materials combine the intrinsic properties of liposome (encapsulation) and silica (increased rigidity, protective coating, pH degradability). In this work, an original approach combining solid state NMR, molecular dynamics, first principles geometry optimization, and NMR parameters calculation allows the building of a precise representation of the organic/inorganic interface in liposils. { 1 HÀ 29 Si} 1 H and { 1 HÀ 31 P} 1 H Double Cross-Polarization (CP) MAS NMR experiments were implemented in order to explore the proton chemical environments around the silica and the phospholipids, respectively. Using VASP (Vienna Ab Initio Simulation Package), DFT calculations including molecular dynamics, and geometry optimization lead to the determination of energetically favorable configurations of a DPPC (dipalmitoylphosphatidylcholine) headgroup adsorbed onto a hydroxylated silica surface that corresponds to a realistic model of an amorphous silica slab. These data combined with first principles NMR parameters calculations by GIPAW (Gauge Included Projected Augmented Wave) show that the phosphate moieties are not directly interacting with silanols. The stabilization of the interface is achieved through the presence of water molecules located in-between the head groups of the phospholipids and the silica surface forming an interfacial H-bonded water layer. A detailed study of the 31 P chemical shift anisotropy (CSA) parameters allows us to interpret the local dynamics of DPPC in liposils. Finally, the VASP/solid state NMR/ GIPAW combined approach can be extended to a large variety of organicÀinorganic hybrid interfaces.

Advances in Composite Materials for Medicine and Nanotechnology, 2011

Materials, 2020

A novel bio-hybrid drug delivery system was obtained involving a Mg/Al-NO3 layered double hydroxi... more A novel bio-hybrid drug delivery system was obtained involving a Mg/Al-NO3 layered double hydroxide (LDH) intercalated either with ibuprofenate anions (IBU) or a phospholipid bilayer (BL) containing a neutral drug, i.e., 17β-estradiol, and then embedded in chitosan beads. The combination of these components in a hierarchical structure led to synergistic effects investigated through characterization of the intermediates and the final bio-composites by XRD, TG, SEM, and TEM. That allowed determining the presence and yield of IBU and of BL in the interlayer space of LDH, and of the encapsulated LDH in the beads, as well as the morphology of the latter. Peculiar attention has been paid to the intercalation process of the BL for which all available data substantiate the hypothesis of a first interaction at the defect of the LDH, as well as on the interaction mode of these components. 1H, 31P and 27Al MAS-NMR studies allowed establishing that the intercalated BL is not homogeneous and lik...

European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V, Jan 18, 2015

Dendritic cells (DCs) are professional antigen-presenting cells that play a critical role in main... more Dendritic cells (DCs) are professional antigen-presenting cells that play a critical role in maintaining the balance between immunity and tolerance and, as such are a promising immunotherapy tool to induce immunity or to restore tolerance. The main challenge to harness the tolerogenic properties of DCs is to preserve their immature phenotype. We recently developed polyion complex micelles, formulated with double hydrophilic block copolymers of poly(methacrylic acid) and poly(ethylene oxide) blocks and able to entrap therapeutic molecules, which did not induce DC maturation. In the current study, the intrinsic destabilizing membrane properties of the polymers were used to optimize endosomal escape property of the micelles in order to propose various strategies to restore tolerance. On the first hand, we showed that high molecular weight (Mw) copolymer-based micelles were efficient to favor the release of the micelle-entrapped peptide into the endosomes, and thus to improve peptide pr...

Lasers in Surgery and Medicine, 1999

The aim of the study was to evaluate the feasibility of retinal thermal damage assessment in a ra... more The aim of the study was to evaluate the feasibility of retinal thermal damage assessment in a rabbit eye model by using laser-induced release of liposome-encapsulated dye. After anesthesia, thermosensitive liposomes (DiStearoyl Phosphatidyl Choline: DSPC) loaded with 5,6-carboxyfluorescein were injected intravenously to pigmented rabbits. Retinal photocoagulations were performed with a 810nm diode laser (P=100-400 mW, laser spot=500 microm, 1s) (OcuLight, IRIS Medical Instruments, Mountain View, CA). Fluorescence measurements in the area of the laser exposures were then realized with a digitized angiograph (CF-60UVi, Canon-Europe, The Netherlands; OcuLab, Life Science Resources, UK). Fluorescent spots were observed for power ranging from 100 +/- 5 mW to 400 +/- 5 mW. The fluorescence intensity increased linearly with the power and reached a plateau at 280 +/- 5 mW. The fluorescence intensity was correlated to the maximum temperature at the center of the laser spot with a linear increase from 42 +/- 3 degrees C to 65 +/- 3 degrees C. These results are in agreement with our two previous studies with DSPC liposomes for temperature measurements in a tissue model and then in a vascular model. This preliminary study demonstrates the possibility of a laser-induced release of liposome-encapsulated dye for a quantification of diode laser induced thermal damage in ophthalmology. Such a method could be useful for a real-time monitoring of laser photocoagulation for conditions such as choroidal neovascular membranes when a precise thermal damage is required near the foveolar area.

Luminescence, 2001

This study aimed to observe liposome uptake by leukocytes in vivo. The study was performed on ski... more This study aimed to observe liposome uptake by leukocytes in vivo. The study was performed on skin by using a dorsal skin-fold chamber implanted in golden hamsters using intravital microscopy. 5 and 6-CF-encapsulated polyethylene glycolated liposomes were injected intravenously. The skin microcirculation was observed with an intravital Eclipse E800 Nikon microscope (using ×40, ×80 magnification) fitted with a Xenon light source and an epifluorescence assembly (excitation, 470 nm, FWHM 40 nm; emission, 540 nm, FWHM 40 nm). An ultra-high sensitivity videocamera mounted on the microscope projected the image onto a monitor, and the images (720 × 576 pixels) were recorded for playback analysis with a digital video cassette recorder. An acute inflammatory response was obtained by removing one complete layer of skin and the underlying fascia and avascular tissue on the opposing side of the flap corresponding to an area equivalent to the window aperture. Using this model and set-up, leukocyte rolling and adhesion were easily observed and the entry of PEGylated liposomes into hamster blood leukocytes was studied for a period of 6 h. PEGylated liposomes were clearly identified alone inside the blood flow and inside the leukocytes as soon as the inflammatory reaction appeared. This study shows for the first time that blood leukocytes in their natural milieu of whole blood are capable of interacting with, and taking up, liposomes. This observation is in accordance with previous in vitro studies. Copyright © 2001 John Wiley & Sons, Ltd.

Biomaterials, 2009

Double-hydrophilic block copolymer micelles were designed as vectors for ex vivo dendritic cell e... more Double-hydrophilic block copolymer micelles were designed as vectors for ex vivo dendritic cell engineering to improve the delivery of therapeutic molecules in such immune cells. Polymethacrylic acid-b-polyethylene oxide (PMAA 2100 -b-POE 5000 )/poly-L-lysine micelles were optimised and showed a hydrodynamic diameter of 30 nm with a peculiar core organised with hydrogen bonds as well as hydrophobic domains. The micelles proved high stability in physiological conditions (pH and ionic strength) and were also able to disassemble under acidic conditions mimicking acidic endolysosomes. The efficient endocytosis of the optimised micelles tested on bone marrow-derived dendritic cells was monitored by fluorescence-activated cell sorting and microscopy analysis. Finally, the micelle biocompatibility permitted a complete control of the dendritic cell-maturation process widening the therapeutical potential of such engineered dendritic cells for cancer vaccines as well as for immunomodulation in autoimmune diseases.

Chemistry of Materials, 2009

... Anne Aubert-Pou ssel, Ramona Polexe, Eliska Leitmanova, Dan A. Lerner, Jean-Marie Devoisselle... more ... Anne Aubert-Pou ssel, Ramona Polexe, Eliska Leitmanova, Dan A. Lerner, Jean-Marie Devoisselle and Didier Tichit. ... Obviously, this must be a complex multistep process that may begin with the adsorption of the liposome by its external lipid layer to the rim of the mineral LDH. ...

Langmuir, 2007

Liposomes prepared from a mixture of L-R-dipalmitoylphosphatidylcholine and the PEGilated phospho... more Liposomes prepared from a mixture of L-R-dipalmitoylphosphatidylcholine and the PEGilated phospholipid N-(carbonylmethoxypoly(ethylene glycol 2000))-1,2-distearoyl-sn-glycero-3-phosphoethanolamine were used as templates for the production of silica and alkylated silica ∼100 nm capsules, "liposils", entrapping aqueous solutions of anionic dyes. Triggered release of this content was successfully affected by either low-frequency ultrasound or by microwave treatments. Cryo-TEM was used to follow the formation process of these particles, which are aggregated in a chain-like manner. A mechanism explaining this phenomenon is suggested.

Journal of Controlled Release, 2011

For many years, a great deal of interest has been focusing on the optimization of peptide present... more For many years, a great deal of interest has been focusing on the optimization of peptide presentation by dendritic cells (DCs) using peptide-encapsulated particles, in order to enhance the immune response. Nowadays, DCs are also known to be involved in peripheral tolerance, inducing anergy or regulatory T lymphocytes. To preserve the plasticity of DCs, we formulated non-cytotoxic pH-sensitive polyion complex micelles based on an original tripartite association of polymethacrylic acid-b-polyethylene oxide, poly-Llysine and fluorescent-peptide: OVAFITC peptide, as a model drug. We demonstrated that the OVAFITC peptide was successfully entrapped into the micelles, released into DC endosomes thanks to the pHsensitivity property of the micelles, and efficiently loaded onto MHC class II molecules. The phenotype as well as the cytokinic secretion profile of the mature and immature DCs loaded with peptide-encapsulated micelles was unaltered by the tripartite polyion micelles. The efficient loading of the peptide by immature and mature DCs was shown by the in vitro proliferation of OVA-specific transgenic T cells. Therefore, the present results show that the tripartite polyion complex micelles can be used as efficient peptide vectors immunogically inert for ex vivo DCs engineering without modifying their intrinsic immune plasticity.

Journal of Biomedical Optics, 2007

Our purpose is to evaluate intramucosal gastric pH video imaging by 2Ј ,7Ј-bis͑carboxyethyl͒-5,6-... more Our purpose is to evaluate intramucosal gastric pH video imaging by 2Ј ,7Ј-bis͑carboxyethyl͒-5,6-carboxyfluorescein ͑BCECF͒ fluorescence ratio techniques. We use a video endoscopic imaging system and BCECF as the pH fluorescent probe. Systemic in vivo pH variations are studied in 10 pigs: five in the control group and five with respiratory acidosis induced through rebreathing. The intramucosal pH of the gastric wall is measured every 5 s and the results demonstrate a good correlation ͑pearson correlation= 0.832͒ between blood gases pH measurements and pH measured with the video endocopic imaging system. Our results confirm the feasibility of using BCECF fluorescence pH imaging to measure intramucosal pH in vivo.

Microvascular Research, 1998

This study reinvestigates the spectral properties of ICG amphiphilic properties of ICG are consis... more This study reinvestigates the spectral properties of ICG amphiphilic properties of ICG are consistent with fixation of some ICG molecules on sites other than plasmatic (Indocyanine green) in vivo, the role of quenching, and the possibility of an interaction of ICG with blood com-proteins after injection. The process of fixation of ICG molecules on surface components or within the vascular ponents and/or vessel walls. ICG quenching as a function of concentration was studied by spectrophotometry on endothelium could be due to a change in the microenvironment of some ICG molecules. ᭧ 1998 Academic Press whole blood samples from golden hamsters. Fluorescence ICG characteristics were evaluated by front-face Key Words: indocyanine green; fluorescence; proteins; blood; quenching. fluorometry. In vivo, fluorescence measurements were performed on the femoral artery of golden hamsters. In vitro, on whole blood samples, fluorescence intensity is

Carbohydrate Polymers, 2004

The polyelectrolyte complex formation between iota- (ι-)carrageenan and poly(l-lysine) (PLL) has ... more The polyelectrolyte complex formation between iota- (ι-)carrageenan and poly(l-lysine) (PLL) has been investigated in HEPES 5 mM, NaCl 150 mM pH 6.5 at 25 °C, in dilute conditions. After building of the ternary phase diagram of the system, the formation of soluble polyelectrolyte complexes in transparent systems has been evidenced by means of spectroscopic techniques. Absorption spectrum of methylene blue (MB+) interacting with ι-carrageenan chains, in presence of increasing amounts of the polypeptide, as well as fluorescence polarization of a FITC-labeled PLL and circular dichroism spectrum of PLL, in presence of increasing amounts of the polysaccharide, have been studied. In all cases, the endpoint occurred for a peptide to polysaccharide weight ratio of about 0.82, indicating an approximate 1/1 charge stoichiometry of the polyelectrolyte complex formed. Furthermore, the polyelectrolyte complex formation process was proved to be conformation-directing as PLL adopts a right-handed α-helical conformation when mixed with ι-carrageenan.

European Journal of Pharmaceutics and Biopharmaceutics, 2004

The aim of this study is to determine the feasibility of loading biologically active molecules in... more The aim of this study is to determine the feasibility of loading biologically active molecules into templated mesoporous silica (MCM 41). This material shows an important mesoporosity associated to hexagonally organized channels, a narrow pore size distribution and a large surface area. Ibuprofen was selected as a model molecule since it is a well documented and much used anti-inflammatory drug. Furthermore, it has a lipophilic character and its molecular size is suitable for inclusion within the mesopores of the MCM 41 material.

Lasers in Surgery and Medicine, 1997

Background and Objectives: The present study was undertaken to evaluate the feasibility of therma... more Background and Objectives: The present study was undertaken to evaluate the feasibility of thermal damage assessment of blood vessels by using laser-induced release of liposome-encapsulated dye. Study Design/Materials and Methods: Experiments were per-formed in a hamster ...