References of "Riva, Raphaël"
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See detailChitosan: a versatile platform for pharmaceutical applications
Riva, Raphaël ULg; Jérôme, Christine ULg

in Material Matters: Chemistry Driving Performance (2014), 9(3), 95-98

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See detailReversibly cross-linked polymer micelle as smart drug dellivery device
Lecomte, Philippe ULg; Riva, Raphaël ULg; Cajot, Sébastien et al

Conference (2013, November 20)

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See detailDrug delivery systems based on amphiphilic polyphosphate-copolymers
Vanslambrouck, Stéphanie ULg; Clement, Benoît ULg; Riva, Raphaël ULg et al

Poster (2013, September 18)

Thanks to their biocompatibility, biodegradability and their structure similar to natural biomacromoleculesn such as nucleic acids, polyphosphates (PPhos) are of prime interest as biomaterials. In ... [more ▼]

Thanks to their biocompatibility, biodegradability and their structure similar to natural biomacromoleculesn such as nucleic acids, polyphosphates (PPhos) are of prime interest as biomaterials. In contrast to poly--caprolactone and polylactides, PPhos properties and functionality are easily tuned via the nature of the pendant group of the starting cyclic monomer. For example, by varying the length of the alkyl chain the hydrophobicity of the PPhos can be adjusted. In this work, an efficient organo-catalytic system was developed to synthesize a series of amphiphilic diblock copolymers, i.e. poly(ethylene oxide)-b-polyphosphate (PEO-b-PPhos) by ring-opening polymerization of cyclic phosphates. This novel approach prevents metallic residues to polute the final product, and which is highly desirable when biomedical applications are foreseen. For drug delivery application, the micellization of these novel diblock copolymers in aqueous media was investigated, as well as, encapsulation of an hydrophobic drug. Data on, the influence of the polyphosphate nature of the polymer on drug loading will be presented. [less ▲]

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See detailTailor made amphiphilic copolymers for the design of smart drug delivery systems
Riva, Raphaël ULg; Cajot, Sébastien; Jérôme, Christine ULg

Conference (2013, August 21)

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See detailShape-memory materials based on thermoreversibly cross-linked poly-ε-caprolactones
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

Poster (2013, August 19)

Shape memory polymers (SMPs) are materials that are able to change their shape from a temporary shape to a permanent one by application of a stimulus such as heat or light. SMPs are usually chemically or ... [more ▼]

Shape memory polymers (SMPs) are materials that are able to change their shape from a temporary shape to a permanent one by application of a stimulus such as heat or light. SMPs are usually chemically or physically crosslinked materials that exhibit an elastomeric behaviour above a glass or melting transition temperature. Poly(ε-caprolactone) (PCL) is one of the most widely studied polymers for the development of SMPs. PCL presents several advantages such as a melting transition temperature close to human body temperature, a high biocompatibility, is (bio)degradable and potentially biosourced. So, this polymer is highly relevant for both degradable packaging and also for biomedical devices such as resorbable suture wires or stents. However, after crosslinking, the material can not be reprocessed, preventing any reuse/recycling. The main purpose of this work is to provide a solution to this major drawback, which would then enable, for example, to reshape packaging films after use or to reprocess trimmings remaining after production. Amongst current trends in the design of new polymer and composite materials, organic reactions that are able to create and reversibly disrupt chemical bonds upon an external stimulus (temperature, irradiation,…) are currently gaining more and more attention in macromolecular engineering and are used in various areas such as remendable materials, drug delivery systems, stimulus-degrading materials or recyclable materials. Amongst all the reversible links described in the literature, thermally (4+2) reversible cycloadditions present interesting properties such as the creation of robust bonds and well defined reversibility conditions. As an example, the application of furan/maleimide adducts as covalent link, which cycloreversion is largely favored in the range of temperature (90-120°C), is widely reported. This contribution aims at reporting a new concept for the preparation of well defined and recyclable PCL based reversibly cross-linked SMPs by the formation of reversible carbon-carbon bonds. For this purpose, commercially-available linear and multi-arm star shaped PCL precursors have been selected and selectively functionalized at their chain ends either by a diene (furan, anthracene) or a dienophile (maleimide). Typically, PCL-based shape memory materials have been prepared by mixing a stoichiometric amount of diene-bearing and maleimide-bearing PCLs in a twin-screw mini-extruder at a temperature which favors cycloreversion. The polymer blend is then cured at 65°C (just above PCL melting temperature), with the purpose to increase chains mobility and improve the formation of the adducts. Cross-linked PCLs were obtained, as evidenced by swelling experiments. The shape memory properties of the materials have been studied by cyclic tensile thermomechanical analysis. The influence of the architecture of the PCL precursors as well as the nature of the Diels-Alder moieties on the cross-linking rate and on the shape memory properties has been studied. Reversibility of the network formation in the case of furan, used as diene, has been assessed by rheology and by recycling experiment. [less ▲]

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See detailDevice-based controlled local delivery for the treatment of peritoneal pathologies
Riva, Raphaël ULg; Krier, Fabrice; Defrère, Sylvie et al

Poster (2013, August 18)

This contribution aims at reporting the developpment of a controlled drug delivery system (DDS) dedicated to the treatment of intra-peritoneal pathologies, especially endometriosis. At present time ... [more ▼]

This contribution aims at reporting the developpment of a controlled drug delivery system (DDS) dedicated to the treatment of intra-peritoneal pathologies, especially endometriosis. At present time, endometriosis is generally treated by daily oral absorption of drug with the purpose to improve the life quality of patients by the reduction of the pain caused by endometrial lesions. Nevertheless, deleterious side-effects, mainly infertility, are observed as a consequence of the important amount of absorbed active principle. One main advantage of controlled drug delivery devices, e.g. polymer implants, is to maintain sustained drug release over a prolonged period of time thereby eliminating fluctuations in the drug plasma concentration. Moreover, DDS allows a local release of the drug at a specific area, which significantly decreases the active principle concentration in the body and limits side-effects. The peritoneal cavity is a convenient site for the implantation of a DDS against endometriosis because large parts of lesion are localized in this region. At our knowledge, no application of an implant dedicated to the treatment of endometriosis is reported in the literature, whereas the local controlled release of an active principle presents several advantages compared to systemic administration. In this study, anastrozole (2,2’-[5-1H-1,2,4-triazole-1-yl-methyl)-1,3-phenylene]bis(2-methylpropiononitrile)), a well-known aromatase-inhibiting drug, was selected as active molecule. Typically, two non-biodegradable polymers were tested for the elaboration of an anastrozole loaded intra-peritoneal implant, namely polydimethylsiloxane (PDMS) and poly(ethylene-co-vinyl acetate) (EVA). As preliminary research, the ‘in vivo’ biocompatibility of PDMS and EVA in the intra-peritoneal cavity was confirmed by implantation of PDMS and EVA rod-shaped implants in rats. The kinetic of release was determined ‘in vitro’ and confirmed ‘in vivo’. Besides, the efficiency of the implants was improved by the addition of a polymer membrane, which allowed a controlled release of anastrozole over a period of 400 days. [less ▲]

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See detailThermoreversibly cross-linked poly-ε-caprolactones for the elaboration of shape memory materials
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

Poster (2013, April 19)

This contribution aims at reporting a new concept for the preparation of well defined and recyclable PCL- based reversibly cross-linked shape memory polymer by the formation of reversible carbon-carbon ... [more ▼]

This contribution aims at reporting a new concept for the preparation of well defined and recyclable PCL- based reversibly cross-linked shape memory polymer by the formation of reversible carbon-carbon bonds. For this purpose, commercially-available star-shaped PCL precursors were selected and selectively modified at their chain ends either by a diene (furan) or a dienophile (maleimide). PCL-based shape memory materials were prepared by mixing a stoichiometric amount of diene-bearing and maleimide-bearing PCLs at a temperature which favors cycloreversion. The polymer blend is then cured at 65°C (slightly above PCL melting temperature), with the purpose to increase chains mobility and improve the formation of the adducts. The Diels-Alder kinetics has been followed by Raman spectroscopy and the PCL cross-linking was evidenced by both swelling experiments and rheological measurements. The obtained cross-linked PCL was characterized by shape memory properties with excellent fixity and recovery, as determined by cyclic tensile thermomechanical analysis. [less ▲]

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See detailNovel functional degradable block copolymers for the building of reactive micelles
Cajot, Sébastien; Lecomte, Philippe ULg; Jérôme, Christine ULg et al

in Polymer Chemistry (2013), 4(4), 1025-1037

Amphiphilic biocompatible copolymers are promising materials for the elaboration of nanosystems for drug delivery applications. This paper aims at reporting on the synthesis of new functional amphiphilic ... [more ▼]

Amphiphilic biocompatible copolymers are promising materials for the elaboration of nanosystems for drug delivery applications. This paper aims at reporting on the synthesis of new functional amphiphilic copolymers based on biocompatible and bioeliminable blocks. Poly(ethylene oxide) was selected as the hydrophilic block, whereas an aliphatic polyester, i.e. poly(epsilon-caprolactone), or a polycarbonate, i.e. poly(trimethylene carbonate), were chosen as the degradable hydrophobic block. In order to allow a post-functionalization of the micelles core, azide groups were introduced on the hydrophobic segment to provide reactivity towards functional alkyne derivatives by the copper azide-alkyne cycloaddition (CuAAC). For this purpose, a functional lactone, i.e. alpha-chloro-epsilon-caprolactone was introduced during the polymerization of the hydrophobic block before being converted into azide on the preformed copolymer. Such reactivity of the block copolymers and their self-assemblies is of prime interest for drugs or fluorescent dyes grafting, so as for micelles cross-linking. The influence of the azides distribution along the degradable block on the micelles post-functionalization ability has been studied by using alkyne bearing fluorescent dyes as model for drugs. The hydrophilicity of the dye on the micelles post-functionalization efficiency has also been investigated. [less ▲]

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See detailFunctional degradable polymers for advanced drug delivery systems
Cajot, Sébastien; Riva, Raphaël ULg; Jérôme, Christine ULg

Conference (2012, September)

Nowadays, polymer micelles have attracted an increasing interest in pharmaceutical research because they could be used as efficient drug delivery systems. Micelles of amphiphilic block copolymers are ... [more ▼]

Nowadays, polymer micelles have attracted an increasing interest in pharmaceutical research because they could be used as efficient drug delivery systems. Micelles of amphiphilic block copolymers are supramolecular core-shell type assemblies of several tens of nanometers in diameter. In principle, the micelle core is usually constructed with biodegradable hydrophobic polymers such as aliphatic polyesters, e.g. poly(ε-caprolactone) (PCL), which serves as a reservoir for the incorporation of various lipophilic drugs. Water soluble poly(ethylene oxide) (PEO) is most frequently used to build the micelle corona because it is very efficient in preventing protein adsorption at surfaces and in stabilizing micelles in the blood compartment, making particles invisible to the body defense system. Even if micelles get a high stability in aqueous media thanks to their low critical micellar concentration, micelle dissociation is not always preserved when they are injected in the blood compartment. A way to provide the micelle stability during their administration is to cross-link them. Different kinds of cross-linked micelles can be investigated depending on the localization of the cross-linking. Shell cross-linked micelles or nanocage structures with a degradable core have the great advantage to reach drug encapsulation with a high loading rate. However, cross-linking the hydrophilic shell may affect the stealthiness of the carrier. Thus, we have designed reversibly cross-linked micelles by introducing the cross-linking bridges in the hydrophobic segment of the block copolymer, rather than in the hydrophilic one, leading so to more internal cross-linking and thus preserving the mobility of the hydrophilic segment. Three different localizations of the cross-linking has been targeted; (i) loose core cross-linking of a core-corona system, (ii) tight core cross-linking of a core-shell-corona system (the shell and the core being both hydrophobic and the corona hydrophilic) and (iii) tight shell cross-linking of a similar core-shell-corona system. To reach this goal, three types of amphiphilic copolymers have been used bearing pendent azide groups in the hydrophobic segment. These copolymers have been obtained by starting the ring-opening polymerization of ε-CL and a functional CL, either as a mixture or sequentially from a poly(ethylene oxide) macroinitiator leading to the three targeted architectures. The azide groups located along the PCL backbone have then been used to cross-link the micelles by the Huisgens cycloaddition with a bis-alkyne cross-linker. The choice of this cross-linker has also taken into account the requirement to make the cross-linking reversible. For that purpose, disulfide bridges have been selected in order to impart reversibility to the cross-linking by intracellular reduction. Indeed, the marked concentration difference of glutathione between extra- and intra-cellular environments has already been used to trigger drug release by intracellular disulfide bond cleavage. Accordingly, a bis-alkyne disulfide molecule has been chosen as cross-linker. The micellization and cross-linking of these amphiphilic azido macromolecules have been studied. The reversibility of the cross-linking in reductive environment and the cross-linked micelles stealthiness have been tested. [less ▲]

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See detailImplant comprising a core and a tube encasing the core
Donnez, Jacques; Van Langendonkt, Anne; Defrère, Sylvie et al

Patent (2012)

The present invention relates to an implant comprising: - a core material comprising polydimethylsiloxane or at least one hydrogel polymer; - a tube encasing said core material comprising an ethylene ... [more ▼]

The present invention relates to an implant comprising: - a core material comprising polydimethylsiloxane or at least one hydrogel polymer; - a tube encasing said core material comprising an ethylene vinyl acetate polymer or at least one hydrogel polymer; - a sealant for closure of the open ends of said tube comprising polydimethylsiloxane or a mono-, di-, or triacetoxy derivative thereof, or at least one hydrogel polymer; and - at least one active ingredient; wherein said at least one active ingredient is selected from the group comprising celecoxib, sulindac, tamoxifen, oestrogen, oestradiol, ethinyl oestradiol, mestranol, dienogest, norgestrel, levonorgestrel, desogestrel, norgestimate, ethynodiol diacetate, leuprorelin, buserelin, gonrelin, triptorelin, nafarelin, deslorelin, histrelin, and supprelin; and with the proviso that when the sealant is said at least one hydrogelpolymer, the core material comprises polydimethylsiloxane. Furthermore, the invention relates to an implant for use as a medicament. In particular, the invention relates to an implant for use in the treatment of endometriosis. [less ▲]

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See detailImplant comprising a core and a tube encasing the core
Donnez, Jacques; Van Langendonkt, Anne; Defrère, Stéphanie et al

Patent (2012)

The present invention relates to an implant comprising: - a core material comprising polydimethylsiloxane or at least one hydrogel polymer; - a tube encasing said core material comprising an ethylene ... [more ▼]

The present invention relates to an implant comprising: - a core material comprising polydimethylsiloxane or at least one hydrogel polymer; - a tube encasing said core material comprising an ethylene vinyl acetate polymer or at least one hydrogel polymer; - a sealant for closure of the open ends of said tube comprising polydimethylsiloxane or a mono-, di-, or triacetoxy derivative thereof, or at least one hydrogel polymer; and - at least one active ingredient; with the proviso that when the sealant is said at least one hydrogel polymer, the core material comprises polydimethylsiloxane. Furthermore, the invention relates to an implant for use as a medicament. In particular, the invention relates to an implant for use in the treatment of endometriosis. [less ▲]

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See detailSynthesis of novel poly(N-vinyl amide)s containing copolymers by cobalt-mediated radical polymerization
Kermagoret, Anthony ULg; Hurtgen, Marie ULg; Liu, Ji ULg et al

Poster (2012, May 10)

Poly(N-vinyl amide)s are found in many applications due to their valued properties including water solubility, biocompatibility, metal-coordination ability, etc. Although N-vinyl amides are easily ... [more ▼]

Poly(N-vinyl amide)s are found in many applications due to their valued properties including water solubility, biocompatibility, metal-coordination ability, etc. Although N-vinyl amides are easily polymerized via radical pathways, their growing radicals are quite reactive due to the lack of stabilizing group, rendering the synthesis of well-defined poly(N-vinyl amide)s challenging. Thus, we explored the organometallic-mediated radical polymerization (OMRP) of a series of N-vinyl amides using bis(acetylacetonato)cobalt(II) as controlling agent in order to develop a platform for the precision synthesis of poly(N-vinyl amide)s. [less ▲]

Detailed reference viewed: 80 (8 ULg)