References of "Riva, Raphaël"
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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 ▲]

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See detailCrosslinking of star-shape PCLs through Diels-Alder reactions for the preparation of shape memory polymers
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

Poster (2012, May 10)

Poly(ε-caprolactone) (PCL), a semi-crystalline polymer, is one of the most widely studied polymers for the development of shape memory materials when chemically cross-linked. PCL presents several ... [more ▼]

Poly(ε-caprolactone) (PCL), a semi-crystalline polymer, is one of the most widely studied polymers for the development of shape memory materials when chemically cross-linked. PCL presents several advantages such as a melting transition temperature close to human body temperature, a high biocompatibility and is (bio)degradable. So, this polymer is highly relevant for both biomedical devices such as stents or resorbable suture wires and also for degradable packaging. However, after cross-linking, the material can not be reprocessed, preventing any reuse/recycling of the material. One of the purposes of this work is to find a solution to this major drawback, which would then allow, for example, to reshape packaging films after use or to recycle trimmings remaining after fabrication. Amongst current trends in the design of new polymer and composite materials, the use of organic reactions that are able to create and reversibly disrupt chemical bonds upon an external stimulus (temperature, irradiation,…) is currently gaining more and more attention as it can lead to applications in various areas such as remendable materials, drug delivery systems, stimulus-degrading materials or recyclable materials. 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. Amongst all the reversible links described in the literature, thermally (4+2) reversible cycloadditions present interesting features 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. For this purpose, commercially-available star-shaped PCL precursors have been selected and selectively modified 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 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 detailTocol modified glycol chitosan for the oral delivery of poorly soluble drugs
Duhem, Nicolas; Rolland, Julien; Riva, Raphaël ULg et al

in International Journal of Pharmaceutics (2012), 423(2), 452-460

The aim of this study was to develop tocol derivatives of chitosan able (i) to self-assemble in the gastrointestinal tract and (ii) to enhance the solubility of poorly soluble drugs. Among the derivatives ... [more ▼]

The aim of this study was to develop tocol derivatives of chitosan able (i) to self-assemble in the gastrointestinal tract and (ii) to enhance the solubility of poorly soluble drugs. Among the derivatives synthesized, tocopherol succinate glycol chitosan (GC-TOS) conjugates spontaneously formed micelles in aqueous solution with a critical micelle concentration of 2 μg mL−1. AFM and TEM analysis showed that spherical micelles were formed. The GC-TOS increased water solubility of 2 model class II drugs. GC-TOS loading efficiency was 2.4% (w/w) for ketoconazole and 0.14% (w/w) for itraconazole, respectively. GC-TOS was non-cytotoxic at concentrations up to 10 mg mL−1. A 3.4-fold increase of the apparent permeation coefficient of ketoconazole across a Caco-2 cell monolayer was demonstrated. Tocol polymer conjugates may be promising vehicles for the oral delivery of poorly soluble drugs. [less ▲]

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See detailMultifunctional poly( ε-caprolactone)-forming networks by Diels–Alder cycloaddition: effect of the adduct on the shape-memory properties
Defize, Thomas ULg; Riva, Raphaël ULg; Jérôme, Christine ULg et al

in Macromolecular Chemistry and Physics (2012), 213(2), 187-197

Star-shaped poly(e-caprolactone)s are functionalized by various dienes (furan and anthracene) and a dienophile (maleimide), and the kinetics of network formation by melt-blending is compared for both ... [more ▼]

Star-shaped poly(e-caprolactone)s are functionalized by various dienes (furan and anthracene) and a dienophile (maleimide), and the kinetics of network formation by melt-blending is compared for both Diels–Alder adducts. When curing at 60 °C, the anthracene–maleimide network forms more rapidly and gives rise to a more crosslinked material than with the furan–maleimide adduct. Shape-memory properties of the networks are compared in terms of Diels–Alder adduct stability. Both materials exhibit excellent fixity and recovery ratios, but the relatively low retro Diels–Alder temperature of the furan–maleimide adduct perturbs the mechanical stability of the network during cyclic tensile testing between 0 and 60 °C, whereas the anthracene–maleimide adduct is shown to be stable up to 150 °C. [less ▲]

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See detail"Click chemistry" to derived antimicrobial polymers
Lecomte, Philippe ULg; Riva, Raphaël ULg; Jérôme, Christine ULg

in Lagaron, José Maria; Ocio Zapata, Maria José; Lopez-Rubio, Amparo (Eds.) Antimicrobial polymers (2012)

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See detailThermo-reversible reactions for the preparation of smart materials: recyclable covalently-crosslinked shape memory polymers
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

in Macromolecular Symposia (2011), 309/310(1), 154-161

[4+2] thermoreversible Diels-Alder cycloaddition has been used to crosslink star-shaped poly(ε-caprolactone) in order to produce networks based on strong carbon-carbon covalent bondings. Depending on the ... [more ▼]

[4+2] thermoreversible Diels-Alder cycloaddition has been used to crosslink star-shaped poly(ε-caprolactone) in order to produce networks based on strong carbon-carbon covalent bondings. Depending on the nature of the Diels-Alder reactants, these bonds can be thermoreversibly broken, allowing re-processing of the polymer matrix. [less ▲]

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See detailNovel amphiphilic mikto-arm star-shaped copolymers for the preparation of PLA-based nanocarriers
Cajot, Sébastien ULg; Riva, Raphaël ULg; Billiet, Leen et al

in Macromolecular Symposia (2011), 309/310(1), 111-122

Three-arm (A2B) and four-arm (A2B2) star-shaped copolymers based on biocompatible and biodegradable hydrophobic poly(ε-caprolactone) (PCL) (A arms) and biocompatible and bioeliminable hydrophilic poly ... [more ▼]

Three-arm (A2B) and four-arm (A2B2) star-shaped copolymers based on biocompatible and biodegradable hydrophobic poly(ε-caprolactone) (PCL) (A arms) and biocompatible and bioeliminable hydrophilic poly(ethylene oxide) (PEO) (B arms) were synthesized by the coupling of an ω-azide terminated PEO chains with PCL chain bearing one (A2B) or two (A2B2) alkyne functions at the middle of the chain by the copper mediated azide-alkyne cycloaddition (CuAAC). The amphiphilic behavior of these different stars was confirmed by micellization experiments in water followed by dynamic light scattering and transmission electron microscopy analyses. The efficiency to stabilize PLA nanoparticles was investigated in function of the stars structure. [less ▲]

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See detailNew functional poly(N-vinylpyrrolidone) based (co)polymers via photoinitiated cobalt-mediated radical polymerization
Debuigne, Antoine ULg; Schoumacher, Matthieu ULg; Willet, Nicolas ULg et al

in Chemical Communications (2011), 47(47), 12703-12705

The photoinitiated cobalt-mediated radical polymerization enables the synthesis of novel alpha-functional and alpha,omega-telechelic polymers. In combination with ring-opening polymerization, it also ... [more ▼]

The photoinitiated cobalt-mediated radical polymerization enables the synthesis of novel alpha-functional and alpha,omega-telechelic polymers. In combination with ring-opening polymerization, it also produces new amphiphilic copolymers which self-assemble into flower-like vesicles in water. [less ▲]

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See detailThermoreversibly crosslinked poly(ε-caprolactone) as recyclable shape-memory polymer network
Defize, Thomas ULg; Riva, Raphaël ULg; Raquez, Jean-Marie et al

in Macromolecular Rapid Communications (2011), 32(16), 1264-1269

A new concept to build shape memory polymers (SMP) combining outstanding fixity and recovery ratios (both above 99% after only one training cycle) typical of chemically crosslinked SMPs with ... [more ▼]

A new concept to build shape memory polymers (SMP) combining outstanding fixity and recovery ratios (both above 99% after only one training cycle) typical of chemically crosslinked SMPs with reprocessability restricted to physically crosslinked SMPs is demonstrated by covalently bonding, through thermoreversible Diels–Alder (DA) adducts, star-shaped poly(epsilon-caprolactones) (PCL) end-functionalized by furan and maleimide moieties. A PCL network is easily prepared by melt-blending complementary end-functional star polymers in retro DA regime, then by curing at lower temperature to favour the DA cycloaddition. Such covalent network can be reprocessed when heated again at the retro DA temperature. The resulting SMP shows still excellent shape memory properties attesting for its good recyclability. [less ▲]

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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 detailPreparation of pH-sensitive star-shaped aliphatic polyesters as precursors of polymersomes
Riva, Raphaël ULg; Lazzari, Wenda; Billiet, Leen et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2011), 49(7), 1552-1563

The synthesis of a new pH-sensitive amphiphilic A2B mikto-arm star-shaped aliphatic copolyester (with A = PCL and B = tertiary amine-bearing PCL) with two hydrophobic arms and one hydrophilic arm when ... [more ▼]

The synthesis of a new pH-sensitive amphiphilic A2B mikto-arm star-shaped aliphatic copolyester (with A = PCL and B = tertiary amine-bearing PCL) with two hydrophobic arms and one hydrophilic arm when protonated at pH = 5.5. The copper mediated azide-alkyne cycloaddition was used for the synthesis of the star copolyester and to impart the pH sensitivity to the hydrophilic arm by grafting of tertiary amine groups onto azide bearing PCL chain. The formation of polymersomes in water at pH 5 was assessed by DLS and TEM analyses. [less ▲]

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See detailIn vivo biocompatibility of three potential intraperitoneal implants
Defrère, Sylvie; Mestdagt, Mélanie ULg; Riva, Raphaël ULg et al

in Macromolecular Bioscience (2011), 11(10), 1335-45

The intraperitoneal biocompatibility of PDMS, polyHEMA and pEVA was investigated in rats, rabbits and rhesus monkeys. No inflammation was evidenced by hematological analyses and measurement of ... [more ▼]

The intraperitoneal biocompatibility of PDMS, polyHEMA and pEVA was investigated in rats, rabbits and rhesus monkeys. No inflammation was evidenced by hematological analyses and measurement of inflammatory markers throughout the experiment and by post-mortem examination of the pelvic cavity. After 3 or 6 months, histological analysis revealed fibrous tissue encapsulating PDMS and PEVA implants in all species and polyHEMA implants in rabbits and monkeys. Calcium deposits were observed inside polyHEMA implants. The intraperitoneal biocompatibility of all 3 polymers makes them suitable for the design of drug delivery systems, which may be of great interest for pathologies confined to the pelvic cavity. [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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