Metastable Amphiphilic Hydrogels Based on Crosslinked Carboxymethylpullulan

Legros, Mélanie; Cardinaël, Pascal; Dulong, Virginie; Picton, Luc; Cerf, Didier Le

doi:10.1295/polymj.pj2007143

Cited by 3 publications

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References 35 publications

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“…18 We use the second method and dibromohexan to elaborate amphiphilic systems based on carboxymethylpullulan, an anionic derivative of pullulan ( Figure 1). In a recent paper, 19 we showed that the cross-linking reaction was very fast, leading to creation of high crosslink density clusters as described by Hoffman. 20 On the other hand, we demonstrated that dibromohexan gave only crosslinks and not pendant chains as we could expect.…”

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confidence: 82%

“…19,22 The degree of substitution (number of carboxylic groups per anhydroglucose unit) was determined by conductimetric titration according to the method of Eyler 23 and found about 0.96. The average molar masses were determined by F4/MALLS measurements (Table III).…”

Section: Methodsmentioning

confidence: 99%

“…19 Briefly, an aqueous solution of CMP, Na þ was transformed into its acidic form (CMP, H þ ) by elution through a cationic resin (Amberlite IRN-77, H þ form) and then neutralized by tetrabutylammonium hydroxide (Bu 4 N þ , OH À ) up to pH 7. After freeze-drying, the CMP, Bu 4 N þ was dissolved in dimethylsulfoxide (DMSO) at 40 C. Dibromohexan was added under vigorous stirring and the reaction continued at the same temperature during 2 h with magnetic stirring (Figure 2).…”

Section: Synthesis and Chemical Characterization Of Hydrogelsmentioning

confidence: 99%

“…19 The samples were coded as XMIc-Cp with XM: the molar mass of the CMP (LM: Low Mass, MM: Medium Mass), Ic: the incorporation rate of dibromohexan (%) and Cp: the polymer concentration (g L À1 ). In this work, Cp was fixed to 200 g L À1 , Ic was about 20% and only derivatives of MMCMP and LMCMP were studied, i.e., MM20-200 and LM20-200.…”

Section: Synthesis and Chemical Characterization Of Hydrogelsmentioning

confidence: 99%

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Self-organization of Water Soluble and Amphiphile Crosslinked Carboxymethylpullulan

Legros

Dulong

Picton

et al. 2008

Polym J

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The soluble state of amphiphile and crosslinked derivatives of carboxymethylpullulan was investigated by physicochemical analyses. This soluble state also called infinite sol was obtained from hydrogels after a short-time temperature treatment. The analyses show a large distribution in size for the species in solution (from some nanometers to some micrometers). Furthermore, they also reveal the presence of hydrophobic associations (intra and/or intermolecular) in addition to the chemical links. The nature of these hydrophobic interactions will depend on the polymer concentration and on the solvent used.KEY WORDS: Polysaccharide / Crosslinking / Hydrogels / Amphiphile / Self-organization / Hydrogels are suitable materials for drug delivery applications in biomedical and pharmaceutical fields. Indeed, active compounds can be easily entrapped and released, specially by responsive-stimuli devices which undergo phase transition or swelling-deswelling behaviour in response to environmental changes (temperature, pH, ionic strength, . . .). 1-3 Furthermore, they resemble natural living tissues by their ability to absorb and retain huge quantity of fluids and by their consistency, giving them a good biocompatibility. 4 Since several years, numerous studies have been interested in hydrogels based on polysaccharides and their derivatives because of their advantages over synthetic polymers. In fact, they are abundant, largely water soluble, biocompatible and descendent from renewable sources. 5 More recently, attention is focused on the development of amphiphilic networks able to transport amphiphilic and hydrophobic drugs. 6,7 Two majority ways are used to elaborate amphiphilic hydrogels based on polysaccharides. The most widespread way consists in grafting on the polymer backbone hydrophobic chains which self-aggregate in solution so creating cross-linking points but also hydrophobic domains. The most famous examples of this kind of systems are derivatives of pullulan bearing cholesteryl groups (CHP) which provide by self-aggregation particles able to complex hydrophobic molecules and proteins. [8][9][10][11][12][13] An other example consists of carboxymethylpullulan grafting by alkyl pendant groups. 14 The second technique consists in a chemical cross-linking with a hydrophobic agent. Few studies have been interested in this way although it gives in one step cross-links and amphiphilic character. So, Dulong et al. have elaborated amphiphilic carboxymethylpullulan networks using adipic dihydrazide 15 and N-hydroxysuccinimide, 16 whereas Coviello and Matricardi have choosen dibromohexan as cross-linking agent to obtain hydrogels from scleroglucan 17 and polygalacturonic acid. 18 We use the second method and dibromohexan to elaborate amphiphilic systems based on carboxymethylpullulan, an anionic derivative of pullulan (Figure 1). In a recent paper, 19 we showed that the cross-linking reaction was very fast, leading to creation of high crosslink density clusters as described by Hoffman. 20 On the other hand, we demonstrated ...

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confidence: 82%

Section: Methodsmentioning

confidence: 99%

Section: Synthesis and Chemical Characterization Of Hydrogelsmentioning

confidence: 99%

Section: Synthesis and Chemical Characterization Of Hydrogelsmentioning

confidence: 99%

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Self-organization of Water Soluble and Amphiphile Crosslinked Carboxymethylpullulan

Legros

Dulong

Picton

et al. 2008

Polym J

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“…Accessing of metastable assembly states is an interesting domain of materials chemistry research. 11,13,[39][40][41][42][43][44][45] Recently, Wang et al reported a dynamic system where an initially formed metastable transient aggregation is programmed into a thermodynamically more stable hydrogel by aging. 45 In our system, a dynamic covalent bond formation leads to either a thermodynamically stable yellow gel at high pH or a kinetically controlled metastable orange gel at low pH ( Fig.…”

Section: Introductionmentioning

confidence: 99%