Altering Associations in Aqueous Solutions of a Hydrophobically Modified Alginate in the Presence of β-Cyclodextrin Monomers

Galant, Céline; Kjøniksen, Anna–Lena; Nguyen, Giao T.M.; Knudsen, Kenneth D.; Nyström, Bo

doi:10.1021/jp0518759

Cited by 70 publications

(64 citation statements)

References 28 publications

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“…A similar inversion of G′ and G″ for higher angular frequencies was previously observed for anionic polystyrenes (Chang 1986). According to the literature, the storage modulus (G′) is directly proportional to the number of active junctions between polymer chains (Galant et al 2006). Indeed, when no shear or deformation is applied, alginate chains build up a physical gel based on strong interaction or association between the alginate chains, leading to a higher value of storage modulus (G′).…”

Section: Discussionmentioning

confidence: 99%

Extracted and depolymerized alginates from brown algae Sargassum vulgare of Lebanese origin: chemical, rheological, and antioxidant properties

et al. 2015

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International audiencePurified sodium alginate (PS alginate) was isolated from the brown seaweed Sargassum vulgare collected from the Lebanese Mediterranean coast and then depolymerized into homopolymeric polyguluronate (PolyG) and polymannuronate (PolyM) blocks by controlled acid hydrolysis. These fractions of PS alginate issued from S. vulgare were characterized in terms of composition and structure by SEC, elemental analysis, FTIR and 1H and 13C NMR spectroscopy. An alginate with a low content of protein (\textless0.62 %) and a molecular weight of 110 200 g mol-1 was identified as sole polysaccharide. Depolymerized PS alginate fractions, PolyG (32.6 %) and PolyM (22.3 %), were found to have close molecular weights, of 7500 and 6900 g mol-1, respectively. From NMR analysis, values of F G, F M, M/G ratio, F GG, F MM, and F GM (or F MG) blocks were determined and compared with those of alginates from S. vulgare of Brazilian origin and other Sargassum species. Our PS alginate appeared different from the Brazilian S. vulgare alginate, with a lower M/G ratio (0.785 instead of 1.27), a predominance of the G blocks (F G and F GG \textgreater 0.5) instead of the M blocks, and it showed more similarity to the composition of some alginates extracted from other species of Sargassum. High G or M contents (≥80 %) were measured from PolyG and PolyM blocks, respectively. The viscosity of the PS alginate and its fractions PolyG and PolyM was determined. PS alginate from S. vulgare of Lebanese origin showed a Newtonian flow behavior for concentration lower than 0.5 % in 0.1 M NaCl solution, while a shear-thinning pseudoplastic behavior is observed for concentration range between 0.75 and 10 %. Also, storage (G′) and loss (G″) moduli were studied for two concentrations of PS alginate solutions (5 and 10 %). Antioxidant properties of the non-depolymerized and depolymerized alginates were evaluated by determining the scavenging ability of the stable radical DPPH (2,2-diphenyl-1 picrylhydrazyl). Clearly, the results demonstrated differences in radical scavenging efficacy between PolyG and PolyM fractions. The higher hydroxyl radical scavenging activity was observed for the PolyG fractions (~92 % at 2 mg mL-1) and this activity was comparable with those of standard antioxidants. These PolyG fractions could be valuable in foods or pharmaceutical products as alternatives to synthetic antioxidant

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Section: Discussionmentioning

confidence: 99%

Extracted and depolymerized alginates from brown algae Sargassum vulgare of Lebanese origin: chemical, rheological, and antioxidant properties

et al. 2015

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“…Amphiphilic alginate derivative (AAD) was synthesized by the amidation through alginate coupling with octylamine in the presence of EDCÁHCl [23,[33][34][35]. The amidation reaction was carried out through the following steps.…”

Section: Synthesis and Characterization Of Aadmentioning

confidence: 99%

“…The results could be explained by the facts that the amidation of SA could enhance its affinity to the hydrophobic drug and facilitate the formation of the drug-loaded nanocapsules, which was significant for the sustained release of kcyhalothrin. Meanwhile, the amidation modification of alginate is widely used in biomedical application and tissue engineering as a result of its biocompatibility and nontoxicity for humans [33,34]. Thus, the electrospun AAD/PVA blend nanofibers were good candidates for use in biomedical applications due to their drug-loading and sustained release properties.…”

Section: Release Studiesmentioning

confidence: 99%

Synthesis of amphiphilic alginate derivatives and electrospinning blend nanofibers: a novel hydrophobic drug carrier

et al. 2015

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As a kind of novel hydrophobic drug carrier materials, the drug-loaded nanofibers were successfully fabricated using amphiphilic alginate derivative (AAD) and poly (vinyl alcohol) (PVA) by electrospinning method. The AAD was synthesized by amide linkage attachment of octylamine onto the carboxylic group of alginate, which was characterized by the means of elemental analysis, FT-IR spectrometer, 1 H NMR spectrometer and fluorescence measurement. Experimental results showed the amidation of alginate was successful, in which the degree of modification was 0.27 and the critical aggregation concentration in 0.15 mol/L aqueous NaCl solution was 0.43 mg/mL. The octyl groups of AAD could effectively make alginate chains flexible and enhance chain entanglements through the hydrophobic interactions between octyl groups. In contrast to sodium alginate (SA)/ PVA blend solutions, AAD/PVA blend solutions showed more excellent electrospinnability. Additionally, the different volume ratios of SA or AAD to PVA played an important role in the formation and morphology of the electrospun blend nanofibers. Although the amidation of alginate could not fundamentally alter the spinnability of alginate, the content of alginate in the blend nanofibers was appropriately increased. The new generated drug-loaded AAD/PVA (20/80) blend nanofibers exhibited relatively continuous and uniform nanofibers with the average diameter of 191.72 nm. Compared to the drug-loaded SA/PVA (20/80) blend nanofibers, the drug-loaded AAD/PVA (20/80) blend nanofibers presented a sustained release performance with the slow release of about 76 % k-cyhalothrin during the initial period of 10 h.

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“…Through derivatization of alginate derivatives by functionalizing available hydroxyl and carboxyl groups, the properties such as solubility, hydrophobicity and physicochemical and biological characteristics may be modified. Several chemical modifications of Alginate were reviewed by authors including; Acylation [14], Sulfation [15], phosphorylation [16], Oxidation [17], Reductive-amination [18], Amidation [19], Copolymerization [20], alkyl sulfonation [21] etc.…”

Section: Issn: 2320-5407mentioning

confidence: 99%

Functionalization of Alginate via Phosphorization: Preparation, Characterization.

Taleb¹,

Roston²,

Mohyeldin³

et al. 2017

IJAR

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Altering Associations in Aqueous Solutions of a Hydrophobically Modified Alginate in the Presence of β-Cyclodextrin Monomers

Cited by 70 publications

References 28 publications

Extracted and depolymerized alginates from brown algae Sargassum vulgare of Lebanese origin: chemical, rheological, and antioxidant properties

Extracted and depolymerized alginates from brown algae Sargassum vulgare of Lebanese origin: chemical, rheological, and antioxidant properties

Synthesis of amphiphilic alginate derivatives and electrospinning blend nanofibers: a novel hydrophobic drug carrier

Functionalization of Alginate via Phosphorization: Preparation, Characterization.

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