NMR Diffusion and Relaxation Studies of the Encapsulation of Fragrances by Amphiphilic Multiarm Star Block Copolymers

Fieber, Wolfgang; Herrmann, Andreas; Ouali, Lahoussine; Velazco, Maria Inés; Kreutzer, Georg; Klok, Harm‐Anton; Ternat, Céline; Plummer, C. J. G.; Månson, Jan‐Anders E.; Sommer, Horst

doi:10.1021/ma070222i

Cited by 28 publications

(32 citation statements)

References 49 publications

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“…For example, Chen et al obtained about 16 nm micelles from hyperbranched multiarm copolymer H 40 -star -(PCLb -PEO) with H 40 cores and PCL-b -PEO block copolymer arms. [ 38 ] Wooley and coworkers reported the preparation of very small micelles around 20 nm from the self-assembly of amphiphilic 19 F-labelled hyperbranched multiarm copolymer HPS-star -PAA with hyperbranched polystyrene (HPS) cores and poly(acrylic acid) (PAA) arms. [ 39 , 40 ] For the latter type, both the hyperbranched polyethylenimine (HPEI) and polyglycerol (HPG) have been used as the core moieties.…”

Section: Self-assembly Of 0d Micellesmentioning

confidence: 99%

“…[ 7 ] Wooley and coworkers have prepared about 20 nm micelles from a 19 F-labeled HPS-star -PAA. [ 40 ] These special polymer micelles can be used as novel 19 F MRI agents for a variety of biomedical studies. To improve the biodegradability and biocompatibility of multimolecular micelles as drug carriers, indotricarbocyanine dye loaded CMS carriers were injected to F9 teratocarcinoma bearing mice for in vivo imaging studies.…”

Section: Multimolecular Micellesmentioning

confidence: 99%

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Self‐Assembly of Hyperbranched Polymers and Its Biomedical Applications

et al. 2010

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Hyperbranched polymers (HBPs) are highly branched macromolecules with a three-dimensional dendritic architecture. Due to their unique topological structure and interesting physical/chemical properties, HBPs have attracted wide attention from both academia and industry. In this paper, the recent developments in HBP self-assembly and their biomedical applications have been comprehensively reviewed. Many delicate supramolecular structures from zero-dimension (0D) to three-dimension (3D), such as micelles, fibers, tubes, vesicles, membranes, large compound vesicles and physical gels, have been prepared through the solution or interfacial self-assembly of amphiphilic HBPs. In addition, these supramolecular structures have shown promising applications in the biomedical areas including drug delivery, protein purification/detection/delivery, gene transfection, antibacterial/antifouling materials and cytomimetic chemistry. Such developments promote the interdiscipline researches among surpramolecular chemistry, biomedical chemistry, nano-technology and functional materials.

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Section: Self-assembly Of 0d Micellesmentioning

confidence: 99%

Section: Multimolecular Micellesmentioning

confidence: 99%

Self‐Assembly of Hyperbranched Polymers and Its Biomedical Applications

et al. 2010

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“…PFG-NMR has already been used as a powerful tool for studies of binding and dynamics in various examples of complex fluids. These include surfactant solutions and microemulsions [26,27], liquid crystals and membranes [28], associating polymers [29], or colloidal encapsulation systems [30][31][32][33][34]. The approach to employ diffusion studies in solubilization problems was pioneered by Stilbs [35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Partitioning and Localization of Fragrances in Surfactant Mixed Micelles

Fischer

Fieber

Navarro

et al. 2008

J Surfact & Detergents

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The localization and dynamics of fragrance compounds in surfactant micelles are studied systematically in dependence on the hydrophobicity and chemical structure of the molecules. A broad range of fragrance molecules varying in octanol/water partition coefficients P ow is employed as probe molecules in an aqueous micellar solution, containing anionic and nonionic surfactants. Diffusion coefficients of surfactants and fragrances obtained by Pulsed Field Gradient (PFG)-NMR yield the micelle/water distribution equilibrium. Three distinct regions along the log(P ow ) axis are identified: hydrophilic fragrances (log(P ow ) \ 2) distribute almost equally between micellar and aqueous phases whereas hydrophobic fragrances (log(P ow ) [ 3.5) are fully solubilized in the micelles. A steep increase of the incorporated fraction occurs in the intermediate log(P ow ) region. Here, distinct micelle swelling is found, while the incorporation of very hydrophobic fragrances does not lead to swelling. The chemical structure of the probe molecules, in addition to hydrophobicity, influences fragrance partitioning and micelle swelling. Structural criteria causing a decrease of the aggregate curvature (flattening) are identified. 2 H-NMR spin relaxation experiments of selectively deuterated fragrances are performed monitoring local mobility of fragrance and leading to conclusions about their incorporation into either micellar interface or micelle core. The tendencies of different fragrance molecules (i) to cause interfacial incorporation, (ii) to lead to a flattening of the micellar curvature and (iii) to incorporate into micelles are shown to be correlated.

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“…(Figure 2b) for the proton at position 1 on the b-(1-4)-3,6-anhydro-D-galactose unit (Figure 1) of k-carrageenan 14 was used for the diffusion analysis. At high temperature, I kappa (0) decreased slightly with decreasing temperature, which is most likely a result of an increase in the viscosity upon cooling, the relaxation time, T 1 and T 2 , values were thus decreased and led to a decrease in I kappa (0) according to Equation (2). At the sol-to-gel transition temperature T sg (28 1C, determined by falling ball method), 12,23 I kappa (0) decreased sharply.…”

Section: Estimation Of the Hydrodynamic Screening Length Q Zhao And Smentioning

confidence: 99%

“…1,2 NMR has proved to be a powerful technique for determining the dynamic and structural properties of food model systems 3 and the gelation process of polysaccharides. 4,5 NMR relaxation times give information about the tumbling motion of molecules in food hydrocolloid systems.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the hydrodynamic screening length in κ-carrageenan solutions using NMR diffusion measurements

Zhao

Matsukawa

2012

Polym J

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We quantify the hydrodynamic screening length (n) in j-carrageenan solutions by observing restrictions on the diffusion of several pullulan probes, each with a different molecular weight (M w ). The diffusion coefficient of pullulan in a pure solvent (D pull,0 ) and a j-carrageenan solution (D pull ) were measured using a pulsed field gradient stimulated spin-echo 1 H nuclear magnetic resonance. The hydrodynamic radii (R H ) of the pullulan samples were determined using D pull,0 measured at 25 1C and the Stoke-Einstein equation. The echo signal intensity of j-carrageenan without a gradient, I kappa (0), decreased steeply at around the sol-to-gel transition temperature (T sg ), suggesting that the j-carrageenan chains formed helical aggregates at T sg diluting the solute j-carrageenan concentration. The ratio, D pull /D pull,0 , was less than 1, indicating that the mobility of pullulan was restricted by the j-carrageenan chains. Over the entire temperature range, pullulan with larger molecular size yielded more restrictions on the molecular mobility, and D pull /D pull,0 decreased as the M w of pullulan increased. Below T sg , D pull /D pull,0 increased as the temperature decreased. This behavior suggests that a decrease in the restriction degree by the j-carrageenan chains is concomitant with the formation of aggregates. To quantify the restriction degree, n was estimated at various temperatures using the relation D pull /D pull,0 ¼ exp( ÀR H /n). Polymer Journal ( Keywords: diffusion coefficient; gel; gradient NMR; hydrodynamic radius; hydrodynamic screening length; pullulan; k-carrageenan INTRODUCTIONThe diffusion of solutes in a gel matrix has an important role in applications such as the delivery of drugs and the encapsulation of fragrances. 1,2 NMR has proved to be a powerful technique for determining the dynamic and structural properties of food model systems 3 and the gelation process of polysaccharides. 4,5 NMR relaxation times give information about the tumbling motion of molecules in food hydrocolloid systems. The diffusion coefficients determined by pulsed-field-gradient NMR reflect the translational motion of molecules. The diffusion coefficient of solutes in a polymer matrix strongly depends on molecular weight, temperature, viscosity and the network structure of the diffusing matrix. Any factor that reduces the space delineated by the polymer chains will have an effect on the molecular mobility of the solute. In polysaccharide gels, the aggregation of polysaccharide chains can enlarge the diffusing space. Therefore, to understand the diffusion of molecules in a gel, it is important to understand the aggregation behavior.k-Carrageenan is a linear sulfated polysaccharide that is extracted from marine red algae. As shown in Figure 1, k-carrageenan comprises two galactose units: a-(1-3)-D-galactose-4-sulfate and b-(1-4)-3,6-anhydro-D-galactose. It is a gelling agent that has

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NMR Diffusion and Relaxation Studies of the Encapsulation of Fragrances by Amphiphilic Multiarm Star Block Copolymers

Cited by 28 publications

References 49 publications

Self‐Assembly of Hyperbranched Polymers and Its Biomedical Applications

Self‐Assembly of Hyperbranched Polymers and Its Biomedical Applications

Partitioning and Localization of Fragrances in Surfactant Mixed Micelles

Estimation of the hydrodynamic screening length in κ-carrageenan solutions using NMR diffusion measurements

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