Thermoreversible gelation of κ-Carrageenan: relation between conformational transition and aggregation

Mangione, Maria Rosalia; Giacomazza, Daniela; Bulone, Donatella; Martorana, Vincenzo; Biagio, Pier Luigi San

doi:10.1016/s0301-4622(02)00341-1

Cited by 141 publications

(76 citation statements)

References 23 publications

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“…Under the chosen experimental conditions, the incorporation of a drug in sodium salt form does not seem to change the gelation mechanism discussed in details in previous works [9][10]. The structural and visco-elastic characteristics of gels can be controlled by the K + / Na + ions composition.…”

Section: Discussionmentioning

confidence: 74%

“…In the case of κ-carrageenan, K + and Na + ions play a fundamental role in establishing the gelation pathway [9][10]. Previous studies, performed on gels without drug [10], have shown that it is possible, by using an…”

Section: Resultsmentioning

confidence: 99%

“…The κ-Carrageenan powder was dissolved in Millipore deionised water at 70 °C (in the presence of 200 ppm sodium azide as bacteriostatic agent) and stirred at the same temperature for 2 h. [9,11]. The pH of the solution was 8.7 to prevent hydrolysis during preparation [11][12].…”

Section: Methodsmentioning

confidence: 99%

“…Previous studies on κ-carrageenan gels have shown that the internal structure of the gel can be easily and opportunely modulated using different proportions of K + and Na + ions [9][10]. In fact, these cations play a different and specific role in the κ-carrageenan gelation pathway: the K + induces a coil?double helix transition preceding and promoting the formation of an ordered gel, whereas the Na + ion does not promote the coil?double helix transition, but takes part in the aggregation process probably through a phase separation mechanism.…”

Section: Introductionmentioning

confidence: 99%

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Relation between structural and release properties in a polysaccharide gel system

Mangione

Giacomazza

Cavallaro

et al. 2007

Biophysical Chemistry

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The potential utility of κ-carrageenan gels for preparing drug release devices is here shown. Structural properties of κ-carrageenan gels prepared with different salt composition and containing Ketoprofen sodium salt, as model drug, have been evaluated with static light scattering and rheological measurements. These properties have been correlated with release profiles in vitro at pH 5.5. Release properties from gelled matrices have been compared with those obtained by two commercial products containing the same drug. Results show that: i) in this system it is possible to easily control the gel texture by using different cationic concentration; ii) the kinetics of drug release by κ-carrageenan gels are dependent on the structural properties of matrices; iii) in the typical interval time used in classical local applications, all gel samples release the loaded drug almost completely, at difference with the commercial products. All these findings can provide useful suggestions for the realization of classical topical release systems.

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Section: Discussionmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relation between structural and release properties in a polysaccharide gel system

Mangione

Giacomazza

Cavallaro

et al. 2007

Biophysical Chemistry

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“…The gelation process of k-carrageenan has been widely studied. [9][10][11] The process upon cooling is commonly modeled as the transition of k-carrageenan chains from a random coil to a helix conformation. This transition is followed by the aggregation of helices to form a network.…”

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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Phase transitions of κ‐carrageenan gels in various types of salts

Kara

Arda

Kavzak

et al. 2006

J of Applied Polymer Sci

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Sol-gel and gel-sol phase transitions of k-carrageenan in various types of salts were studied using photon transmission technique. Here, LiCl, NaCl, KCl, MgCl 2 , CaCl 2 , and SrCl 2 were chosen as the proper salts for the k-carrageenan-water system. Photon transmission intensity, I tr was monitored against temperature to determine the sol-gel and gel-sol temperatures (T sg and T gs ) and activation energies (DE sg and DE gs ). It was observed that T gs temperatures were notably higher than T sg due to the hysteresis on the phase transition loops. It was observed that stronger carrageenan gels are formed in the presence of KCl compared to the others.

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Thermoreversible gelation of κ-Carrageenan: relation between conformational transition and aggregation

Cited by 141 publications

References 23 publications

Relation between structural and release properties in a polysaccharide gel system

Relation between structural and release properties in a polysaccharide gel system

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

Phase transitions of κ‐carrageenan gels in various types of salts

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