Kinetic and equilibrium processes in the formation and melting of agarose gels

Mohammed, Z.H.; Hember, M.W.N.; Richardson, Robert K.; Morris, Edwin R.

doi:10.1016/s0144-8617(98)00011-3

Cited by 99 publications

(68 citation statements)

References 22 publications

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“…These findings are in good agreement with previous reports on thermoreversible gels. Agarose gels also showed higher thermal stability when the gels were formed at lower cooling rates (Mohammed et al, 1998). Moritaka, Takahashi, and Kubota (2007) also reported that storage modulus of gels of K-type gellan, agar, and kappa-carrageenan increased when the cooling rate of the solution was decreased.…”

Section: Resultsmentioning

confidence: 97%

“…They interpreted this by structural observation that during the holding period the un-gelled solutions resolved progressively into regions of high and low polymer concentration, and that the resulting heterogeneity gave weaker networks when the solutions were gelled by cooling. On the other hand, Mohammed, Hember, Richardson, and Morris (1998) reported that agarose gels showed larger elastic modulus and were more thermally stabilized by cooling more slowly.…”

Section: Introductionmentioning

confidence: 99%

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The effect of thermal history on the elasticity of K-type gellan gels

Nitta

Yoshimura

Nishinari

2014

Carbohydrate Polymers

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

The effect of thermal history on the elasticity of K-type gellan gels

Nitta

Yoshimura

Nishinari

2014

Carbohydrate Polymers

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“…The polymer forms strong gelling ability [10] [66] [67] and is used in the separation, purification, and characterization of biomacromolecules in such techniques as gel filtration, affinity chromatography [68], hydrophobic chromatography [69] and electrophoresis. The polymer is currently attempted to use in pharmaceutical [1], drug delivery and tissue engineering [3] as a gelling agent.…”

Section: Gelation Mechanism Of Agarose (Agar)mentioning

confidence: 99%

The Principle of Polysaccharide Gels

Tako¹

2015

ABB

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For several decades attention has been directed to natural polysaccharide gels and synthesized polymer gels. The structure-function relationships at molecular level in water of polysaccharides, κ-carrageenan, ι-carrageenan, agarose (agar), and gellan family of polysaccharides (gellan, welan, rhamsan, S-657, deacetylated rhamsan and native gellan gum), which are industrially useful polysaccharides extracted from family of red seaweeds and bacteria, in principle are discussed on the view point of rheological aspects. The polysaccharide molecules (0.1% -1.0%) play a dominant role in the center of the tetrahedral cavities occupied by water molecules (99.0% -99.9%), and the arrangement is similar to a tetrahedral structure in a gelation process. The cage and hydrophobic effect play thermal dynamically dominant role in gelation process which gives lowest entropy to electrons of sugar residues. Though the chemical structure of these polysaccharides similar each other, their rheological (gelling) characteristics are quite different. Many investigations about the gelling properties of the polysaccharides have been undertaken to elucidate the structure-function relationship, but no other researchers have established mechanism at the molecular level. There is consistency in our investigations. Thus, the rheological analysis is one of significant methods for understanding the structure-function relationship of polysaccharides in aqueous media. The discussion provides many important information not only in academic field, but also in industrial one, such as food, cosmetic, pharmaceutical, drug delivery and tissue industries, and biotechnology.

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“…One typical example is agarose gel, in which the aggregation of double helices leads to a thermal hysteresis of several tens of degrees between gelation and the subsequent melting. [55][56][57] Thereby, it is proper to say that no pronounced aggregation of triple helices exists in SPG-sorbitol aqueous gel, and the gel property is from a three-dimensional network constituted by the extremely entangled triple helix I of SPG. This is different from the Rhizobium capsular polysaccharide gel, where gel properties are caused by the further aggregations of rigid chains after the conformational transition.…”

Section: Gelation Mechanism Of Spg-sorbitol Aqueous Solutionmentioning

confidence: 99%

Gelation behaviors of schizophyllan‐sorbitol aqueous solutions

Fang

Nishinari

2003

Biopolymers

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On addition of D-sorbitol, schizophyllan (SPG) aqueous solution forms a thermoreversible gel upon cooling. The gelation process is characterized by rheology, differential scanning calorimetry (DSC), and optical rotation measurement (ORD). It is found that the Winter-Chambon criterion works well in determining the critical gelation point of the present system, although the criterion has been scarcely applicable to systems that show weak-gel properties even before gelation. Moreover, ORD and DSC results indicate that a disordered to ordered conformational change accompanies the gelation process, which is attributed to the transition from SPG triple helix II to I. The gelation temperature of SPG-sorbitol aqueous solution is almost independent of SPG concentration in the examined concentration range and is slightly decreased by lowering SPG molecular weight, while greatly influenced by sorbitol content. The gelation is considered to be induced by the transition from SPG triple helix II to I, which leads to a three-dimensional network constituted by the extremely entangled and stiff SPG triple helices I. Furthermore, it is proved that neither junction zone nor aggregation of SPG triple helices is involved in the SPG-sorbitol gels. The SPG-sorbitol gel is structurally like a solution that is unable to flow within a timescale of usual observation.

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Kinetic and equilibrium processes in the formation and melting of agarose gels

Cited by 99 publications

References 22 publications

The effect of thermal history on the elasticity of K-type gellan gels

The effect of thermal history on the elasticity of K-type gellan gels

The Principle of Polysaccharide Gels

Gelation behaviors of schizophyllan‐sorbitol aqueous solutions

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