Texture properties of high and low acyl mixed gellan gels

Mao, Rui; Tang, Juming; Swanson, Barry G.

doi:10.1016/s0144-8617(99)00108-3

Cited by 103 publications

(69 citation statements)

References 13 publications

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“…Gellan gum is an extracellular anionic heteropolysaccharide consisting of a linear structure of repeating tetrasaccharide units of glucose, glucuronic acid, and rhamnose in a molar ratio of 2:1:1. It has a characteristic temperature and ionic-dependent gelling property (11). The mechanism of gelation involves the formation of double helical junction zones followed by aggregation of double helical segments to form a threedimensional network by complexation with cations and hydrogen bonding with water.…”

Section: Introductionmentioning

confidence: 99%

Stomach-Specific Controlled Release Gellan Beads of Acid-Soluble Drug Prepared by Ionotropic Gelation Method

2010

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Abstract. The purpose of the present work was the development and evaluation of stomach-specific controlled release mucoadhesive drug delivery system prepared by ionotropic gelation of gellan beads, containing acid-soluble drug amoxicillin trihydrate, using 3 2 factorial design with concentration of gellan gum and quantity of drug as variables. The study showed that beads prepared in alkaline cross-linking medium have higher entrapment efficiency than the acidic cross-linking medium. The entrapment efficiency was in the range of 32% to 46% w/w in acidic medium, which increased up to 60% to 90% w/w in alkaline medium. Batches with lowest, medium, and highest drug entrapment were subjected to chitosan coating to form a polyelectrolyte complex film. As polymer concentration increases, entrapment efficiency and particle size increases. Scanning electron microscopy revealed spherical but rough surface due to leaching of drug in acidic cross-linking solution, dense spherical structure in alkaline cross-linking solution, and rough surface of chitosan-coated beads with minor wrinkles. The in vitro drug release up to 7 h in a controlled manner following the Peppas model (r=0.9998). In vitro and in vivo mucoadhesivity study showed that beads have good mucoadhesivity and more than 85% beads remained adhered to stomach mucosa of albino rat even after 7 h. In vitro growth inhibition study showed complete eradication of Helicobacter pylori. These results indicate that stomach-specific controlled release mucoadhesive system of amoxicillin gellan beads may be useful in H. pylori treatment.

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Section: Introductionmentioning

confidence: 99%

Stomach-Specific Controlled Release Gellan Beads of Acid-Soluble Drug Prepared by Ionotropic Gelation Method

2010

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“…10 Agar and k-carrageenan co-hydrogels were studied at various mixing ratios and it was seen that the gelling temperature decreased, along with forming more deformable but weaker hydrogels.…”

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confidence: 99%

An ultra melt-resistant hydrogel from food grade carbohydrates

et al. 2017

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We report a binary hydrogel system made from two food grade biopolymers, agar and methylcellulose (agar-MC), which does not require addition of salt for gelation to occur and has very unusual rheological and thermal properties. It is found that the storage modulus of the agar-MC hydrogel far exceeds those of hydrogels from the individual components. In addition, the agar-MC hydrogel has enhanced mechanical properties over the temperature range 25-85 C and a maximum storage modulus at 55 C when the concentration of methylcellulose was 0.75% w/v or higher. This is explained by a sol-gel phase transition of the methylcellulose upon heating as supported by differential scanning calorimetry (DSC) measurements. Above the melting point of agar, the storage modulus of agar-MC hydrogel decreases but is still an elastic hydrogel with mechanical properties dominated by the MC gelation. By varying the mixing ratio of the two polymers, agar and MC, it was possible to engineer a food grade hydrogel of controlled mechanical properties and thermal response. SEM imaging of flash-frozen and freeze-dried samples revealed that the agar-MC hydrogel contains two different types of heterogeneous regions of distinct microstructures. The latter was also tested for its stability towards heat treatment which showed that upon heating to temperatures above 120 C its structure was retained without melting. The produced highly thermally stable hydrogel shows melt resistance which may find application in high temperature food processing and materials templating.

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“…10,11 Gellan gum is a polysaccharide that forms thermoreversible gels, being noncytotoxic in different tested situations. [12][13][14] It is commonly applied in the food industry, 15 and has been previously used in the biomedical field for drug delivery. 16 Gellan gum has been originally proposed by our group 17 as a new biomaterial for cartilage tissue engineering applications, yet recent studies can be found on the same application 18 and on the general use of gellan gum for tissue engineering.…”

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confidence: 99%

Injectable gellan gum hydrogels with autologous cells for the treatment of rabbit articular cartilage defects

Oliveira

Gardel

Rada

et al. 2010

Journal Orthopaedic Research

127

104

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In this work, the ability of gellan gum hydrogels coupled with autologous cells to regenerate rabbit full-thickness articular cartilage defects was tested. Five study groups were defined: (a) gellan gum with encapsulated chondrogenic predifferentiated rabbit adipose stem cells (ASC þ GF); (b) gellan gum with encapsulated nonchondrogenic predifferentiated rabbit adipose stem cells (ASC); (c) gellan gum with encapsulated rabbit articular chondrocytes (AC) (standard control); (d) gellan gum alone (control); (e) empty defect (control). Fullthickness articular cartilage defects were created and the gellan gum constructs were injected and left for 8 weeks. The macroscopic aspect of the explants showed a progressive increase of similarity with the lateral native cartilage, stable integration at the defect site, more pronouncedly in the cell-loaded constructs. Tissue scoring showed that ASC þ GF exhibited the best results regarding tissue quality progression. Alcian blue retrieved similar results with a better outcome for the cell-loaded constructs. Regarding real-time PCR analyses, ASC þ GF had the best progression with an upregulation of collagen type II and aggrecan, and a downregulation of collagen type I. Gellan gum hydrogels combined with autologous cells constitute a promising approach for the treatment of articular cartilage defects, and adipose derived cells may constitute a valid alternative to currently used articular chondrocytes. ß

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Texture properties of high and low acyl mixed gellan gels

Cited by 103 publications

References 13 publications

Stomach-Specific Controlled Release Gellan Beads of Acid-Soluble Drug Prepared by Ionotropic Gelation Method

Stomach-Specific Controlled Release Gellan Beads of Acid-Soluble Drug Prepared by Ionotropic Gelation Method

An ultra melt-resistant hydrogel from food grade carbohydrates

Injectable gellan gum hydrogels with autologous cells for the treatment of rabbit articular cartilage defects

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