Preparation of hydroxypropyl agars and their properties

Zhang, Xiaodong; Liu, Xin; Cao, Mingzhao; Xia, Kai; Zhang, Yuqiao

doi:10.1016/j.carbpol.2015.04.056

Cited by 18 publications

(6 citation statements)

References 14 publications

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“…In the first stage, the weight loss was due to the volatilization of free water within the carrageenan molecules, and no obvious difference was observed in the weight loss of Ca-IC compared to that of Na-IC. In the second stage, weight loss was due to the decomposition of ι-carrageenan [ 33 ], in which galactose hydroxyl groups were rapidly dehydrated and decomposed; the C-H, C-O, and C-C bonds were broken; and the main chain was interrupted. The DTG results showed that the decomposition temperatures of Na-IC and Ca-IC were 161 °C and 160 °C, respectively, which indicated no difference in the thermal stability of Na-IC and Ca-IC powders.…”

Section: Resultsmentioning

confidence: 99%

Eco-Friendly Extraction, Structure, and Gel Properties of ι-Carrageenan Extracted Using Ca(OH)2

et al. 2022

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An eco-friendly method for ι-carrageenan extraction from seaweed Eucheuma denticulatum through boiling and using a low concentration of Ca(OH)2 is reported. Compared to the traditional method of ι-carrageenan extraction using NaOH, the reported method using Ca(OH)2 had the advantages of using 93.3% less alkali and 86.8% less water, having a 25.0% shorter total extraction time, a 17.6% higher yield, and a 43.3% higher gel strength of the product. In addition, we evaluated the gel properties and structures of ι-carrageenan products extracted by Ca(OH)2 (Ca-IC) and NaOH (Na-IC). The Fourier transform infrared spectroscopy results showed that the structures of Ca-IC and Na-IC did not change remarkably. The results of the thermogravimetric analysis and differential scanning calorimetry showed that Ca-IC had the same thermal stability as Na-IC. The results of the textural analysis showed that Ca-IC had a higher hardness and better chewiness compared to Na-IC. Rheological results indicated that Ca-IC and Na-IC exhibited shear-thinning and non-Newtonian fluid properties, whereas the viscosity of Ca-IC was less than that of Na-IC. In conclusion, this new method of ι-carrageenan extraction using Ca-IC is markedly better and yields higher quality carrageenan than the conventional method of using Na-IC.

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Section: Resultsmentioning

confidence: 99%

Eco-Friendly Extraction, Structure, and Gel Properties of ι-Carrageenan Extracted Using Ca(OH)2

et al. 2022

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“…Meanwhile, the melting temperatures showed the same inclination as that of the gelling temperatures. According to the references, this may be due to the decreased intermolecular interactions due to the oxidation [ 18 ]. It was worth mentioning that further GT immobilization and reduction may lead to the slightly enhanced intermolecular interactions.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Gentamicin-Immobilized Agar with Improved Antibacterial Activity

Hou

Xie

et al. 2022

Polymers

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To develop agar derivatives with good antibacterial activity and decreased gelling and melting temperatures, two agar–gentamycin conjugates with 9.20% and 12.68% gentamicin immobilized were fabricated by oxidation, Schiff base and reduction reaction, and characterized by a Fourier Transform Infrared Spectrometer, 1H nuclear magnetic resonance and an elemental analyzer. It was found that the modifications changed the intermolecular interactions, leading to decreased gelling and melting temperatures for the oxidized agar and slightly increased gelling and melting temperatures for agar–gentamycin conjugates. Further studies of antimicrobial properties showed that the two agar–gentamycin conjugates possessed good antibacterial activity, which was positively correlated with the dosage and the immobilization rate of gentamicin. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of agar–gentamycin conjugates with higher immobilization rates of gentamicin against Escherichia coli were 39.1 μg/mL and 156.2 μg/mL, respectively, and the MICs and MBCs against Staphylococcus aureus were 19.5 μg/mL and 78.1 μg/mL, respectively. A biofilm test indicated that certain concentrations of agar–gentamycin conjugate could effectively inhibit the biofilm formation of Escherichia coli and Staphylococcus aureus. In summary, agar–gentamycin conjugates possess good antibacterial activities and may be applied as a new kind of antibacterial material.

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“…The first study was reported at the end of the 19th century [ 116 , 117 ] using epoxy derivatives as coupling agent in two-step-reactions. More recently, a single-step synthesis has been reported in order to modulate the rheological and thermal properties of agarans under milder reaction conditions [ 51 , 52 ].…”

Section: Amphiphilic Modifications Of Polysaccharidesmentioning

confidence: 99%

“…The process was simplified in 2015 and 2018 by Zhang et al who reported a one-step synthesis of amphiphilic agarose derivatives. The reaction involved epoxides (ethylene oxide, 1,2-propylene oxide, or 1,2-epoxybutane) with agarose in aqueous basic conditions [ 52 ]. For the substituted epoxides, the reactions occurred only in the presence of sodium borohydride [ 51 ].…”

Section: Amphiphilic Modifications Of Polysaccharidesmentioning

confidence: 99%

Formation of Amphiphilic Molecules from the Most Common Marine Polysaccharides, toward a Sustainable Alternative?

Wong

Brault

Gasparotto³

et al. 2021

Molecules

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Marine polysaccharides are part of the huge seaweeds resources and present many applications for several industries. In order to widen their potential as additives or bioactive compounds, some structural modifications have been studied. Among them, simple hydrophobization reactions have been developed in order to yield to grafted polysaccharides bearing acyl-, aryl-, alkyl-, and alkenyl-groups or fatty acid chains. The resulting polymers are able to present modified physicochemical and/or biological properties of interest in the current pharmaceutical, cosmetics, or food fields. This review covers the chemical structures of the main marine polysaccharides, and then focuses on their structural modifications, and especially on hydrophobization reactions mainly esterification, acylation, alkylation, amidation, or even cross-linking reaction on native hydroxyl-, amine, or carboxylic acid functions. Finally, the question of the necessary requirement for more sustainable processes around these structural modulations of marine polysaccharides is addressed, considering the development of greener technologies applied to traditional polysaccharides.

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Preparation of hydroxypropyl agars and their properties

Cited by 18 publications

References 14 publications

Eco-Friendly Extraction, Structure, and Gel Properties of ι-Carrageenan Extracted Using Ca(OH)2

Eco-Friendly Extraction, Structure, and Gel Properties of ι-Carrageenan Extracted Using Ca(OH)2

Synthesis of Gentamicin-Immobilized Agar with Improved Antibacterial Activity

Formation of Amphiphilic Molecules from the Most Common Marine Polysaccharides, toward a Sustainable Alternative?

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