RESUMEN

Cyclodextrins, cyclic oligosaccharides with a hydrophobic cavity that form inclusion complexes with nonpolar molecules, can be used to functionalize other polysaccharides. Xanthan gum, locust bean gum or chitosan can be crosslinked using citric acid in the presence of ß-cyclodextrin to produce insoluble matrices. In this work, polymeric foams based on those polysaccharides and saponin have been prepared using a green synthesis method to increase the porosity of the matrices. The saponin of soapbark (Quillaja saponaria) has been used to obtain foams using different procedures. The influence of the synthesis path on the porosity of the materials and their corresponding sorption capacities in the aqueous phase were evaluated.

RESUMEN

Locust bean gum (LBG), a vegetable galactomannan extracted from carob tree seeds, is extensively used in the food industry as a thickening agent (E410). Its molecular conformation in aqueous solutions determines its solubility and rheological performance. LBG is an interesting polysaccharide also because of its synergistic behavior with other biopolymers (xanthan gum, carrageenan, etc.). In addition, this hydrocolloid is easily modified by derivatization or crosslinking. These LBG-related products, besides their applications in the food industry, can be used as encapsulation and drug delivery devices, packaging materials, batteries, and catalyst supports, among other biopharmaceutical and industrial uses. As the new derivatized or crosslinked polymers based on LBG are mainly biodegradable and non-toxic, the use of this polysaccharide (by itself or combined with other biopolymers) will contribute to generating greener products, considering the origin of raw materials used, the modification procedures selected and the final destination of the products.

Asunto(s)

RESUMEN

Polysaccharides such as xanthan, locust bean gum or chitosan are easily crosslinked and purified using citric acid in an ecofriendly process. In order to achieve an improved sorption capability towards hydrophobic solutes, ß-cyclodextrin, a cyclic oligosaccharide, and lignin, a natural aromatic polymer, are incorporated in the same process. Once crosslinked, the influence of these on the sorption capacities towards model solutes has been assessed by comparing the sorption isotherms of matrices with or without the hydrophobic modifications. The sorption capacities of these materials for different phenolic compounds have also been tested to ascertain their efficiencies as a function of their affinities to ß-cyclodextrin cavities and/or their partition coefficients. In addition, these functionalized carbohydrate matrices were successfully characterized by principal component analysis, which is a useful tool to select the most appropriate polymers to interact with a specific molecule.

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RESUMEN

Cyclodextrins are glucose macrocycles whose inclusional capabilities towards non-polar solutes can be modulated with the help of other macrostructures. The incorporation of cyclodextrin moieties into larger structures produces five types of new materials: crosslinked networks, functionalized chains, amphiphilic cyclodextrins, polyrotaxanes and nanocomposites. This review presents crosslinking and grafting to prepare covalently-attached cyclodextrins, and applications in the food and pharmaceutical sectors, from an historical point of view. In food science, applications include debittering of juices, retention of aromas and release of preservatives from packaging. In biomedical science, cyclodextrin polymers are applied classically to drug release, and more recently to gene delivery and regenerative medicine. The remarkable points are: 1) epichlorohydrin and diisocyanates have been extensively used as crosslinkers since the 1960s, but during the last two decades more complex cyclodextrin polymeric structures have been designed. 2) The evolution of cyclodextrin polymers matches that of macromolecular materials with regard to complexity, functionality and capabilities. 3) The use of cyclodextrin polymers as sorbents in the food sector came first, but smart packaging is now an active challenge. Cyclodextrins have also been recently used to design treatments against the coronavirus disease 2019 (COVID-19).

RESUMEN

Three different polysaccharides, xanthan gum, chitosan and locust bean gum, were crosslinked with or without ß-cyclodextrin, using citric acid in different ratios, to create 'green' hydrogel matrices. The crosslinking of these polysaccharides was produced through an inexpensive and innocuous solvent-free synthesis process. A favorable swelling behavior of the hydrophilic matrices facilitates the sorption of the solutes tested. Interestingly, the amount of ß-cyclodextrin groups is not the only factor to yield the best sorption capability for hydrophobic model molecules: polysaccharides themselves also influence the sorption depending on their characteristic functional groups, the conformation of their chains and, as mentioned above, their degrees of swelling. In order to ascertain the effect of the polysaccharides on the sorption capabilities of a model sorbate (1-naphthol), isotherms using a wide range of solute concentrations were analyzed, and the Hill equation yielded the best fitting results and provided some insight into the mechanisms of interaction.

Asunto(s)

RESUMEN

The incorporation of cyclodextrins into polymeric crosslinked gels of hydrophilic nature can be useful for promoting the sorption of hydrophobic molecules and/or modulating the release of active principles. The covalent addition of these excipients to the matrix integrates their solubilizing effect that can contribute to increase the capacity of retention of hydrophobic substances. In this study, three diverse polysaccharides, chitosan, xanthan gum, and locust bean gum, were crosslinked with or without ß-cyclodextrin, using citric acid in different ratios, to create hydrogel matrices. Through a green synthetic path, the efficient production of soluble and insoluble (hydrogel) networks functionalized with ß-cyclodextrin was achieved by means of a solventless procedure. The characterization of their chemical composition, swelling in water, and their sorption and release behavior were also carried out in this work.