How to make a hydrogel
Water, clay and living cells may soon revolutionize the field of tissue engineering
how to make a hydrogel: mix a bit of clay with water and small amounts of organic compounds. The result is a transparent mass which is strong, flexible and can be moulded into any shape, however complex. In case of damage, the material can heal itself by getting back into its original shape.
Hydrogels are used to make contact lenses, diapers, sanitary napkins, tissue engineering and in breast implants. Researchers from Japan and Korea report in the January 21 issue of Nature that a new hydrogel could be the environmentally friendly alternative to petroleum-dependent plastics that are currently available in the market.
The hydrogel can be prepared within three minutes by adding a small amount of G3-binder, an organic compound, to an aqueous solution of clay nanosheets which was pretreated with sodium polyacrylate.
These organic substances ensured that the clay nanosheets are dispersed homogeneously in the hydrogel. Unlike other supramolecular hydrogels, this material retained its shape even when immersed in an organic solvent. Though the water was replaced by the organic solvent, the gel maintained its form and integrity.
“Our hydrogel contradicts the preconception that materials held together by supramolecular forces and mostly composed of water are weak,” the researchers write in the journal.
(pictured) Hydrogels are hydrophilic polymer networks that are able to swell and retain large amounts of water and maintain their three-dimensional structures. The term Hydrogel is used at the same time for the dry substance and for the water charged gel. These polymers do not dissolve in water; upon swelling, they increase in volume, but keep their shape without breaking up. Hydrogels could be divided into Super Absorbent Polymer (SAPs) and Super Porous Hydrogels (SPHs). In general, the amount of water absorbed by the hydrogel is at least 20% of its total weight,, but SAPs are able to absorb large amount of liquid, up to 200%. The Super Porous Hydrogel, instead, is a 3-dimensional network of polymer that absorbs a large amount of water (up to 400%) in a very short period of time, due to the presence of interconnected microscopic pores. Responsive hydrogels can reversibly change volume in response to slight changes in the properties of the medium including pH, temperature, electric field, ionic strength, salt type, solvent, external stress, or light. Responsive hydrogels found many different applications because of their interesting properties: as a super absorbent material in diaper, as insulator construction materials, as water retention material in agricultural applications, in showing to obtain the artificial snow, in cosmetic and pharmaceutics industry, in artificial organs and tissue engineering, in wound dressings and in fire protection. Most hydrogels are highly bio compatible and have extremely low toxicity to the human body, eg, hydrogel products such as contact lenses and surgical dressings are being used successfully.
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