Main Characteristics of Cross-Linked Hydrogels

HA is related, swell more than hydrogels with hydrophobic groups the latter do not increase in volume in the presence of water [6], The swelling hydrogel very often may depend on pH, temperatnre or other factors [7], 

In designing cellular tissue, the diffusion rate of the solubilized compound is important in order to determine the rate of release of drugs or transport of nutrients and metabolites. The diffusion of nutrients, metabolites and other solubilized compounds depends on many factors, including the morphology of the network, the chemical composition of the hydrogel, the water content, the concentration of solubiUzed compounds and the level of the material swelling [7]. 

The nature of the cross-links affects the formation of the hydrogel, its shape, size and degradation. The formation of cross-links should be monitored for the biomedical applications of hydrogels. In this section, three different types of cross-linking in hydrogels are described covalent, ionic and physical interactions [10]. 

After the cross-linking process is started, it cannot be cancelled or stopped it is controlled only by the initial process conditions. Photopolymerization is the conversion of a liquid polymer solution to gel under the action of photosensitizing additives and light [10] and is the most ideal method for synthesis of cross-linked hydrogels intended for use in medical practice since it allows for the reaction to be carried out with almost 100% efficiency. 

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