Carboxylate anions hydrogels

To the best of our knowledge, only a few studies have attempted to prevent the calcification of HEMA-based hydrogels. It has been reported that introduction of carboxylate anions can either prevent or enhance calcification. Cemy et al. (21) found that copolymers of HEMA with 4 wt% methaciylic acid (MAAc) did not calcify under subcutaneous implantation in a rat for 14 months. A similar result was also observed after the implantation of HEMA/MAAc copolymers in the animal urinary tract (22). Other studies carried out in vitro showed that the presence of carboxylate anions significantly reduced the deposition of calcium phosphate (23) and calcium oxalate (24) on acrylic polymers and certain biopolymers. These findings obviously suggest an inhibitory effect of carboxylate anions on calcification. However, by contrast,... 

Superabsorbent polymers or superabsorbent polymer gels are mostly crosslinked polymers that have a high coneentration of anions such as carboxylic acid. These ionie groups are hydrated and a large amount of water is absorbed. The polymer then swells, forming a hydrogel. 

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