The behavior of swollen gellan gum hydrogels in terms of mechanical properties, weight loss, and cell growth inhibition of leachates is presented. Low-acyl gellan gum (LAGG), high-acyl gellan gum (HAGG), and a HAGG-LAGG blend were soaked in phosphate-buffered saline (PBS) at pH 7.4 and 37 C for up to 168 days. The gels exhibited their maximum mass loss and swelling after 28 days of immersion in PBS. LAGG gels exhibited lower value for mass loss and the chain-release diffusion coefficient than gels consisting of HAGG and the HAGG-LAGG blend. The change in mechanical and rheological characteristics during soaking of the three hydrogels was attributed to mass loss, while LAGG hydrogels also showed evidence of effects because of cation exchange with the surrounding medium. The mechanical characteristics of the LAGG, HAGG, and blend hydrogels relative to each other did not change during swelling (although the magnitude changed). L929 fibroblasts growth inhibition tests showed that the leachate products of the three gels can be considered noncytotoxic, which is important for their future application in tissue engineering. 53 6 2 e f , strain-at-failure; E t , tangent modulus calculated using the slope of a linear fit of the stress-strain plot at 15%-25% strain; G 0 , storage modulus; G 00 , loss modulus; c max , maximum shear strain; r f , stress-at-failure; s max , the maximum shear stress. The naming convention for the sample name is "hydrogel type-days immersed." For example, LAGG-28 indicates a LAGG hydrogel immersed for 28 days. The height of gels used in rheological and compression testing was 5 and 10 mm, respectively. ARTICLE WWW.MATERIALSVIEWS.COM WILEYONLINELIBRARY.COM/APP

Ionic‐covalent entanglement (ICE) hydrogels are a recently introduced new type of robust materials for potential future application in the fields of tissue engineering and soft robotics. Here the degradation behavior of gellan gum/polyacrylamide ICE hydrogels immersed in PBS or enzyme solutions is presented. It is demonstrated that ICE gels immersed in enzymes became stiffer, whereas under cyclic testing their mechanical responses stabilize after 10 loading/unloading cycles whether immersed in PBS or enzyme solutions. The leachates of the ICE hydrogels were found to be non‐cytotoxic for the growth of L929 and PC12 cells. These findings will be of benefit to the future development of tissue engineering applications based on these gel materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41216.