Fig. 2.

Characterization of GelMA composite hydrogels. (a) Scheme of the synthesis process. b Representative SEM image of the freeze-dried GelMA and CuNA-bFGF@GelMA. c Swelling kinetic curves of cross-linked GelMA at 37 °C in PBS (pH = 7.4). d Biodegradation property (in PBS + 1U/mL Collagenase solution) of different GelMAs for different time intervals at 37 °C. e The loading of bFGF on CuNA. f The release profile of bFGF from CuNA-bFGF and CuNA-bFGF@GelMA. g The release profile of copper from CuNA and CuNA-bFGF@GelMA. Data are expressed as mean ± SD (n = 3)