Fig. 4.

Representative case of ionic hydrogels in bone tissue regeneration. A) The preparation process of the gradient bimetallic ion-based hydrogels and the operation diagram. B) Schematic diagram of the gradient ionic hydrogels for synchronous regeneration in the tendon-to-bone insertion. C) H&E staining and toluidine blue staining of different experimental groups (Suture, s-Gelatin, s-Cu/Zn-Gelatin.) at four weeks and eight weeks. Used with permission [44]. Copyright 2021, AAAS. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)