High strength, biocompatible hydrogels with designable shapes and special hollow-formed character using chitosan and gelatin.

Hydrogels with good mechanical properties, excellent biocompatibility and designable shapes are of great importance for their biomedical applications. Herein, a series of high strength, biocompatible hydrogels have been synthesized by integrating sodium citrate into the thermally reversible chitosan/gelatin to form multiple physically crosslinking networks. Besides the ideal formability, a thermal etching or welding method has been developed to program the surface morphology and fabricate hydrogels with complicated shapes freely. More impressively, the special hollow "cup-shaped and tubular" structure has also been constructed by applying an interrupted gelation process in controlled ion crosslinking time and the subsequent dissolving process at 37°C in deionized water. The high strength, biocompatible hydrogels with special internal and external shape adjustable characters, potentially useful in vascular repair and substitutes of cartilage, may further broaden our understanding of the plasticity of the hydrogels.