Self-healing gelatin-based shape memory hydrogels via quadruple hydrogen bonding and coordination crosslinking for controlled delivery of 5-fluorouracil.

Gelatin-UPy based on gelatin with ureidopyrimidinone (UPy) side chains was prepared with varying content of UPy units. On increasing the UPy content, the glass transition temperature, crystallinity and swelling decreased. Gelatin-UPy demonstrated self-healing properties as the UPy units could reversibly form dimers. At the same time, the gelatin-UPy and gelatin-UPy hydrogels demonstrated thermal responsive shape memory behaviors. The introduction of coordination crosslinking by introducing Fe3+ in gelatin-UPy hydrogels not only enhanced the crosslinking degree of gelatin-UPy and decreased the swelling degree, but also significantly improved the self-healing properties. As a drug carrier, gelatin-UPy hydrogels could achieve controlled release of 5-fluorouracil (5-FU) drug on increasing the content of UPy and concentration of Fe3+. The gelatin-UPy based materials are expected to find significant use as suppository and tissue engineering materials to treat tumors.