Injectable hydrogel as well as preparation method and application thereof

The invention discloses injectable hydrogel as well as a preparation method and application thereof. The hydrogel comprises a hyaluronic acid derivative HA-ADH modified by hydrazide groups, an aldehyde bi-functionalized hyaluronic acid derivative A-HA-Dop modified by catechol in a side chain as well as an aldehyde group terminated polyoxyethylene-polypropylene oxide-polyoxyethylene triblock copolymer A-PEO-PPO-PEO-A. On one hand, the aldehyde group terminated A-PEO-PPO-PEO-A can be self-assembled into micelle, and a first network of hydrogel can be constructed by use of the characteristic of thermosensitive sol-gel conversion; and on the other hand, aldehyde groups on the surface of the A-PEO-PPO-PEO-A micelle and aldehyde groups on the A-HA-Dop can form acylhydrazone bonds with hydrazidegroups on the HA-ADH in a physiological environment to construct second and third crosslinked networks of hydrogel. By physical acting force and reversible dynamic covalent bond acting force, the injectable multi-network cros