Hydrogel and preparation method thereof

The invention provides a hydrogel. The hydrogel is prepared from the following components: medicine-loading particles, modified chitosan with a structure shown in a formula II, a poly-gamma-glutamic acid star-type block copolymer containing blocks with structures shown in a formula III and a formula IV, a poly-L-lysine star-type block copolymer containing blocks with structures shown in a formula V and a formula VI, and a solvent, wherein the medicine-loading particles are prepared from modified glucan with a structure shown in a formula I and medicines. The hydrogel provided by the invention is a hydrogel based on electrostatic action and Schiff base bond crosslinking; by virtue of the combination of physical electrostatic action and Schiff base bond chemical crosslinking, the hydrogel provided by the invention has relatively high strength and good stability, and ensures that the requirements of clinical injection can be met; and moreover, the medicine-loading particles are taken as a chemical crosslinking agent so as to ensure that medicines in the hydrogel can be released slowly, the targeted release and enrichment of the medicines at focus locations can be achieved, and thus the treatment effects of the medicines can be improved. The invention also provides a preparation method of the hydrogel.