Peptides with good biocompatibility and biodegradability, bioactivity and self-assembly ability have received widespread attention. Self-assembly properties of peptides can provide hydrogel formation ability to polymers, and then not only controlling gel network construction but endowing polymer hydrogels with stimuli-responsibility and mechanical modulation properties. By use of peptides with special functionality, chemical crosslinked polymer hydrogels are endowed with cell-adhesive, enzyme-sensitive and antibacterial biofunctionalities. In addition, introducing network construct and structural control properties as well as functionalities of peptide into physical/chemical double crosslinked hydrogels simultaneously can not only turn a hydrogel into functional materials but also enhance the chemical crosslinked network through peptide self-assembly. In this review, we summarize the current achievements in the study of peptide self-assembled polymer hydrogels, peptide-functionalized chemical crosslinked polymer hydrogels and physical/chemical double crosslinked polymer hydrogels based on peptide. Finally, development prospects of such hydrogels are briefly predicted.

Contents
1 Introduction
2 Physical cross-linked hydrogels
2.1 Hydrogels based on coiled coil assembly
2.2 Hydrogels based on β-sheet assembly
2.3 Hydrogels based on triple helix assembly
3 Chemical cross-linked hydrogels
3.1 Cell-adhesive
3.2 Enzyme-degradation
3.3 Antibacterial property
3.4 Tissue-adhesive
4 Physical/chemical double cross-linked hydrogels
5 Conclusion