CXCL12 and periodontitis: Inspired by this, Ge and co‐workers reported an injectable hydrogel (PEGPD@SDF‐1) to realize tissue regeneration and periodontitis treatment in response to oral temperature and gingipain.[259] The PEGPD@SDF‐1 hydrogel contains three major parts: i) four‐arm PEGDA were served as the scaffold of hydrogel; ii) a functional peptide module was designed which has a short antimicrobial peptide (SAMP) center and two anchor peptide units in its lateral.