Fig.1 1H NMR spectra of the polymer a. BLG-NCA, CDCl3-d; b. PBLG, TFA-d; c. PLG, D2O; d. PLG-g-TA, D2O; e. PLG-g-TA/RGD, D2O. a—k are the peaks corresponding to the positions in Scheme 2.

Fig.2 Gel-forming photographs of PLG-g-TA(A) and PLG-g-TA/RGD(B) polymer solution after enzyme-catalyzed reaction

Fig.3 Gelation time of PLG-g-TA/RGD polymers solution(HRP concentration was fixed at 3.2 Unit/mL as the polymer concentration changes, and the molar ratio of H2O2 to TA was fixed 0.4)(A), PLG-g-TA polymers solution(as the polymer concentration changes, the HRP concentration was fixed at 3.2 Unit/mL, and the molar ratio of H2O2 to TA was fixed at 0.4)(B) and rheological diagram of PLG-g-TA/RGD and PLG-g-TA hydrogels(the final concentration of the polymer was 40.0 g/L, the HRP concentration was fixed at 3.2 Unit/mL, and the molar ratio of H2O2 to TA was fixed at 0.4)(C)

Fig.4 P1 generation of rabbit hyaline chondrocytes

Fig.5 Cell compatibility of the co-culture of the hydrogel leaching solution and L929 cells for 48 h(n=3)(A), proliferation of hyaline chondrocytes cells in hydrogel(n=3)(B) * P<0.05; ** P<0.01; *** P<0.001.

Fig.6 Adhesion behavior of cells on the surface of PLG-g-TA hydrogel(A) and adhesion behavior of cells on the PLG-g-TA/RGD hydrogel(B)

Fig.7 Staining of chondrocytes cultured in hydrogels for 7 d Live cells were stained green by Calcein-AM, dead cells were dyed red by PI. (A) Chondrocytes survived inside the PLG-g-TA/RGD hydrogel; (B) chondrocytes survived within the PLG-g-TA hydrogel.