Extended Data Fig. 1: Characterization of dityrosine cross-linking in hydrogels.
a. Representative PIV plots bead displacement of gelatin hydrogels (50, 100, and 150 mg/mL), collagen type I hydrogels (1, 3 and 6 mg/mL), and fibrin hydrogels (5. 10 and 20 mg/mL) on blue light exposure (3.6 J/cm2, scale bar 100 µm). b. Representative heat maps of gelatin hydrogels before (OFF) and after (ON) local exposure to blue light, far red light (670 nm) and blue light without photo-initiator (PI) (scale bar 100 µm). c. Quantification of local indentation moduli of gelatin hydrogels (150 mg/mL) before (OFF) and after (ON) on exposure to blue light (0.13 mM Ru, 20 mW/cm2 for 3 minutes, 3.6 J/cm2) by atomic force microscopy nanoindentation (spherical tip radius of 6.79 µm, n = 27 measurements from 1 representative hydrogel per condition, ****p<0.0001, two-tailed unpaired Student’s t-test with Welch’s correction). d. Representative heat maps of tyramine-functionalized hyaluronic acid (HA-Tyramine) hydrogels and methacrylated hyaluronic acid before and after local exposure to blue light (scale bar 100 µm). e. Representative time sweeps for storage (G’) and loss (G’’) modulus of HA-Tyramine hydrogels and methacrylated hyaluronic acid (meHA) hydrogels after blue light exposure. f. Quantification of storage moduli (G’) of bovine gelatin hydrogels (150 mg/mL) before (OFF) and after (ON) exposure to blue light (20 mW/cm2 blue light for 3 minutes, 3.6 J/cm2) with 0.13 mM and 0.26 mM ruthenium (Ru) (n = 9 hydrogels per group (0.13mM) and n=5 hydrogels per group (0.26mM), **P = 0.0082, ns= not significant, *P = 0.0386 between 0.13mM OFF/ON, *P = 0.0213 between 0.26mM OFF/ON by one-way ANOVA with Tukey’s multiple comparisons test). g. Quantification of storage moduli (G’) of gelatin hydrogels (porcine, 150 mg/mL): after incubation in PBS containing 0.13 mM Ru for 5, 10, 20 and 30 min prior exposure to blue light (n = 3 hydrogels per group, mean ± s.d, n.s = not significant, one-way ANOVA with Tukey’s multiple comparisons test); after incubation in PBS containing 0.13 mM Ru and 10, 20, or 40 mM SPS for 10 minutes prior to exposure to blue light (n = 3 hydrogels (10 mM) and n = 4 hydrogels (20, 40 mM), mean ± s.d, n.s = not significant, one-way ANOVA with Tukey’s multiple comparisons test); at increasing blue light dosage (0.9 - 3.6 J/cm2) (n = 3 hydrogels per group, mean ± s.d, n.s = not significant, one-way ANOVA with Tukey’s multiple comparisons test). For box plots (1C and 1F), the centre line represents the median, the box limits are upper and lower quartiles, and the whisker limits are the minimum and maximum points on the plots.
