Figure 4.

Representative images and quantification of void fraction in samples printed with GelMA:gelatin microgel inks after UV crosslinking and sacrificial gelatin removal. (a) Microgels are shown in black, and voids (which are filled with 2,000-kDa FITC-dextran) are shown in green. (b) Quantified void fraction for inks of varying GelMA:gelatin microgel ratios; mean ± standard deviation, n = 6. 3D printed structures demonstrating the versatility of GelMA:gelatin microgel inks. (c) A chessboard pattern was printed from two different microgel composite inks (100:0 and 40:60, visualized with red and green fluorescent microparticles, respectively). (d) After UV-crosslinking and melting of sacrificial gelatin microgels, regions of patterned void structure were observed by diffusing rhodamine B (red) into the GelMA microgels. (e) An embedded cylindrical channel was printed with two different microgel composite inks (100:0 and 0:100, visualized with red and blue fluorescent microparticles, respectively). Cross-sectional images of the embedded channel (f) pre-melt and (g) post-melt. Scale bars are 500 μm in a, 10 mm in c, 1 mm in d, and 5 mm in e-g. Statistical significance tested by one-way ANOVA with Tukey’s post-hoc analysis; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.