Figure 9.

(a) Fluorescently labeled arginine-glycine-aspartic acid-serine-cysteine (RGDSC, green) was swollen into cell-laden gels along with a photoinitiator and exposed to UV light through a photolithography mask, causing a radical-mediated addition of a thiol across an olefin and creating stripes of the adhesive ligand in the gel. After swelling in fresh media to remove unreacted RGDSC, fluorescently labeled proline-histidine-serine-arginine-asparagine-cysteine (PHSRNC, red) was similarly patterned in perpendicular stripes, creating an array of four unique environments in a single cell-laden gel: blank, RGD-only, PHSRN-only, and RGD plus PHSRN. Cells encapsulated within the gel are labeled orange. Scale bar = 200 μm. (b) Circle-shaped columns were degraded to remove cells from a certain environmental niche. Scale bar = 200 μm. (c) Those cells were then plated on tissue culture polystyrene and grown to show continued viability. Immunostained for F-actin (green) and cell nuclei (blue). Scale bar = 50 μm. (d) Fibroblast outgrowth is directed by degrading channels in the strain-promoted azide-alkyne cycloaddition gel and tethering RGD only in the desired path by using focused laser light only in the channel enclosed by the dotted line. Scale bar = 100 μm. Adapted with permission from Reference 56.