Figure 1:

Schematic representation of photopolymerization process resulting in the formation of hydrogel scaffolds presenting different types of gradients. Spatial gradient of photopolymerizable macromers, RGD-PEGMA, PEGMA, Ssite and Dsite PEGDA were designed for each investigated gradient hydrogel. Syringe pumps were programmed to deliver two distinct precursor solutions into a transparent reaction chamber which was exposed to a visible light (λ = 514nm) using an argon ion laser. Hydrogel crosslinking occurred continuously with the ascending reaction front as precursor solutions were fed to the reaction vessel. The resultant scaffolds presented (1) steep and (2) shallow gradients in RGD, (3) gradients in elastic modulus, (4) gradients in protease-sensitivity, and (5) a concurrent RGD and protease-sensitivity gradient and a countercurrent or opposing modulus gradient.