Leveraging Crosslinker Diffusion to Template Stiffness Gradients in Alginate Hydrogels

This study presents a method to create stiffness gradients in alginate hydrogels using a stenciling approach with calcium crosslinking, which affects both opacity and elastic modulus. By controlling the calcium concentration and gradient development time, researchers can manipulate the steepness and maximum opacity of these gradients. The opacity serves as a proxy for the local elastic modulus, allowing for the study of mechanobiology. The functionalized alginate gels with collagen and stiffness gradients facilitated spatially dependent cell invasion, with stiffer regions promoting deeper invasion of breast cancer cells. This technique offers a simple way to explore mechanosensitive cellular behaviors, such as cancer invasion and wound healing.