Patterning micro-stiffness in cell-adhesive substrate using microfluidics-based lithography

In this study, we demonstrate the formation of 3D cell-adhesive hydrogels exhibiting well-defined spatial variation in stiffness using our previously developed microfluidics-based lithography technique. PEG monoacrylate-linked bovine fibrinogen (PEG-fibrinogen) is photopolymerized into specific, user-defined shapes inside a microchannel, and successive cycles of fabrication result in a heterogeneous structure with controlled regional variations in stiffness. Atomic force microscope (AFM) indentations were used to directly confirm the micro-stiffness distribution, and morphological and migratory behavior of cells in microenvironments of controlled variations in stiffness was characterized. Our approach allows control of microscale variations of stiffness in cell-adhesive substrates with high precision and flexibility and offers the opportunity to examine differential cell-ECM interactions relevant to a multitude of fundamental cellular processes.