Digital Photoinduced Topographical Microsculpting of Hydrogels

Hydrogels are soft materials widely used as a substrate or matrix for cell culture to mimic the physicochemical, structural, and mechanical properties of the cell's native microenvironment. Recently, a growing body of evidence has shown that substrate topography is a key determinant of cell behavior. These studies, however, mostly rely on the use of hard elastomeric materials, particularly as introducing topography in soft hydrogels is technically challenging, labor intensive, and often does not provide a flexible design space. Here, a new approach is presented that allows robust creation of topographies on hydrogels using a maskless and contactless UV-sculpting approach. The sculpted topographies are highly programmable: the features can be designed using any digital drawing software, while the dimensions and resolution can be easily tuned via UV exposure dose or photoinitiator concentration. Microscale topographies (2–100 µm in size) can be created on a wide range of hydrogels with diverse chemical characters and mechanical properties (e.g., stiffness). As a proof of concept, this work shows that adherent cells on softer hydrogels align better to topographical cues than on stiffer hydrogels, underlining the importance of studying cell behavior in physiologically more relevant multi-cue environments.