An Opto-Actuated Hydrogel for Cell Mechanoactuation and Real-Time Force Monitoring.

Cellular force sensing and transduction are fundamental processes in development, homeostasis, and disease. To understand how cells detect and integrate mechanical forces, we need non-invasive methods to apply forces at the molecular scale while monitoring cellular responses within physiological contexts. Here, we present a mechanoactuated hydrogel interface that can exert forces on integrin adhesion receptors and allows monitoring of traction force responses in real time. The actuation is achieved by light excitation of a rotary molecular motor presenting an adhesion peptide to bind integrins at the cell membrane and to a hydrogel surface via flexible polymer chains. Illumination results in chain twisting and an applied pulling force on the linked integrin receptors within subcellular illuminated areas. Fluorescent particles in the hydrogel allow parallel quantification of cellular forces by traction force microscopy. With this methodology, we monitored talin recruitment, actin organization, and traction force generation and their reversibility in response to applied forces by the rotary motor-interface. We demonstrate reversible talin recruitment, enhanced F-actin polymerization, and a reduction in cell traction force when force is applied to focal adhesions. This research expands the application of nano machine-based actuation within soft hydrogels and showcases its capabilities.