Light-induced assembly and repeatable actuation in Ca2+-driven chemomechanical protein networks

Abstract Programming rapid, repeatable motions in soft materials has remained a challenge in active matter and biomimetic design. Here, we present a light-controlled chemomechanical network based on Tetrahymena thermophila calcium-binding protein 2 (Tcb2), a Ca2+-sensitive contractile protein. These networks—driven by Ca2+-triggered structural rearrangements—exhibit dynamic selfassembly, spatiotemporal growth, and contraction rates comparable to actomyosin systems. By coupling light-sensitive chelators for optically triggered Ca2+ release, we achieve precise growth and repeatable mechanical contractility of Tcb2 networks, revealing emergent phenomena such as boundary-localized active regions and density gradient-driven reversals in motion. A coupled reaction-diffusion and elastic model explains these dynamics, highlighting the interplay between chemical network assembly and mechanical response. We further demonstrate active transport of particles via network-mediated forces in vitro and implement reinforcement learning to program seconds-scale spatiotemporal actuation in silico. These results establish a platform for designing responsive active materials with rapid chemomechanical dynamics and tunable optical control, with applications in synthetic cells, sub-cellular force generation, and programmable biomaterials. Competing Interest Statement The authors have declared no competing interest. Footnotes We added 2 new figures (split Figs. 5 and 6 and added Fig. 7) to the main text, 7 new figures to the Supplementary Information (Figs. 7, 8 ,9, 10, 15, 16, 29) and 2 new videos (Part 2 Section VI and Part 3 Section VII) to the Supplementary Videos .