Let There be Light! Light as an Engine and Regulator in Synthetic Cells.

Synthetic cells, assembled from defined molecular components, are designed to mimic the features, form, and function of living cells. Light has emerged as a uniquely precise, biorthogonal, and non-invasive stimulus for regulating and energizing these systems, enabling chemical inhomogeneity and an out-of-equilibrium state central to many cellular processes. This review highlights the biological behaviors and functions that light has helped recreate in synthetic cells, including compartmentalization, energy supply and metabolism, protein synthesis, communication, growth, shape change and division, and motility. We survey the breadth of light-responsive components incorporated into synthetic cells, spanning photoswitchable and photocleavable small molecules, photoswitchable proteins, photocatalysts, nanoparticles, and photosynthetic organelles or organisms. Finally, we offer a perspective on key design considerations such as wavelength, reversibility, integration, biocompatibility, multicolor regulation, and biohybrid strategies. Together, these advances chart promising routes toward more dynamic, energy-autonomous, and programmable synthetic cells that will deepen our understanding of cellular functions and enable emerging biotechnological applications.