Photocleavable Systems for Cell Biology: Conceptual Design across Molecular Modalities

The spatiotemporal control of biomolecular functions via light-triggered bond cleavage has emerged as a powerful approach in chemical biology and cell biology. In this concept review, we classify and discuss three major modalities of photo-cleavable systems—proteins, small molecules, and metal complexes—highlighting their design principles, biological applicability, and remaining challenges. Emphasis is placed on recent efforts to address key design challenges—such as balancing functional performance, biological compatibility, and optical responsiveness—across different molecular modalities, offering perspectives for the next generation of photo-responsive tools for biological research.