Thermally Switchable Photoactivity in Azobenzene-Functionalized DNA Condensates

Soft materials capable of responding to diverse environmental stimuli are fundamental to advancing soft robotics and intelligent biomedical devices, enabling adaptive, life-like functions. Here, multimodal photothermal adaptability is reported in azobenzene-conjugated DNA condensates assembled via liquid-liquid phase separation (LLPS). These coacervates exhibit a striking temperature-dependent inversion of their photo-response: at elevated temperatures, the liquid-like droplets deform under visible light and dissolve under ultraviolet (UV) light, whereas at lower temperatures, the gel-like condensates are reshaped by UV light while remaining inert to visible light. This unique bidirectional control is attributed to the synergy of confined azobenzene photochemistry within DNA duplexes and a pronounced isomer-dependent shift in the system's glass transition and melting temperatures. This platform of multi-responsive photofluids opens new avenues for applications demanding exquisite spatiotemporal control.