A Highly Sensitive Photoactive Probe for Time-Controllable Imaging of the Endoplasmic Reticulum

Light-activated probes have strong spatial and temporal control, allowing for the external control of intracellular reactions. However, the low sensitivity of traditional photoactivation probes requires a period of time to obtain fluorescence feedback after photoactivation, making it difficult to achieve real-time monitoring and time-controlled imaging. Herein, we have designed a new class of photocontrollable molecules that utilize ultraviolet (UV) light to promote rhodamine ring opening and activate fluorescence. By this mechanism, multiple probes were synthesized, and the most suitable SWJT-26 was obtained through gradual screening. It exhibits the fastest photoactivation feedback (<20 s), high selectivity, good biocompatibility, and endoplasmic reticulum targeting. In biological imaging, SWJT-26 rapidly fluoresces upon UV light, and this phenomenon is also observed in live imaging. This study has achieved the time-controlled imaging of photoactive probes, which will drive the development of photocontrolled reactions.