An ICT-PET dual-controlled strategy for improving molecular probe sensitivity: Application to photoactivatable fluorescence imaging and H2S detection

The organic small molecule fluorescent probes are very effective tool for accurately analyzing target molecules and super-resolution microscopy biological imaging. Generally, reducing the interference of background fluorescence is one of the effective strategies to improve the resolution and signal-to-noise ratio of biological imaging. Herein, in this work, using the synergistic effect of the ICT-PET dual quenching mechanism to reduce background fluorescence, the fluorescent probe Np-N3 with naphthalimide and small size azide as photocage and the recognition site of H2S was designed and synthesized. The synergistic mechanism of ICT-PET was computationally demonstrated by TD-DFT. The Np-N3 showed low background fluorescence, high sensitivity and high selectivity for visible light and H2S, respectively. Meanwhile, under visible light irradiation (465 nm), the azide was easily reduced to amino in situ without complicated separation steps, restoring strong emission in a short time (<3 min). Importantly, the spatiotemporal-controlled imaging of live HeLa cells was successfully achieved. In addition, the probe was also applied to detect and image H2S in solution and living HeLa cells.