Multi-action of a Fluorophore in the Sight of Light: Release of NO, Emergence of FONs, and Organelle Switching

Abstract

Light, as an external stimulus, has begun to engage a phenomenal role in the diverse field of science. Encouraged by recent progress from biology to materials chemistry, various light-responsive fluorescent probes have been developed. Herein, we present a 1,8-naphthalimide-based probe NIT-NO 2 capable of releasing nitric oxide (NO) along with the formation of fluorescent organic nanoparticles (FONs) upon exposure to near-visible UV light. By synthesizing the photoproduct NIT-OH, we unveiled that initially NIT-NO 2 released NO and converted to NIT-OH, while prolonged irradiation led to the formation of FONs that is corroborated by the red-edge excitation shift as well as microscopic investigation. Finally, we have successfully applied NIT-NO 2 and NIT-OH for specific labeling of lipid droplets and plasma membranes, respectively, and demonstrated the switching from lipid droplets to plasma membranes by using light as a stimulus. These two probes show unique imaging applications inside the cells depending on the polarity and hydrophobicity of the environment. This work paves a fascinating way for the generation of excitation-dependent FONs from a small organic fluorophore and highlights its potency as an exclusive imaging tool.

Improved lipophilic probe for visualizing lipid droplets in erastin-induced ferroptosis

“…The accumulation of lipid per-oxides also alters the viscosity of LDs, and various fluorophores have been utilized to visualize this viscosity-dependent process. [8][9][10][11][12] The design strategy often involves a donor-π-acceptor architecture, which results in polarity-dependent solvatochromic emission. The presence of rotatable bonds further enhances the emission in higher viscosity media, owing to the restricted rotation and reduced non-radiative processes, making them ideal for investigating multiple targeted cellular processes.…”