Rna Buffering Fluorogenic Probe for Nucleolar Morphology Stable Imaging And Nucleolar Stress-Generating Agents Screening.

In the realm of cell research, membraneless organelles have become a subject of increasing interest. However, their ever-changing and amorphous morphological characteristics have long presented a formidable challenge when it comes to studying their structure and function. In this paper, a fluorescent probe Nu-AN is reported, which exhibits the remarkable capability to selectively bind to and visualize the nucleolus morphology, the largest membraneless organelle within the nucleus. Nu-AN demonstrates a significant enhancement in fluorescence upon its selective binding to nucleolar RNA, due to the inhibited twisted intramolecular charge-transfer (TICT) and reduced hydrogen bonding with water. What sets Nu-AN apart is its neutral charge and weak interaction with nucleolus RNA, enabling it to label the nucleolus selectively and reversibly. This not only reduces interference but also permits the replacement of photobleached probes with fresh ones outside the nucleolus, thereby preserving imaging photostability. By closely monitoring morphology-specific changes in the nucleolus with this buffering fluorogenic probe, screenings for agents are conducted that induce nucleolar stress within living cells.

Trifluoroethylamine-substituted solvatochromic fluorophores exhibit polarity-insensitive high brightness.

In this study, we have uncovered that trifluoroethylamine-substituted solvatochromic fluorophores maintain consistently high and stable fluorescence intensity in diverse polar environments, including highly polar and protic solvents. The 1,8-naphthalimide derivatives serve as a buffering fluorogenic indicator for lipid droplet morphology during the fusion process and ratiometric probe for microenvironment polarity based on Halo-tag technology.

In Situ Real-Time Nanoscale Resolution of Structural Evolution and Dynamics of Fluorescent Self-Assemblies by Super-Resolution Imaging.

The visualization of self-assembled structure and dynamics at the molecular level has become a powerful method to understand structure-function relationships of self-assembly. Herein, we in situ real-time imaged the dynamic process of benzyl-naphthalimide dyes at the nanoscale and inspected their internal structure with minimum 2.8 nm localization accuracy through single-molecule localization microscopy (SMLM) imaging. We monitored the growth process of three different assemblies in situ, which possessed highly heterogeneous dynamics with different shapes and growth rates. Furthermore, diverse growth rates were also found at different sites in the same assembly. These results highlight the application of super-resolution microscopy techniques for real-time visualization of internal assembled structure and dynamics in situ.