Exploiting directed self-assembly and disassembly for off-to-on fluorescence responsive live cell imaging.

Area of Science:

• Nanotechnology
• Biomedical Imaging
• Cell Biology

Background:

• Hydrophobic near-infrared (NIR) fluorophores are valuable for biological imaging.
• Controlling fluorophore emission within nanoparticles is crucial for advanced imaging techniques.
• Directed self-assembly (DSA) offers a method for creating functional nanomaterials.

Purpose of the Study:

• To engineer a bio-responsive nanoparticle system for live cell imaging.
• To investigate the mechanism of fluorescence quenching and recovery.
• To demonstrate the utility of the system for observing dynamic cellular processes.

Main Methods:

• Formation of nanoparticles via directed self-assembly (DSA) of a hydrophobic NIR-fluorophore and poloxamer P188.
• Investigation of fluorescence quenching mechanisms attributed to fluorophore hydration and aggregation.
• Stimulus-induced nanoparticle disassembly to trigger fluorescence recovery in lipophilic environments.
• Live cell imaging to assess temporal and spatial fluorescence responses.

Main Results:

• A bio-responsive nanoparticle was successfully created, exhibiting 'off-on' fluorescence switching.
• Quenching was due to fluorophore hydration/aggregation; 'on' response resulted from disassembly and lipophilic embedding.
• Intracellular delivery enabled real-time imaging of lipid droplets and other lipophilic cellular regions.
• High photostability allowed continuous imaging, facilitating observation of lipid droplet biogenesis.

Conclusions:

• The developed nanoparticle system provides a controllable platform for advanced live cell imaging.
• The 'off-on' fluorescence switching mechanism is effective for monitoring dynamic cellular events.
• This approach holds potential for further development in nanomedicine and biological research.