Coumarin Excimer Nanotube for Long-Time Lysosome Tracking

Area of Science:

• Biochemistry
• Molecular Biology
• Nanotechnology

Background:

• Lysosome abnormalities are linked to various diseases, necessitating long-term tracking for accurate diagnosis.
• Existing long-term lysosome imaging probes lack sufficient biocompatibility, and peptide-based probes degrade easily in lysosomes.

Purpose of the Study:

• To design and synthesize a novel, biocompatible peptide-based probe for long-term lysosome imaging.
• To investigate the probe's self-assembly into nanotubes and its fluorescence properties in acidic environments.

Main Methods:

• Rational design of a d-amino acid-containing peptide probe (Cou-D/L-CBT) with a coumarin moiety and CBT group.
• Intracellular glutathione (GSH)-initiated click reaction for self-assembly into nanotubes under acidic conditions (pH 4.8).
• In vitro and cell experiments to evaluate probe biocompatibility, assembly, fluorescence, and imaging duration.

Main Results:

• Cou-D/L-CBT self-assembled into nanotubes (156 nm outer diameter) under reduction and pH 4.8, exhibiting 'turn-on' coumarin excimer fluorescence at 550 nm.
• Cell experiments demonstrated significantly prolonged lysosome fluorescence imaging (29 h) compared to a control probe (6 h).

Conclusions:

• The d-amino acid-containing peptide probe Cou-D/L-CBT offers enhanced stability and biocompatibility for long-term lysosome imaging.
• This probe has potential applications in the sensitive in vitro diagnosis of lysosome-related diseases.