Responsive Fluorophore Aggregation Provides Spectral Contrast for Fluorescence Lifetime Imaging

Area of Science:

• Chemical Biology
• Molecular Imaging
• Biophysical Chemistry

Background:

• Fluorophore emission lifetimes are sensitive to their microenvironment, changing upon interaction with macromolecules or aggregates.
• This sensitivity offers opportunities for developing responsive probes that signal changes in molecular state.
• Self-assembly and aggregation can modulate the photophysical properties of fluorescent molecules.

Purpose of the Study:

• To design and characterize a novel fluorescent probe with aggregation-dependent lifetime changes.
• To investigate the probe's response to biological reducing agents in vitro.
• To explore the potential of such probes for responsive lifetime imaging.

Main Methods:

• Synthesis of a cyanobenzothioazole-fluorescein conjugate (compound 1).
• Spectroscopic analysis of fluorescence lifetime changes.
• In vitro experiments using buffered systems and the reducing agent glutathione.

Main Results:

• Compound 1 exhibited a decrease in fluorescence emission lifetime upon reduction-induced aggregation.
• The observed lifetime changes were dependent on the presence of glutathione.
• The probe demonstrated responsiveness to a biologically relevant reducing agent.

Conclusions:

• The developed cyanobenzothioazole-fluorescein conjugate serves as a responsive probe whose lifetime is altered by aggregation.
• Reduction-induced aggregation, triggered by glutathione, leads to a measurable decrease in fluorescence lifetime.
• This work presents a promising strategy for creating self-aggregating, responsive probes for lifetime imaging.