Lysosomal tracking with a cationic naphthalimide using multiphoton fluorescence lifetime imaging microscopy.

Area of Science:

• Organic chemistry
• Biomedical engineering
• Analytical chemistry

Background:

• Naphthalimide derivatives are widely used as fluorescent probes.
• Developing selective and sensitive chemosensors for metal ions is crucial for biological applications.
• Iron(iii) is an important biological metal ion with implications in various diseases.

Purpose of the Study:

• To develop a naphthalimide-based chemosensor for iron(iii) ions.
• To investigate the sensing mechanism and its applicability in biological systems.
• To evaluate the lysosomal localization of the chemosensor in cancer cells.

Main Methods:

• Synthesis of a methyl piperazine-conjugated naphthalimide.
• Fluorescence spectroscopy to detect iron(iii) ions in solution.
• Cellular imaging studies using fluorescence microscopy in living cancer cells.
• Co-localization tests and fluorescence lifetime imaging microscopy (FLIM) for lysosomal localization.

Main Results:

• The naphthalimide chemosensor exhibited a turn-ON fluorescence response to aqueous iron(iii) chloride.
• The fluorescence emission was maintained in living cancer cells.
• The iron(iii) ion detection was accompanied by a pH change.
• Protonation of the methyl piperazine moiety facilitated lysosomal localization.

Conclusions:

• The developed naphthalimide chemosensor is effective for detecting iron(iii) ions in both solution and living cancer cells.
• The sensing mechanism involves pH-dependent protonation and promotes lysosomal targeting.
• This chemosensor holds potential for applications in biological imaging and diagnostics.