Development and Validation of a Fluorogenic Probe for Lysosomal Zinc Release.

Area of Science:

• Biochemistry and Molecular Biology
• Cell Biology
• Chemical Sensing

Background:

• Zinc homeostasis is crucial for human health and cellular function.
• Existing methods for cellular zinc detection can be limited in accessibility or specificity.
• Development of novel, user-friendly zinc probes is essential for biological research.

Purpose of the Study:

• To synthesize and validate a novel indole-containing fluorescent probe for selective zinc ion (Zn2+) detection.
• To assess the probe's performance in complex cellular environments and under various physiological stress conditions.
• To evaluate the probe's utility in monitoring dynamic changes in intracellular zinc during cellular processes like apoptosis.

Main Methods:

• Synthesis of an indole-based fluorescent probe from accessible starting materials.
• Steady-state fluorescence studies to determine probe selectivity, sensitivity, and detection limits for Zn2+.
• Evaluation of probe interference with common low molecular weight ligands (LMWLs) and assessment of cellular toxicity.
• Application of the probe in various cell lines to monitor intracellular zinc levels under conditions of inflammation, hyperglycemia, and apoptosis.

Main Results:

• The synthesized probe demonstrated selective and reversible binding to Zn2+.
• Photoinduced Electron Transfer (PET) and Excited State Intramolecular Proton Transfer (ESIPT) mechanisms contributed to probe selectivity.
• The probe exhibited a low detection limit (0.63 μM) and minimal interference from LMWLs, except for GSH and ATP.
• The probe was non-toxic and successfully detected intracellular zinc in different cell lines, including monitoring zinc release during apoptosis in PAN-2 cells.

Conclusions:

• The developed indole-containing probe is a sensitive, selective, and non-toxic tool for detecting intracellular zinc.
• This probe facilitates the study of zinc homeostasis and its role in cellular stress responses and apoptosis.
• The probe's ease of synthesis and application makes it valuable for diverse biological research applications.