Flavylium-Based Hypoxia-Responsive Probe for Cancer Cell Imaging.

Area of Science:

• Biomedical Engineering
• Chemical Biology
• Molecular Imaging

Background:

• Hypoxia is a hallmark of cancer, driving tumor progression and treatment resistance.
• Developing specific and sensitive probes for hypoxia detection is crucial for cancer diagnosis and therapy.

Purpose of the Study:

• To synthesize and characterize a novel hypoxia-responsive probe, AZO-Flav, for detecting hypoxic conditions in cancer cells.
• To evaluate the probe's sensitivity, specificity, and response kinetics in vitro and in cancer cell models.

Main Methods:

• Synthesis of AZO-Flav, a flavylium dye with an azo group.
• In vitro enzymatic assays using reductase and reduced nicotinamide adenine dinucleotide phosphate (NADPH).
• Fluorescence imaging in HepG2 cancer cells under hypoxic and normoxic conditions.

Main Results:

• AZO-Flav demonstrated rapid (2 min) and sensitive (0.4 μM LOD) reductase-catalyzed reduction, yielding a fluorescent product (Flav-NH).
• The probe exhibited high specificity, unaffected by biological interferences like reducing agents and biothiols.
• A significant fluorescence increase (10-fold at 15 min, 26-fold at 60 min) was observed in hypoxic cancer cells compared to normoxic conditions.
• Inhibition of the fluorescence signal by diphenyliodonium chloride (DPIC) confirmed the involvement of reductases in hypoxia.

Conclusions:

• AZO-Flav is a highly effective probe for detecting hypoxic environments in cancer cells.
• The probe's rapid response, high sensitivity, and specificity make it a promising tool for in vivo hypoxia imaging.