[Bertalanffy-like fluorescence staining with 3-dimethylamino-6-methoxyacridine]

Area of Science:

• Organic Chemistry
• Cell Biology
• Spectroscopy

Context:

• Acridine dyes are widely used as fluorescent stains in biological research.
• Existing acridine dyes like acridine orange (AO) exhibit metachromasy but can fade.
• There is a need for new fluorochromes with improved stability and distinct spectral properties.

Purpose:

• To synthesize and characterize three new methoxyacridine derivatives as potential fluorochromes.
• To evaluate their efficacy in staining fixed LM- and HeLa-cells.
• To investigate the spectral properties and binding characteristics of the most promising dye.

Summary:

• Three basic acridine dyes were prepared, with dye 1 (3-dimethylamino-6-methoxyacridine) identified as the most suitable fluorochrome.
• Dye 1 demonstrated metachromatic staining of fixed cells, with distinct yellow-green nuclear fluorescence and orange/red cytoplasmic/nucleoli fluorescence.
• Enzymatic digestion confirmed dye cation binding to DNA in the nucleus and RNA in the cytoplasm/nucleoli.
• Microspectrophotometry revealed distinct absorption and emission spectra for nucleus and cytoplasm, with a red-shifted emission for cytoplasm/nucleoli, causing the metachromatic effect.
• In aqueous solution, dye 1 showed concentration-dependent spectral changes, indicating dimer formation.

Impact:

• Introduces novel acridine dyes with potential applications in cell imaging.
• Dye 1 offers improved fluorescence stability compared to existing stains.
• Provides detailed spectral and binding data for a new class of fluorochromes.
• Contributes to the understanding of dye-cell interactions and metachromasy.