A convenient approach for generating dimeric nucleic acid dyes via click-chemistry

Fluorescent dyes are essential tools for visualizing DNA and RNA. Dimeric dyes like GelGreen have gained popularity as safer alternatives to ethidium bromide (EB) due to their reduced mutagenicity and genotoxicity. In this study, we present a straightforward method to synthesize novel acridine orange (AO)-based dimeric dyes using click chemistry. Starting from acridine orange, these dyes can be synthesized in just two steps. Compared to GelGreen, these new dyes incorporate additional triazole groups in their linkers. They exhibit a maximum absorption wavelength of approximately 472 nm, which shifts to around 503 nm upon binding with DNA, allowing excitation by blue light. These dyes show minimal fluorescence in aqueous solutions, indicating that they adopt a closed conformation where the fluorescence of acridine orange is quenched due to intramolecular aggregation. The presence of DNA significantly enhances their fluorescence at around 526 nm, suggesting that DNA binding induces an open conformation. This "light-up" property makes them highly sensitive DNA dyes with a strong signal-to-noise ratio. We successfully applied these novel dyes in agarose gel electrophoresis, where they demonstrated excellent performance.