DNA dyes: toxicity, remediation strategies and alternatives

Visualization methods for loop mediated isothermal amplification (LAMP) assays

Recent advances in nucleic acid (NA) detection techniques have significantly enhanced the diagnosis of diseases caused by a range of pathogens. These NA-based methods that target specific gene sequences for identification offer high specificity. Despite the effectiveness of polymerase chain reaction (PCR), its requirement for sophisticated laboratory settings and expensive equipment restricts its accessibility, particularly in resource-limited settings. As an alternative, isothermal nucleic acid amplification methods are highly sought after due to their rapid, sensitive, and specific detection ability. Among these, loop mediated isothermal amplification (LAMP) stands out due to its simplicity, reliability, and cost-effectiveness. LAMP operates without the need for varied temperature cycles, employing a simple heating block to maintain a constant temperature, thus facilitating onsite rapid testing. In LAMP, the detection step is critical as it shows the outcome of the assay. In order to make the LAMP technique user-friendly and applicable for large scale testing, it is critical to have visual detection where the results can be observed with the naked eye. This review focuses on recent developments of LAMP visualization techniques, including the more common fluorescence, turbidity, and gel electrophoresis methods, as well as innovations in colorimetric techniques applying novel transduction methods such as nanoparticles and digital tools. Additionally, various practical applications of LAMP are discussed.

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.