What is acridine orange?
Acridine orange (AO) is a fluorescent dye commonly used to count cells emitting in different colors based on the type of nucleic acid it binds to. This color distinction makes AO a great tool for identifying specific types of molecules within cells. It is a permeable dye penetrating both live and dead cells regardless of membrane intactness. This unique feature makes it useful for staining all cells, so it is widely used for various testing such as viability testing and cell cycle assay.
Characteristics of acridine orange
The advantage of AO is its permeability. Due to its weakly basic characteristic, it can cross cell membranes and stain nucleic acids without having to break the membranes physically.
Dual-Color Fluorescence:
Acridine orange has the ability to emit different colors depending on its binding target:
Green for single-stranded DNA or RNA
Red for DNA.
This unique feature becomes useful when differentiating between DNA and RNA or single-stranded and double-stranded DNA in cells.
High Sensitivity and Contrast:
AO is highly sensitive and provides strong contrast, making it ideal for detecting nucleic acids in cells. In a recent study, the comparison between the AO and Gram stain was conducted which concluded with an interesting result that AO was more sensitive than Gram stain and that AO provided much clear detection and differentiation [1].
Properties
Molecular weight : 265.35 g/mol
Excitation / emission :
Bound to DNA > 500 nm / 526 nm (red)
Bound to ssDNA or RNA > 460 nm / 650 nm (green)
Permeability : O
References:
NanoEntek provides automated cell counters using acridine orange (AO) staining solution.
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