Overview of Fluorescence Staining Solutions

Commonly used fluorescence staining solutions

1. Propidium Iodide (PI)

2. DAPI

3. Acridine Orange (AO)

Each staining solution has different functions and characteristics.

PI and DAPI are used to stain dead cells with damaged membranes so that these solutions can penetrate the inner part of the cells and stain the nucleus.

AO is a permeable staining solution that can penetrate both live and dead cells, making it useful for counting the total number of cells.

Main target for staining

Propidium Iodide	DNA
Acridine Orange	DNA and RNA
DAPI	DNA

Wavelength of staining solutions

(When bound to either DNA or RNA)

	PI	AO	DAPI
Excitation	535 nm	500 nm 460 nm (RNA)	458 nm
Emission	617 nm	525 nm 650 nm (RNA)	461 nm

Properties of staining solutions

	PI	AO	DAPI
Molecular weight	668.39 g/mol	301.82 g/mol	277.32 g/mol
Permeability	X	O	X

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