Acridine Orange

Sigma A8097

10 mg/mL solution in water

MW = 308.81

Ex: 486 - 492
Em: 516 - 532

From the Sigma web page:

Application

Acridine Orange hydrochloride solution has been used to study autophagic cell death. It has also been used for the staining of chromosomes.

Biochem/physiol Actions

Acridine Orange is a metachromatic dye which can stain DNA, RNA and acid glycosaminoglycans. At low concentration it intercalates into DNA and precipitates RNA. However, at high concentration it denatures and precipitates both RNA and DNA. Acridine Orange is also used to analyze autophagy. It goes into acidic organelles in a pH-dependent manner. At neutral pH, acridine orange gives a green fluorescence and in acidic conditions, it accumulates in the acidic organelle giving a bright red fluorescence.

From use in MBoMS: Use at ~20µM

• 1.2 µL added to 2 mL in dish

• incubate 15 min at 37

• change medium

• incubate 15 min at 37

• Replace medium with PBS

• observe with

  • B excite - G emission: dsDNA
  • G excite - R emission: RNA, ssDNA

Got good results initially, but within minutes, cells started to ball up and pull off the substrate. Will try new PBS first, then a concentration gradient of acridine orange.

Old PBS produced fast shrinking and balling up. Newer PBS was less bad. Now try with non-CO2 medium. Does it interfere with fluorescence?

No cell shrinkage in non-CO2 medium. At short exposure times, there is a background glow, but picking the right exposure takes care of that.

This is time sensitive. The red emission (which should be RNA & ssDNA) gradually fades, or overlies the green emmision (which should be ds DNA)

See attached images, taken in order 1, 2, 3. #3 is at about 15 minutes. 1 & 2 are 100x, 3 is 200x.