Question

NucGreen stains dying cells that have compromised plasma membranes. What could cause false positives?

Answer 1

Answer:

The membrane-impermeable NucGreen stain is a high-affinity DNA stain that stains cells with compromised cell membranes and does not enter living cells. Since this reagent stains cells that lack plasma membrane integrity, it is extremely useful to measure viability and to measure cytotoxicity in kinetic live-cell assays.

What causes false positive results

NucGreen dye emits a fluorescent signal when bound to DNA of non viable cells. The number of NucGreen-positive cells was determined by measuring the fluorescent intensity/well using a fluorescent plate reader. The staining intensity increases with time if cells are not washed prior to imaging. Hence improper washing of cells prior to imaging will lead to increased fluorescent intensity and hence will lead to false positive results with respect to number of NucGreen positive (non viable cells).

Summary: To obtain accurate results in NucGreen staining, proper washing prior to imaging is vital.