Neutral Red Staining Solution

Neutral red is a cationic dye, which stains nuclei in red. Neutral red staining solution is often used for nuclei counterstaining in immunofluorescence or immunohistochemical staining. This solution is acidic, and it is more suitable to stain fixed tissue or cell samples than living cells. Neutral red stains the DNA of nuclei deep red, while it stains the DNA and RNA of cytoplasm pale red.

Neutral red also serves as a pH indicator. It is red in an acidic environment. When pH gradually increased, the color of neutral red changes from red to yellow.

The staining efficiency of this solution is shown in Figure 1.

Figure 1. Image of Hela cells stained with this solution