DAPI (4',6-Diamidino-2-Phenylindole, dihydrochloride) is a popular blue DNA dye that is used as a nuclear counterstain in fluorescence microscopy, chromosome staining and flow cytometry. The dye binds to the minor groove of dsDNA with approximately 20-fold fluorescence enhancement, with higher affinity for A-T rich regions. Also see DAPI dilactate, a more water soluble form of the dye.
<ul>
<li>Classic blue nuclear counterstain for fixed cells</li>
<li>Can be used at higher concentrations to stain live cells</li>
<li>&lamba;_Ex/&lamba;_Em = 358/461 nm (with DNA)</li>
<li>Off-white solid soluble in H₂O</li>
<li>Store at 4°C and protect from light, especially in solution</li>
<li>C₁₆H₁₇Cl₂N₅</li>
<li>MW = 350.25</li>
<li>[28718-90-3]</li>
</ul>