IEF version of the polarizable continuum model. This quantum-mechanical modeling has rationalized the absorption and fluorescence behavior given by minor groove binding and intercalation in the DNA pocket, in term of a reduced structural flexibility and polarization. Live cells and toxicity DAPI can be used for fixed cell staining. The concentration of DAPI needed for live cell staining is generally very high; it is rarely used for live cells. It is labeled non-toxic in its MSDS and though it was not shown to have mutagenicity to E. coli, it is labelled as a known mutagen in manufacturer information. As it is a small DNA binding compound, it is likely to have some carcinogenic effects and care should be taken in its handling and disposal. Alternatives The Hoechst stains are similar to DAPI in that they are also blue-fluorescent DNA stains which are compatible with both live- and fixed-cell applications, as well as visible using the same equipment filter settings as for DAPI. References See also DNA binding ligand Hoechst stain Lexitropsin Netropsin Pentamidine Staining dyes Fluorescent dyes DNA-binding substances Indoles Amidines