DAPI Oligonucleotide Labeling
Min Li,* Robert S. Wu and Jane S. C. Tsai
12/23/2014
Science Direct
DAPI (40,6-diamidino-2-phenylindole) is a fluorescent multicyclic dye that has been frequently utilized as a DNA-specific probe for flow cytometry, chromosome staining, DNA visualization and quantitation.1,2 The interaction between DAPI and polydeoxynucleotides has been extensively studied in the past 30 years and many efforts have been devoted to investigating the DAPI binding mechanism to nucleic acids.37 DAPI binds to the minor groove of A-T rich sequences of duplex DNA with very high affinity (apparent association constant 105–107 M1 range)1,7 and the bound DAPI fluoresces very strongly, in contrast to unbound DAPI molecules that display very weak fluorescence (quantum yield 0.04).8 Fluorescent dyes with such fluorogenic property have been employed in the design of DNA probes that are capable of detecting specific DNA sequences. In such cases, a dye is usually attached to a complementary oligonucleotide probe via covalent linkage.9
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