Abstract: The study of the properties of the visible spectra and fluorescent spectra of safranine T(ST)in the solution of anionic surfactants(AS)was reported.The results showed that STformed complex with ASmolecule when the concentration of ASwas low, and the absorbance and fluorescence intensities of ST, therefore, decreased.Anon-fluorescent dimeric dye was formed on the formation of premiceller aggregation of ASwhen the concentration of ASwas made higher, and thus the fluorescence intensity decresed dramatically,and a new peak in visible spectra appeared.When the surfactant concentration was increased above the critical micelle concentration(CMC), the dimeric dye dissociated, and a new fluophore with a high quantum yield was formed.The posibility of using the non-fluorescent dimeric dye as a fluorescent probe for deoxyribonucleic acid was also studied.The dimeric dye showed a highly DNAbinding constant and significant change of fluorescent behaviour was observed when the dimeric dye interacted with double strands DNA.It was obvious that the dimeric dye may be used as a good DNA probe.

Key words: Safranine T, Anionic surfactant, DNA, Visible spectra, Fluorescent spectra