Simultaneous binding of a cyclophane and classical intercalators to DNA: observation of FRET-mediated white light emission.
DNA-assisted Förster resonance energy transfer (FRET) between an anthracene-based cyclophane (CP) and mono- and bis-intercalators such as propidium iodide (PI) and ethidium homodimer-1 (EHD), respectively, has been studied using various photophysical and biophysical techniques. The cyclophane and PI exhibited simultaneous binding to DNA at all concentrations studied and showed DNA-assisted FRET from the excimer of cyclophane with a FRET efficiency of ca. 71%. On the other hand, the bis-intercalator EHD, only at lower concentrations (<3 μM), can act as an acceptor for the energy transfer process with a lower efficiency of ca. 44%. At higher concentrations (>15 μM), EHD, on account of its higher binding affinity, displaces cyclophane from the DNA scaffold. Employing the ternary system comprising of the cyclophane, DNA and PI and fine-tuning the concentrations of the components in a molar ratio of 1 : 0.75 : 0.05 (CP : DNA : PI) we have demonstrated white light emission with CIE coordinates (0.35, 0.37).
Photosciences and Photonics, Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram 695019, Kerala, India. joshy@niist.res.in.
Krishnankutty S
KS
Sanju
Shameel
S
Thurakkal
Prakash P
PP
Neelakandan
Joshy
J
Joseph
Danaboyina
D
Ramaiah
D000873:Anthracenes / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D004996:Ethidium / Q000031:analogs & derivatives* / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D007364:Intercalating Agents / Q000737:chemistry*; D008027:Light; D011419:Propidium / Q000737:chemistry*
D000873:Anthracenes; D007364:Intercalating Agents; D011419:Propidium; C018533:ethidium homodimer; D004247:DNA; C034020:anthracene; D004996:Ethidium