Simultaneous binding of a cyclophane and classical intercalators to DNA: observation of FRET-mediated white light emission

• Published in: Physical chemistry chemical physics : PCCP Vol. 17; no. 20; pp. 13495 - 13500
• Main Authors: Sanju, Krishnankutty S, Thurakkal, Shameel, Neelakandan, Prakash P, Joseph, Joshy, Ramaiah, Danaboyina
• Format: Journal Article
• Language: English
• Published: England 28.05.2015
• Subjects: Affinity; Anthracenes - chemistry; Binding energy; Deoxyribonucleic acid; Displacement; DNA - chemistry; Emission; Energy transfer; Ethidium - analogs & derivatives; Ethidium - chemistry; Fluorescence Resonance Energy Transfer; Fretting; Intercalating Agents - chemistry; Iodides; Light; Propidium - chemistry; White light
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c5cp00208g

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).