Time-resolved Laser Spectroscopic Analysis of Multi-step Fluorescence Resonance Energy Transfer on Chromophore Array Constructed by Oligo-DNA Assembly

Abstract

Specific sequential arrangements of three kinds of chromophores separated by regulated distances equaling approximately one pitch of the DNA duplex (34 Å) in non-covalent molecular assembly systems are constructed using chromophore/oligo-DNA conjugates. Vectorial photoenergy transmission along the DNA helix axis by fluorescence resonance energy transfer (FRET) in a sequential chromophore array is observed and analyzed by time-resolved fluorescence spectroscopy and lifetime measurements using a femtosecond pulse laser system. The results suggest a FRET occurs on a picosecond scale between the donor chromophore and the acceptor chromophore through a mediator chromophore via a multi-step FRET over the molecular assemblies (two helical pitches, 68 Å).