Influence of Dye Hydrophobicity on the Efficiency of Fluorescence Resonance Energy Transfer Between Dyes in Surfactant Micelles

The fluorescence resonance energy transfer (FRET) between dyes DiOC(n) (n=2, 6, 9, and 18) and DiI in aqueous sodium dodecyl sulfate solutions has been studied using the steady-state fluorescence spectroscopy technique. High values of the Stern-Volmer constant (K-SV) obtained indicate the long-range dipole-dipole interaction between an excited donor DiOC(n) and a ground-state acceptor DiI. The energy transfer efficiency (E) has been analyzed, by basing on both the donor luminescence quenching and the acceptor luminescence enhancement. An increase in E with the donor hydrophobicity is explained in frames of the Forster theory due to shortening the distance between the donor and the acceptor in a SDS micelle.