Nano-scale control of energy transfer in the system “donor–acceptor”

Fluorescence resonance energy transfer (FRET) in a cascade scheme between three amphiphilic dyes 3,3′-dioctadecyloxacarbocyanine perchlorate (DiOC18(3), donor), 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiIC18(3), acceptor/donor) and 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindodicarbocyanine perchlorate (DiIC18(5), acceptor) has been investigated at low dye concentration (10−5 mol/l) in water–micellar solutions due to a forced assembling of dyes in nanoscale volume. The experimental data have revealed that sodium dodecyl sulfate (SDS) micelles solubilize dye molecules such that their hydrophilic heads are in contact with water, while hydrophobic tails are embedded into the hydrocarbon core of the micelle. FRET efficiency has been found to depend on the concentration of dyes in micelles and the most effective when each SDS micelle contains 1 donor (DiOC18(3)), 2 acceptor/donor (DiIC18(3)) and 4 acceptor (DiIC18(5)) molecules.