Spectroscopic study of interactions between dye molecules in micelle and liposome nanovolumes

The efficiency of Forster resonance energy transfer (FRET) between pairs of different dyes in the nanovolumes of surfactant micelles and liposomes was studied using optical spectroscopy methods. More efficient FRET with the same solution concentrations of the dyes was observed in liposomes despite the greater diameter of liposomes compared with micelles (100 and 5 nm). Calculations showed that the observed effect was explained by the smaller amount of liposomes in the solution and, consequently, the larger local concentration of the dyes in the liposome lipid bilayer. It was shown that not only the spectral overlap integral and the Forster distance but also specific interactions between molecules in the nanovolume (electrostatic, vander-Waals, and steric) that were governed by structural features of the molecules affected the FRET efficiency.