Formation of the "J-aggregate-surfactant" complex for three cyanine dyes (L-21, LC-1 and PIC) in binary solutions containing cationic surfactant CPB at the concentration higher than the critical micelle concentration has been observed. The complex formation causes a significant increase of J-aggregate luminescence quantum yield and a decrease of radiative lifetime. The model of exciton self-trapping suppression in the "J-aggregatesurfactant" complex that causes changes of luminescence parameters has been proposed.

Optical spectroscopy experiments were used to study the features of cyanine dye 3,3'-dimethyl-9-(2-thienyl)-thiacarbocyanine iodide (L-21) aggregation in binary solutions DMF:Tris-HCl buffer (pH = 8) containing nucleic acids (DNA or RNA). The appearance of absorption and luminescence bands associated with J-aggregates and dimers that are formed within the minor groove of DNA has been observed. The model of L-21 J-aggregate structure is proposed. It has been found that dimers are the building blocks of L-21 J-aggregates. Disorientation in dimers caused by the minor groove curvature is reason of observation of Davydov splitting in absorption spectrum of L-21 J-aggregates. In the solution containing DNA the absorption and luminescence bands of L-21 J-aggregates exhibit the specific properties that allows the dye L-21 to be used as a fluorescent probe for DNA detection.

The inverse correlation between the exciton-lattice interaction strength and the exciton delocalization length is shown for dielectric organic nanoclusters -J-aggregates. Since the exciton delocalization length defines all optical properties of J-aggregates, it allows one to control them via the exciton-lattice interaction. We demonstrate the exciton self-trapping suppression in amphi-PIC J-aggregates as a result of the exciton-lattice interaction weakening due to the formation of a surfactant shell around J-aggregates. The control over optical properties via the exciton-lattice interaction for other types of J-aggregates is discussed.