EVALUATION OF PARTITION-COEFFICIENTS OF LOW-MOLECULAR-WEIGHT SOLUTES BETWEEN WATER AND MICELLES OF BLOCK-COPOLYMER OF ETHYLENE-OXIDE BASED ON DIALYSIS KINETICS AND FLUORESCENCE SPECTROSCOPY

Application of micelle-forming surfactants in various fields of techno logy and use of micelles as carriers for drug targeting requires simpl e evaluation of partitioning coefficients of different solutes between water solution and micellar microphase. A number of methods of partit ioning evaluation have been already proposed, but most of them are app licable only for fluorescent dyes or require complicated and expensive equipment, such as NMR spectrometers. In the present work two methods of the molar fraction of solubilized material determination are compa red. One of the techniques used is based on the changes in fluorescenc e spectra during solubilization. The other approach is based on the di alysis slowing down, which occurs if the solute is associated with lar ge particles (e.g. micelles). Graphic method of partition coefficient (P) evaluation is proposed and P values of a widely used anti-tumor dr ug doxorubicin and highly hydrophobic fluorophore perylene are determi ned. The comparison shows that the results of both methods give very c lose coincidence. The solubilization data were used for the calculatio n of the important parameter - the ratio of micelle volume to aggregat ion number, which makes sense of packing density of the detergent mole cules in the micelle. The comparison of this parameter calculated from the solubilization data with that obtained from light scattering expe riments is discussed. It is assumed that the dialysis technique could be used for partitioning evaluation of all substances, which may be de tected in solution.