Quantifying Drug Cargo Partitioning in Block Copolymer Micelle Solutions

Understanding molecular partitioning in solution is crucial for the design of micelle-based formulations. We investigate PEO–PPO–PEO triblock copolymer micelles and their solubilization of three hydrophobic drugs: hydrochlorothiazide, indomethacin, and paclitaxel. Using NMR diffusometry, we quantify the diffusion coefficients of different species in solution, including polymers, drug cargo molecules, and solvent molecules. Polymer concentration and drug chemistry changes cause effects such as increasing partition percentages of hydrochlorothiazide and indomethacin within micelles as the F127 concentration increases from 1 to 5% w/v. This facile methodology enables quantification of drug distribution in micelles without perturbation of the solution, thus opening opportunities to understand broader processes of cargo partitioning.