Understanding micellization and quantifying drug partitioning and release rates are crucial in the design of micelle-based formulations for therapeutic cargo delivery. Here we present a study of self-assembly of a Pluronic® F127 (PEO99PPO69PEO99) triblock copolymer and its solubilization of three hydrophobic drugs, hydrochlorothiazide (HCT), indomethacin (IND) and paclitaxel (PTX). Using NMR diffusometry, we have quantified diffusion coefficients and relative sizes of different species in aqueous solution, including the polymers, drug cargo molecules and solvent. The cargo partition coefficient is given by the ratio of model drug concentration in the micellar phase to that in the aqueous phase. We are investigating the effects of polymer concentration, drug chemistry as well as drug concentration on cargo partitioning. As the polymer (micelle) concentration increases, the partition percentages of HCT and IND in micelles are also enhanced (figure below). Small-angle neutron scattering (SANS) results on micelle dimensions are in agreement with our NMR observations, which reveals a growth in the micellar core radius and aggregation number in the meantime a decrease in the volume % of the solvent in cores. This facile and non-invasive NMR method allows the measurement of drug distribution in a micellar system and opens opportunities to understand the dynamic processes of drug partitioning and release in micelles.

Quantifying drug cargo partitioning in pluronic block copolymer micelles

2019 Spring National Meeting

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