Small Angle X-Ray Scattering Data Analysis and Theoretical Modelling for the Size and Shape Characterization of Drug Delivery Systems Based on Vitamin E TPGS Micelles

We developed a simple two-dimensional/two-components theoretical model that describes the structure and functionality of a VitE-TPGS system of micelles assuming a hydrophobic inner core and an outer hydrated hydrophilic shell. We then conceptually applied the developed methodology to a simple system of VitE-TPGS micelles unloaded and loaded with an active pharmaceutical ingredient, eltrombopag, to verify if the model could reliably monitor the size change of the micelle upon loading. The fit of laboratory Small Angle X-Ray Scattering data against such model allows us to extract absolute values of the micelles size under a spherical shape hypothesis as well as the distribution within the system between components and level of hydration. The intensity scale of the SAXS experimental data needs to be normalized to a reference standard (pure water) to get absolute scattered intensities. The mathematical model which has been devel-oped under a general hypothesis of ellipsoidal micelles, is applied to our experimental data under the simpli-fied spherical assumption, which suitably fits our experimental data.(c) 2022 American Pharmacists Association. Published by Elsevier Inc. All rights reserved.

Automated summary

We developed a simple theoretical model that describes the structure and functionality of a VitE-TPGS micelle system. We applied the model to investigate the size change of the micelle upon loading with eltrombopag. By fitting laboratory data, we were able to extract information about the size, components, and hydration level of the micelles.