Nanoparticle Formulation Composition Analysis by Liquid Chromatography on Reversed-Phase Monolithic Silica

Multifunctional nanoparticle (NP) formulations for medical purposes have already found their way toward envisaged translation. A persistent challenge of those systems is, next to NP size analysis, the compositional analysis of the NPs with the polymer as the matrix component and the encapsulated drug, particularly in a quantitative manner. Herein, we report the formulation of poly(lactic-<i>co</i>-glycolic acid) (PLGA) NPs by nanoprecipitation and the analysis of their integrity and size by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Those NPs feature a variety of encapsulated drugs including the well-known ibuprofen (Ibu) as well as dexamethasone (Dex) and dexamethasone acetate (DexAce), with the latter being of potential interest for clinical treatment of SARS-CoV-2 patients. All those dissolved formulation compositions have been subjected to liquid chromatography on reversed-phase silica monolithic columns, allowing to quantitatively assess amounts of small molecule drug and NP constituting PLGA polymer in a single run. The chromatographically resolved hydrophobicity differences of the drugs correlated with their formulation loading and were clearly separated from the PLGA matrix polymer with high resolution. Our study identifies the viability of reversed-phase monolithic silica in the chromatography of both small drug molecules and particularly pharmapolymers in a repeatable and simultaneous fashion, and can provide a valuable strategy for analysis of diverse precursor polymer systems and drug components in multifunctional drug formulations.