Issue 31, 2020

14N–1H HMQC solid-state NMR as a powerful tool to study amorphous formulations – an exemplary study of paclitaxel loaded polymer micelles

Abstract

Amorphous drug–polymer formulations are complex materials and often challenging to characterize, even more so if the small molecule component itself is increasingly complex. In this work, we present 14N–1H HMQC magic-angle spinning (MAS) NMR experiments in the solid state as a promising tool to study amorphous formulations. Poly(2-oxazoline) based polymer micelles loaded with different amounts of the cancer drug paclitaxel serve to highlight the possibilities offered by these experiments: while the dense core of these polymeric micelles prevents NMR spectroscopic analysis in solution and the very similar 15N chemical shifts hamper a solid-state NMR characterization based on this nucleus, 14N is a very versatile alternative. 14N–1H HMQC experiments yield well-separated signals, which are spread over a large ppm range, and provide information on the symmetry of the nitrogen environment and probe 14N–1H through-space proximities. In this way, the overall complexity can be narrowed down to specific N-containing environments. The results from the experiments presented here represent a valuable puzzle piece, which helps to improve the structural understanding of drug–polymer formulations. It can be straightforwardly combined with complementary NMR spectroscopic experiments and other analytical techniques.

Graphical abstract: 14N–1H HMQC solid-state NMR as a powerful tool to study amorphous formulations – an exemplary study of paclitaxel loaded polymer micelles

Supplementary files

Article information

Article type
Paper
Submitted
05 3 2020
Accepted
28 5 2020
First published
29 5 2020
This article is Open Access
Creative Commons BY license

J. Mater. Chem. B, 2020,8, 6827-6836

14N–1H HMQC solid-state NMR as a powerful tool to study amorphous formulations – an exemplary study of paclitaxel loaded polymer micelles

M. Grüne, R. Luxenhofer, D. Iuga, S. P. Brown and A. Pöppler, J. Mater. Chem. B, 2020, 8, 6827 DOI: 10.1039/D0TB00614A

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