Solid-state NMR characterization of tri-ethyleneglycol grafted polyisocyanopeptides

• Published in: Magnetic resonance in chemistry 2016-04, Vol.54 (4), p.328-333
• Main Authors: Zinkevich, T., Venderbosch, B., Jaspers, M., Kouwer, P. H. J., Rowan, A. E., van Eck, E. R. H., Kentgens, A. P. M.
• Format: Article
• Language: English
• Subjects: 13C; Addition polymerization; Amino Acids - chemistry; Biomedical materials; Bundling; Carbon; Carbon-13 Magnetic Resonance Spectroscopy; Dynamics; Ethylene Glycol - chemistry; Gelation; hydrogels; Isocyanates - chemistry; Magnetic Resonance Spectroscopy - methods; NMR; Nuclear magnetic resonance; Origins; Peptides - chemistry; polyisocyanides; Proton Magnetic Resonance Spectroscopy; structure characterization
• ISSN: 0749-1581; 1097-458X
• DOI: 10.1002/mrc.4379

In aqueous media, ethylene glycol substituted polyisocyanopeptides (PICPs) change their state (undergo a sol‐to‐gel transition) as a response to temperature. This makes them promising materials for various biomedical applications, for instance, for controlled drug release and non‐damaging wound dressing. To utilize PICP in biomedical applications, understanding of the origin of the gelation process is needed, but this is experimentally difficult because of the notoriously low gelator concentration in combination with the slow polymer dynamics in the sample. This paper describes a detailed characterization of the dried state of PICPs by solid‐state NMR measurements. Both the 13C and the 1H NMR resonances were assigned using a combination of 1D cross‐polarization magic angle spinning, 2D 13C–1H heteronuclear correlation spectra and 1H–1H single quantum–double quantum experiments. In addition, the chemical groups involved in dipolar interaction with each other were used to discuss the dynamics and spatial conformation of the polymer. In contrast to other PICP polymers, two resonances for the backbone carbon are observed, which are present in equal amounts. The possible origin of these resonances is discussed in the last section of this work. The data obtained during the current studies will be further used in elucidating mechanisms of the bundling and gelation. A comprehensive picture will make it possible to tailor polymer properties to meet specific needs in different applications. Copyright © 2015 John Wiley & Sons, Ltd. The structure of polyisocyanopeptide is investigated by solid‐state NMR spectroscopy. We revealed an existence of two conformations in equal ratios. The origin of these conformations is discussed.