Exact determination of the degree of substitution of high molar mass hyaluronan by controlling the conformation in solution. (15th January 2019)

• Record Type: Journal Article
• Authors: Ret, Davide; Steiner, Gökçe; Gentilini, Stefano; Knaus, Simone
• Is Part Of: Carbohydrate polymers. Volume 204(2019)
• Page Start: 124
• Page End: 130
• Publication Date: 2019-01-15
• Subjects: Hyaluronic acid -- Polyelectrolytes -- Quantitative 1D-NMR spectroscopy -- Proton mobility -- Conformation; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2018.10.003
• Languages: English
• ISSNs: 0144-8617

Abstract

Graphical abstract: Highlights: Quantitative 1D-NMR analysis of high molecular weight HA derivatives is feasible. Variation of ionic strength is a powerful tool to enhance quality of NMR spectra. Full proton mobility can be achieved by controlling conformation in solution. A correct DS can be determined below the concentration of chain overlap point. Proton mobility of the reference peak should be checked with an internal standard. Abstract: The purpose of the present study was the development of an accurate method to determine the degree of substitution (DS) of modified hyaluronic acid (HA) by proton nuclear magnetic resonance ( 1 H NMR) spectroscopy. The influence of the effect of ionic strength and pH on 1 H NMR spectra of HA was studied. The results showed a correlation between the conformation of HA in solution and the quality of the 1 H NMR spectra. The best spectra with full proton mobility are obtained when HA is dissolved in D2 O with 2 M NaCl or D2 O with 0.1 M NaOD with a maximum concentration of 5 mg/ml. Under those conditions the size of the polymer coils is reduced below the concentration of chain overlap point, all the protons show the same response and a correct degree of substitution can be determined.