The effect of NaOH and NaClO/NaBr modification on the structural and physicochemical properties of dextran

Abstract

Dextran is a polysaccharide with a high medicinal value. Thus, the chemical modifications of dextran, and the structural and physicochemical properties of its derivatives should be given focus. Dextran (M_w 5000 Da to 7500 Da) can complex with iron. In this study, dextran (M_w 5400 Da) was modified at different pH levels (8–14) by using NaOH and NaClO/NaBr. The carboxyl groups of the modified dextran were determined using infrared spectroscopy, and the carboxyl contents were compared. The results of high-performance liquid chromatography indicated that dextran was degraded during the modification. The crystallization and the structure of the carboxyl-modified dextran were investigated using X-ray diffraction, nuclear magnetic resonance, and quadrupole time-of-flight mass spectrometry. The physicochemical properties, i.e., solubility, and granule morphology, of the carboxyl-modified dextran were carefully characterized and compared. This work provides a theoretical foundation for the accurate selection of carboxyl-modified dextran and the development of a novel strategy for the preparation of metal complexes.