Dissolution, regeneration and characterization of curdlan in the ionic liquid 1-ethyl-3-methylimidazolium acetate

In this work, a novel green solvent based on the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EmimAc) with a superior dissolving ability to biomacromolecules was utilized to boost solubility of water-insoluble curdlan. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), circular dichroism (CD), and nuclear magnetic resonance (NMR) were used to characterize the structural changes of curdlan before and after regeneration. Thermal decomposition property of curdlan was also investigated using thermal gravimetric analysis (TGA). The results indicated after EmimAc treatment, the water-solubility of regenerated curdlan (RC) achieved 74.41 ± 0.63%. In addition, the hydrogen bonds in curdlan and its native triple helix structure were partially broken. In the meantime, new hydrogen bonds between EmimAc and curdlan formed. Moreover, the disruption of curdlan's original structure made it decreased thermostability and easier to dissolve in water. Therefore, this research can provide a feasible and effective approach for improving solubility of water-insoluble curdlan to enlarge its food and biomedical applications.