Prompting immunostimulatory activity of curdlan with grafting methoxypolyethylene glycol

In this study, we used methoxypolyethylene glycol (mPEG) to modify CUR and unwind the triple helix structure to prompt the immunostimulatory activity. CUR-mPEG was synthesized through the substitution of hydroxides on CUR with mPEG-OH (Scheme 1). The physico-chemical properties of CUR-mPEG were characterized, including Fourier-transform infrared spectroscopy (FT-IR), hydrogen nuclear magnetic spectroscopy (1H-NMR), solubility, scanning electron microscopy (SEM), and Congo red tests. The release of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 from macrophages with the treatment of CUR-mPEG in vitro were assessed by enzyme-linked immunosorbent assay (ELISA). The cytotoxicity was characterized by CCK-8 and live/dead cell staining tests, and its antibacterial property was characterized by phagocytosis test.