Chitosan-curcumin conjugate prepared by one-step free radical grafting: Characterization, and functional evaluation.

Curcumin (Cur) is a naturally hydrophobic polyphenol, and it has a wide range of physiological functions. But the practical application of Cur is constrained by its low water solubility and poor stability. To improve these deficiencies of Cur, a novel Cur derivative (CS-Cur) was prepared by grafting chitosan (CS) with Cur through a one-step reaction of a free radical-mediated redox system. A series of characterizations provided evidence that the grafting of CS with Cur was successful. The obtained CS-Cur showed lower crystallinity and thermal properties than CS and Cur. After grafting, the water solubility of CS-Cur was found to be 9.76 ± 2.45 g/L and greatly improved. Meanwhile, the CS-Cur showed good photothermal stability, antioxidant activity, and photodynamic antibacterial activity in an aqueous solution, and it had good in vitro biosafety. This provides an idea for the design and synthesis of novel highly water-soluble Cur derivatives and also improves the practical application of Cur in aqueous systems.