Preparation of malic acid cross-linked zein nanoparticles as novel vehicles for enhancing the antioxidant activity of curcumin

Curcumin (Cur), as a plant polyphenol, has many bioactive properties. However, the application of Cur is limited due to its poor water solubility and instability. In this study, malic acid (MA) was firstly applied to modulate the hydrophilicity of zein nanoparticles. Subsequently, Cur-loaded zein/malic acid composite nanoparticles (ZCM NPs) were prepared to enhance the stability and antioxidant property of Cur. The optimum mass ratio of malic acid to zein was determined as 1:5 (w/w). ZCM NPs exhibited small particle size (164.20 ± 3.67 nm) with a uniform size distribution and ideal zeta potential value (-24.00 ± 2.42 mV). The intermolecular interactions occurred in ZCM NPs were verified by Fourier transform infrared spectroscopy (FT-IR) and spectroscopic techniques. Besides, ZCM NPs demonstrated exceptional physicochemical stability against external stresses. When exposed to simulated gastroenteric fluid, the ZCM NPs exhibited a rapid and sustained release of Cur. In addition, the results of cellular uptake and antioxidant assays also showed that ZCM NPs displayed better antioxidant property than that of free Cur. These above results suggested that ZCM NPs had the potential to be a promising delivery system for Cur in the food industry. • Malic acid was used as the cross-linker and stabilizer for zein nanoparticles. • Higher physicochemical stability of zein/malic acid nanoparticles was realized. • The zein/malic acid nanoparticles increased the antioxidant activity of curcumin. • The fabricated nanoparticles exhibited a rapid and sustained release of curcumin.