Effect of oxidized dextran on the stability of gallic acid-modified chitosan–sodium caseinate nanoparticles

We incorporated oxidized dextran (Odex) into nanoparticles composed of gallic acid-modified chitosan (GA-CS) and sodium caseinate (NaCas). The mass ratio of GA-CS to NaCas and the pH of the reaction solution were optimized to obtain nanoparticles with excellent performance and stability. The interactions among various nanomaterials were confirmed by Fourier-transform infrared spectroscopy (FT-IR) and fluorescence spectrometer. The optimized complex nanoparticles had a diameter of approximately 131.2 nm with a polydispersity index (PDI) of 0.14, and a zeta potential of 26.2 mV. Our results showed that Odex enhanced the stability and function of GA-CS/NaCas nanoparticles (NP). At a curcumin loading of 10%, the encapsulation efficiency of Odex-crosslinked GA-CS/NaCas (NP (Odex)) was 96.2%, whereas that for uncrosslinked nanoparticles was 66.9%. Compared to the burst release profile of free curcumin in simulated GI fluids, the sustained release profile of encapsulated curcumin was observed. Radical-scavenging assays confirmed that the nanoparticles had excellent antioxidant activity themselves due to the grafting of phenolic acid on chitosan backbone. Overall, NP (Odex) with good GI stability and antioxidant activity hold promising for the oral delivery of hydrophobic bioactives.