Fabrication and characterization of resveratrol loaded zein-propylene glycol alginate-rhamnolipid composite nanoparticles: Physicochemical stability, formation mechanism and in vitro digestion

In this study, resveratrol loaded zein-propylene glycol alginate-rhamnolipid composite nanoparticles were fabricated to overcome the limitations of resveratrol such as water insolubility and chemical instability. Effect of rhamnolipid level on properties of the composite nanoparticles was characterized systematically. Incorporation of rhamnolipid was proved to modulate the encapsulation efficiency, physicochemical stability as well as digestion behavior of composite nanoparticles in simulated gastrointestinal tract. Fluorescence spectrum and circular dichroism analyses revealed that resveratrol and rhamnolipid altered the micro-environment and secondary structure of the protein in different solvents (colloidal dispersions or aqueous ethanol solutions). Fourier transform infrared spectroscopy (FTIR) confirmed that hydrogen bonds, hydrophobic effects and electrostatic interactions contributed to the formation of resveratrol loaded composite nanoparticles. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) patterns manifested that the amorphous nature of resveratrol encapsulated. Observation of zein-propylene glycol alginate-rhamnolipid composite nanoparticles by field emission scanning electron microscopy (FE-SEM) confirmed the globular nanoparticles and their potential to be an effective vehicle of resveratrol to be supplemented to food systems.