Characterization and interfacial rheological properties of nanoparticles prepared by heat treatment of ovalbumin-carboxymethylcellulose complexes

The objective of this study was to investigate the physicochemical and interfacial rheological properties of ovalbumin (OVA)-carboxymethylcellulose (CMC) nanoparticles. The OVA/CMCs nanoparticles were prepared by heating (90 °C, 30 min) the electrostatic self-assembly complexes between OVA and CMC of different charge density (CMC 0.7 and CMC 1.2) at pH 4.4. The results showed that the OVA/CMC 0.7 nanoparticles exhibited larger size and lower surface net potential than OVA/CMC 1.2 nanoparticles. Atomic force microscopy (AFM) imaging and ultra-small angle X-ray scattering (USAXS) results suggested that the shape of the particles was approximately spherical, and the structure of OVA/CMC 1.2 nanoparticles was more compact than that of OVA/CMC 0.7. The pyrene fluorescent probe indicated that the OVA/CMC 1.2 nanoparticles had a stronger hydrophobicity than OVA/CMC 0.7 nanoparticles in the range of pH 4–7. As the pH and the ionic strength increased, the average diameter of OVA/CMC nanoparticles would increase (<400 nm), while the average size of the nanoparticles did not change significantly after 30 days of storage at room temperature. The interfacial rheological experiments showed that the permeation and rearrangement rates of OVA/CMC nanoparticles decreased significantly at oil-in-water interface, and the surface pressure and interfacial dilatational modulus were lower than the native OVA/CMC complexes. These findings suggest that OVA/CMC nanoparticles formed by heat induction can be used to construct lipid-soluble nutrient delivery vehicles.