Reorganizations inside thermally stabilized protein/polysaccharide nanocarriers investigated by small angle neutron scattering.

We use small angle neutron scattering (SANS) to characterize the internal morphology of nanoparticles (NPs) formed by the complexation between chondroitin sulfate (CS) and bovine serum albumin (BSA) and subsequent stabilization by thermal treatment. We demonstrate that SANS can quantify the internal rearrangements and protein morphology alterations upon thermal treatment and solution conditions variations. A three-level Guinier/power-law hierarchical model identifies BSA globules, interconnected clusters of globules and higher aggregates. The effect of temperature treatment which causes protein denaturation and β-sheet inter-globular associations is captured by the model at the relevant length scales 1-100 nm. Furthermore, the nanogel behavior of the thermally treated CS/BSA NPs, which up to this moment had been characterized by light scattering, is elucidated. Loading of the nutraceutical compound β-carotene (β-C) is revealed to occur at the outer regions of the NPs. This study demonstrates that the combination of SANS and a hierarchical model for data analysis may provide very useful insights for nanocarriers which are based on polysaccharide/protein complexes and aim at biomedical applications and the food industry.