Interaction of nanogel with cyclodextrin or protein: Study by dynamic light scattering and small-angle neutron scattering

The structure of hydrogel nanoparticles (CHP nanogels), formed by self-aggregation of cholesterol-bearing pullulan (CHP) was studied by dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The interactions between the CHP nanogel and methyl-β-cyclodextrin (CD) or protein (hen egg white) were also investigated. It was revealed by SANS that the nanogels were spherical in shape with a radius of 6.7 nm. The following two functions were disclosed. (1) CHP nanogels were dissociated by the addition of CD and formed inclusion complexes with cholesteryl groups, leading to suppression of hydrophobic interaction between the cholesteryl groups. (2) The nanogel behaved as a molecular chaperone (heat shock protein-like activity) when CHP nanogel was mixed with hen egg white and heated up to 75 °C. The egg white aqueous solutions with CHP nanogel remained transparent while the egg white without CHP nanogel became opaque.