PH-Responsive structural change of PEGylated amine-bearing nanogel explored by small angle X-ray scattering

A PEGylated nanogel sphere containing cross-linked amino groups in its core undergoes dramatic volumetric changes upon pH-change. We measured small angle x-ray scattering from the nanogel and analyzed the data with a core-shell sphere model to determine the core size upon pH-change from 8.0 to 5.8. The protonation of the poly-amine core due to the pH-change increased the core volume by over 300%. Combining the obtained core volume and the absolute intensity, we estimated the change of the core electron density.