Structure of Native and Hydrophobically Modified Phytoglycogen Nanoparticles Using Small Angle Neutron Scattering

Phytoglycogen is a highly branched polymer of glucose produced as soft, compact nanoparticles by sweet corn. Properties such as softness, porosity and mechanical integrity, combined with nontoxicity and biodegradability, make phytoglycogen nanoparticles ideal for applications involving the human body. We describe small angle neutron scattering (SANS) measurements of native phytoglycogen and phytoglycogen that was hydrophobically modified using octenyl succinic anhydride (OSA) in both its hydrogenated (hOSA) and deuterated (dOSA) forms. The data for the native particles was well described by a core-coil model, in which the outer surfaces of the particles are covered by short chains. The data for highly modified hOSA-phytoglycogen was consistent with a “raspberry” model, in which the outermost chains decorated with hOSA collapsed to form “seeds” with a well-defined size and separation. For lower DS values for both hOSA and dOSA-phytoglycogen, the data was well described using a core-shell particle geometry in which the composition of the shell was consistent with measured DS values. The results of the present study offer new insights into the morphology of phytoglycogen nanoparticles and the physical nature of their modification with OSA.