Graduate Seminar: Neutron Scattering Techniques to Characterize the Structure and Dynamics of Colloidal Phytoglycogen Dispersions

Event Details

  • Speaker(s): John Atkinson
  • Date:
  • Time: 3:00 PM
  • Location: MacN 318

Abstract

Neutron scattering is a powerful technique for probing concentrated colloidal suspensions. The fundamentals of neutron scattering will be covered and its application to the characterization of phytoglycogen will be discussed. Phytoglycogen is a natural, monodisperse, dendrimeric nanoparticle that can be isolated from corn whose interactions with water provide unique properties that can be applied to the cosmetic and biomedical industry. Small angle neutron scattering measurements allowed us to determine the radius of the phytoglycogen nanoparticles (17.4 ± 1.6 nm), establish the inter-particle spacing as a function of concentration, and obtain an estimate of the hydration of the particles (nH = 15.8 per monomer). These measurements indicated a particle of uniform density, with no indication of molecular crowding up to a concentration of 22.4% w/w. This result is consistent with the observation of low viscosity of phytoglycogen dispersions at lower concentrations. Quasielastic neutron scattering measurements provided detailed information regarding the dynamics of water in these dispersions, showing that the translation of the hydration water was subdiffusive and providing an additional value for the hydration of the particles (nH = 13.9 ± 2.3 per monomer). These results indicate that the number of water molecules associated with the phytoglycogen particles per monomer is comparable to that of free glucose units. When considered as a particle, there are approximately 1.9 million water molecules associated with each phytoglycogen nanoparticle (150%-175% of its own mass).

Further Details

The talk is from 3-4 pm (snacks at 2:30!). Make sure to follow the Graduate Seminar Series on Facebook.