AFM Force Spectroscopy Measurements of Soft, Dendritic Phytoglycogen Nanoparticles

Phytoglycogen is a naturally occurring glucose polymer produced by sweet corn in the form of compact nanoparticles with a dendritic or tree-like architecture. Properties such as deformability, unique hydration and non-toxicity make the particles desirable for applications in personal care, nutrition and biomedicine. We have used atomic force microscopy (AFM) force spectroscopy to collect high resolution force-distance maps of a large number of individual phytoglycogen nanoparticles, providing unique insights into the morphology and mechanical stiffness of the nanoparticles. Measurements performed in water revealed the highly branched, dendritic morphology of the particles for small values of the applied force. These measurements also allowed the determination of the distribution of Young’s modulus values within individual nanoparticles. Dried particles measured in air showed a dramatic increase in Young’s modulus, quantifying the effect of hydration on their mechanical stiffness. These measurements provided new insights at the single particle level of this sustainable nanotechnology.