Single Molecule Measurements of the Morphology and Stiffness of Acid-Hydrolyzed Phytoglycogen Nanoparticles

Phytoglycogen (PG) is a soft and highly branched nanoparticle that is produced in the kernels of sweet corn. Its deformability, biocompatibility and digestibility make PG nanoparticles ideal for applications in personal care, nutraceuticals, and drug delivery. Chemical modifications can be used to tune the physical and chemical properties of the particles, adapting the nanoparticles for specific applications. We have explored the effect of acid hydrolysis, a process in which bonds between the glucose subunits can be broken through exposure to dilute acid at high temperature, and measured changes to the radius, deformability, and outer chain length of the PG particles. By performing atomic force microscopy (AFM) force spectroscopy, we have generated high resolution maps of the Young's modulus E of the hydrated acid-hydrolyzed PG nanoparticles, characterizing the dependence of the particles' size and deformability on the hydrolysis time. Intermediate hydrolysis times produced changes in both the inner and outer regions of PG, whereas long hydrolysis times produced significant overall decreases in E.