(200g) The Role of Shear Flow in Heteroaggregation Behavior of Hydrogel Microparticles and Nanoparticles

Microparticles coated with oppositely charged nanoparticles are very versatile compared to their uncoated counterparts. Nanoparticle coating is useful for improving microparticle stability and flowability. These coated particles can also be used for pH dependent tunable release, among other applications. In this work, we examine how a system of oppositely charged hydrogel microparticles and nanoparticles interacts in a shear flow environment. We aim to determine the effect that shearing has on the heteroaggregation phase behavior of the interacting particles.

The experimental system that we used to model this interaction consists of cationic green fluorescently tagged chitosan nanoparticles and anionic untagged alginate microparticles in water. The interactions are characterized using fluorescence spectroscopy to quantify the interaction taking place. Optical microscopy is used to confirm the results. Particle heteroaggregation behavior is studied at various levels of shear for different fixed concentration ratios of alginate and chitosan particles to determine the changes in the phase diagram.