(306b) Optimizing the Coating of Microparticles with Nanoparticles at Higher Microparticle Concentrations

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 the effects of overall particle concentration and shear flow on the interaction behavior in aqueous solutions of oppositely charged nanoparticles and microparticles. We aim to optimize the overall yield of coated microparticles at higher concentrations without uncontrolled aggregation.

The experimental system that we used to model this interaction consists of cationic chitosan nanoparticles and anionic fluorescently-tagged alginate microparticles in water. The interactions are characterized using optical and electron microscopy along with flow cytometry to quantify the level of coating. A phase diagram is developed regarding particle behavior at various ratios of nanoparticle to microparticle surface area. Multiple overall particle concentrations are also tested to see the resulting effects on the phase diagram. Known shear fields are used as well to manipulate the phase space at higher overall particle concentrations.