The goal of this project is to develop biopolymer nanoparticles of varying surface charge that can be used as encapsulation vehicles for food applications and drug delivery, as well as in separation processes. In each of these applications, the particle surface charge and electrostatic interactions are key properties of the system. Chitosan and alginate-coated chitosan nanoparticles are produced by ionic gelation methods under mild, room-temperature conditions. Chitosan and alginate are edible, biocompatible and biodegradable polymers, and are therefore frequently used as food additives and in biomedical applications.

In this experimental study, several types of chitosan nanoparticles were synthesized with varying zeta potentials and sizes. The various chitosan nanoparticles were then coated with a layer of alginate to form core-shell nanoparticles where the surface charge can be further controlled. The nanoparticle size distribution and zeta potential were characterized using a zetasizer, and the average zeta potentials range from 0 to 50 mV while the diameters range from 200-500 nm. We will present findings on how chitosan, alginate and cross-linker concentrations determine the nanoparticle surface charge and size. We will relate the results to concepts from the literature regarding the complexation of polyelectrolytes. Results will also be presented on the effect of nanoparticle composition on the release rates of encapsulated substances.