Overview

This project is in collaboration with Prof. Liz Orwin's group in the engineering department at Harvey Mudd. The goal of our work is to produce chitosan nanoparticles, whose antibacterial properties are essential for Orwin Lab's "brain patch" (Figure 1), a tissue-engineered treatment for Traumatic Brain Injury (TBI).

Current Progress

We synthesize nanoparticles through a two-stage process of atomization and rapid evaporation. An ultrasonic atomizer, or nebulizer, allows us to produce an aerosol of micron-scale droplets from a solution containing dissolved, commercially-available chitosan. These droplets are then directed through a heated environment where they rapidly lose water. As the solvent evaporates the strands of chitosan polymer contained in each droplet are compressed together and ultimately form spherical, dry nanoparticles of chitosan. The collection of these airborne particles exiting the evaporation stage is a current area of focus. Previous methods tested include dry inertial impaction (used to obtain the sample in Figure 2) as well as "wet impaction" with a Particle Into Liquid Sampler (or PILS, borrowed from Prof. Leila Hawkins in Harvey Mudd Chemistry). Recently, we have been successfully using a Pall Laboratory nylon membrane filter. Initial results suggest this approach results in high collection efficiency with limited contamination. It also collects the particles in such a way that they are easily recovered from the filtration device in a quantifiable amount. These are all problems we have encountered with previous collection attempts, so we hope to begin producing enough for antibacterial testing and general integration with the Brain Patch Team soon!