Date: Wednesday, April 4
Time: 12pm
Location: EN 3076
Speaker: Daniel Debroy, Department of Chemical Engineering
Title of Talk: Utilizing Oxygen-inhibited Photopolymerization to Control Size and Shape of PEGDA Hydrogel Particles
Cancer is a class of diseases characterized by hyperproliferative cell growth. Although there are many treatment options for cancer, it has been shown that combining various modalities in a single delivery vehicle is a more effective treatment than sequentially applying the same modalities. Poly(ethylene glycol) diacrylate (PEGDA) hydrogel particles are of particular interest for this application because of their biocompatibility, non-immunogenity, resistance to protein adsorption, and adjustable mechanical and chemical properties. One of the advantages of PEGDA includes its ability to be photopolymerized, which, consequently, provides increased spatial and temporal control over the hydrogel formation process. Among the existing methods to produce hydrogel particles, droplet microfluidics has gained popularity because it offers a higher degree of control over size and composition than traditional methods such as dispersion and emulsion polymerization. The photopolymerization of PEGDA droplets in microfluidic devices is susceptible to oxygen inhibition, a phenomenon in which radical species are quenched by oxygen present in the system, resulting in an incomplete gelation. Here we address these challenges by taking advantage of the usually undesirable oxygen inhibited photopolymerization to create a facile route to miniaturize hydrogels from larger, more easily produced droplets. In addition, we demonstrate that the size, network structure, and shape of PEGDA hydrogel particles can be controlled, besides generating surfaces that can be easily functionalized. Specifically, simply by changing macromer solution composition, exposure intensity, and initiator concentration, particles with sizes and shapes independent of the parent spherical droplets can be fabricated using conventional microfluidic devices.