Hydrogels have proved successful in integrating water soluble medications for extended release drug delivery. However, many hydrophobic drug molecules have been found to integrate poorly into the polar, water based environment of the hydrogel. A solution is to encapsulate the drug molecule in a polymer shell creating a vessel which can integrate well into the hydrogel environment; however, the polydispersity of these vessels when formed under earth’s gravitational conditions cause inconsistent rates of delivery. Under microgravity, the major force acting on self-assembly should be surface tension and naturally should favor small, spherical particles of similar shape and size. Should this be true, and the system assembles with a high level of monodispersity, it could be a superior mechanism for the controlled release of hydrophobic molecules. In order to determine whether microgravity environments could positively impact the self-assembly of cross-linked micelles for drug delivery, a series of mini-labs were constructed. One flight experiment mini-lab was sent to the International Space Station in July of 2018 with the Student Spaceflight Experiments Program (SSEP), while triplicate control groups were performed on Earth under normal gravity conditions. Indigo dye was used as a mock hydrophobic drug molecule that can be encapsulated within polymeric micelles. The experimental system introduced the indigo dye to poly(ethylene-<i>co</i>-glycidyl methacrylate) or PEGMA polymer shavings, and was allowed to self-assemble over several weeks. Finally, a cross-linking agent was added to enhance chemical stability for re-entry to Earth. Confocal microscopy, atomic force microscopy, dynamic light scattering, scanning electron microscopy, and fluorescence microscopy were used to characterize the particles of hydrogel. These techniques give both qualitative and quantitative insight into the size, shape, and polydispersity of the particles under both microgravity and normal gravity conditions. Analysis so far has indicated that there are obvious structural differences between the flight experiment and ground truth control groups; however, the extent and impacts of these differences are being investigated.

Effects of microgravity on the self-assembly of PEGMA and drug delivery systems

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.