(398ag) Anomalous Aqueous Dispersion of Hydrophobic Hedgehog Particles

Bahng, J. H. - Presenter, University of Michigan
Yeom, B., University of Michigan
Tung, S. O., University of Michigan
Kim, J. Y., University of Michigan
Kotov, N., University of Michigan

Forcing hydrophobic particles to be dispersed in water is a common requirement for numerous applications from drug delivery to oil recovery. Such dispersions are typically achieved by using surfactants or polymers that “camouflage” hydrophobic surfaces with hydrophilic groups. Aqueous dispersion of hydrophobic particles without the use of any surfactants has both technological and academic significance. In this study, we demonstrate that aqueous dispersion of hydrophobic particles without any chemical canopy is indeed possible with reengineering of the interfacial topography. We sculptured the surface of a polystyrene microsphere to feature hydrophobic and rigid ZnO nano-spikes. The Hedgehog particles (HHPs), reflective of its morphology, forms a three-phase interfacial shell; radially distal portion occupied with water and the proximal portion trapped with air both of which are interdigitated with ZnO nano-spikes. We believe the aqueous stability of hydrophobic HHPs is due to its comparable density to the medium and increased charge repulsion due to high surface area. Furthermore, we demonstrate biomedical applications where we anchored the hydrophobic HHPs onto the cell membrane which opens up the possibilities of unconventional ornaments of biological cues onto the cells and of increased complexities in cell-cell signaling.