Our group studies pressing fundamental and applied problems in nanoscience, environmental science, and immunology using a diverse set of analytical and materials techniques. We fabricate nanoparticles to study and exploit size-dependent phenomena, with applications ranging from drug delivery to in vivo and environmental sensors. Additionally, we combine our knowledge of nanoparticles and biological cells to investigate the potential biological and ecological impacts of nanoparticles added to consumer products. Finally, we apply single cell measurements techniques to probe chemical messenger synthesis and exocytosis in individual cells, including mast cells, chromaffin cells, and blood platelets.