Stimulated Emission Depletion Microscopy Resolves Nanoparticle Assembly on a Porous Membrane Surface

Stimulated emission depletion microscopy—depending on the nature of fluorophore and sample, depletion laser power, and other experimental conditions—provides diffraction unlimited lateral resolution in the range of 20-100 nm. In this manuscript, a detailed description of such a microscope along with one of the possible imaging schemes is provided. Application of such a microscope in resolving self assembly of polymeric nanoparticles on porous alumina membrane in wet condition is demonstrated. STED microscopy resolves formation of loose linear to quasi polygonal self-assembly patterns on the membrane surface. Possible reasons for the formation of such self assembly patterns are provided