Figure 2From: pH-responsive drug delivery system based on hollow silicon dioxide micropillars coated with polyelectrolyte multilayersMicroscopy characterization of the SiO 2 micropillars. SEM image of released micropillars with a diameter of 1.8 μm (A), and dark-field TEM images of a detached micropillar with a length of 26 μm (B) and a detail of the uniform SiO2 wall and hollow structure on the micropillar tip (C).Back to article page