Microscopy measures 40-nm-diameter fluorescent objects

Using spatially modulated illumination microscopy, scientists at the University of Heidelberg in Germany have measured nanoscale fluorescent objects beyond the limits of conventional high-resolution fluorescence microscopy. Accuracy was 90 to 95 percent for 90-nm red beads and 100-nm green beads and 80 to 90 percent for 40-nm red beads. They believe the technique, which relies on a virtual-microscopy data-analysis calibration algorithm, could serve as an alternative to or complement for electron- or x-ray-microscopy-based measurements of individual biological nanostructures within the interiors of thicker specimens such as cells. The research was detailed in the Dec. 1 issue of Applied Optics.