Used in electron microscopy to enhance contrast of biological specimens such as viruses, bacteria, and cellular organelles. It binds to the surface of macromolecules and provides a dense, electron-scattering layer that outlines structural details. Commonly applied in virology and structural biology for quick, reliable imaging of sample morphology. Also used in histology as a component of staining protocols for tissue sections, improving visualization of cellular components under light and electron microscopes.