Immunoelectron microscopy (IEM) on a solid phase such as a carbon film is a fast and powerful way to detect and visualize surface antigens on nanoparticles by using a transmission electron microscope (TEM). Nanoparticles, in particular ones for medical applications, are often modified on the surface with soft materials to make them more soluble, less toxic, or targetable to cancerous tumors. Imaging the soft material on the surface of solid nanoparticles by electron microscopy is often a challenge. IEM can overcome this issue in cases where antibodies to any of the surface material are available, which is often the case for proteins, but also for commonly used materials such as polyethylene glycol (PEG). This effective procedure has been used traditionally for viruses and macromolecules, but it can be directly applied to nanoparticles.
Keywords: Electron microscope; Immune electron microscopy; Indirect solid phase immunolabeling; Nanomaterial; Negative stain.