Immunogold labeling

Immunogold labeling or Immunogold staining (IGS) is a staining technique used in electron microscopy. This staining technique follow the same patterns of the Indirect immunofluorescence : colloidal gold particles are most often attached to secondary antibodies which are in turn attached to primary antibodies designed to bind a specific antigen or other cell component. Gold is used for its high electron density which increases electron scatter to give high contrast 'dark spots'.

First used in 1971, immunogold labeling has been applied to both transmission electron microscopy and scanning electron microscopy, as well as brightfield microscopy. The labeling technique can be adapted to distinguish multiple objects by using differently-sized gold particles.

Immunogold labeling can introduce artifacts, as the gold particles reside some distance from the labelled object and very thin sectioning is required during sample preparation.

Immunogold labeling was first used in 1971 by Faulk and Taylor to identify Salmonella antigens. It was first applied in transmission electron microscopy (TEM) and was especially useful in highlighting proteins found in low densities, such as some cell surface antigens. As the resolution of scanning electron microscopy (SEM) increased, so too did the need for nanoparticle-sized labels such as immunogold. In 1975, Horisberger and coworkers successfully visualised gold nanoparticles with a diameter of less than 30 nm and this soon became an established SEM technique.

First, a thin section of the sample is cut, often using a microtome. Various other stages of sample preparation may then take place.

...
Wikipedia