The use of gold as a marker has been around in science since the mid-1800s but it didn’t come into use in microscopy until the 1960s, when gold was combined with antibodies and used as a ‘tracer’ to label proteins in cells and tissues for electron microscopy.
Gold is favoured because it has the ability to attach proteins, such as antibodies, to its surface without affecting the action of the antibody. Its use for antibody labelling in cells is known as ‘immunogold labelling’.
Fluorescently labelled antibodies are also used widely in many branches of science and have produced real advances in health, but light microscopy has limits to what fine detail can be seen inside cells and tissues. This has led to the use of gold-labelled antibodies in electron microscopy: a technique that provides ultrastructural details within cells.
The ability to attach electron-dense labels such as gold to antibodies has opened new vistas in scientific research.
In my role I have used immunogold labelling many times over the years, including a study of the mechanism that switches the meningitis bacterium from a relatively harmless state to a dangerously virulent one.
"In my role I have used immunogold labelling many times over the years, including a study of the mechanism that switches the meningitis bacterium from a relatively harmless state to a dangerously virulent one. "
Gold labels found inside the bacterium were visual proof of the factors that cause this change in virulence, as strains with the factors removed did not take up the gold-labelled antibodies.
As technology continues to advance there will still be a need to locate proteins and visualise processes within cells at high resolution – and gold will continue to be a very useful marker in these studies.
Tim Self, Head of Imaging, School of Life Sciences