The use of submicroscopic gold particles combined with video contrast enhancement as a simple molecular probe for the living cell.

We describe a new approach to probe the molecular biology of the living cell that uses small colloidal gold particles coupled to specific ligands. They are visualized in cells by bright-field, video enhanced contrast microscopy. We describe the basic aspects of the technique and provide examples of applications to intracellular motility, cell membrane dynamics, receptor translocation, internalization, and intracellular routing. We also provide examples of the use of this approach in immunospecific labelling of cells and tissue sections.