Colloidal gold labelled surface antigens on large, highly structured samples were unambiguously visualized at high magnification with backscattered electrons at 25 kV in a field emission scanning electron microscope (SEM). Secondary electron (SE) and backscattered electron (BSE) images of large and highly structured specimens are frequently disturbed by charging effects. By optimizing the thickness of the conducting carbon layer and the intensity of the incident electron beam, this problem can be overcome. The midgut of the lepidopteran larvae of Spodoptera litoralis was used as specimen. The activated 𝛿-endotoxin of Bacillus thuringiensis coupled to colloidal gold binds to the microvilli exposed to the midgut lumen.
Studer, D. and Hermann, R.
"Colloidal Gold Particles Detected on Highly Structured Surfaces of Large Samples by Backscattered Electrons in the Scanning Electron Microscope,"
Scanning Electron Microscopy: Vol. 4
, Article 22.
Available at: https://digitalcommons.usu.edu/electron/vol4/iss1/22