Microscopy of gold coated diatoms

Coating of diatoms in a thin layer of metal or metal oxide has been reported for many years as a way of improving their visibility for microscopy (as examples, work I have discussed and published on slides from Horace Dall and John Dale. However it was never a common technique and is not widely used today. Recently I was sent a few slides from a fellow microscopist which contained diatoms which had had a thin (a few nm) coating of gold applied to them before mounting.

Her is an example image from one of the slides. It shows part of a diatom (likely Triceratium grande, or Triceratium favus). The resolution has been reduced for sharing here.

Gold coated diatom sample

And the slide itself.

The slide with the diatoms mounted on it

Imaging was done on my modified Olympus BHB microscope with a 60x Olympus Splan Apo NA 1.4 objective, and oblique illumination from below using white LED light. The image is a stack of 10 images (stacked using Zerene stacker) and photographed with a Canon R7 camera. The image shown has not been cropped – this was the full field of view.

Gold coating of of the diatoms certainly improves the visibility of the features, and I am looking forward to looking at the other samples. Thanks for reading, and if you’d like to know more about my microscopy or other aspects of my work, I can be reached here.