Viruses, organelles, cells, and organisms all have an interface or membrane, which isolates them from the environment. This surface is, compared to inorganic crystal surfaces, chemically and structurally extremely complex. In-situ approaches to an in-depth analysis, are often restricted to the microscale. Typical nanoscale methods of high-resolution microscopy and spectroscopy require exposure to vacuum or drying, and can easily change the structure of many molecules, especially proteins.
True in-situ techniques, i.e. exposure to aqueous environments, can solve the dilemma. I will show examples from organic monolayers to complete viruses, probed by infrared and sum frequency vibrational spectroscopy, and by “wet” electron microscopy (environmental SEM and STEM).
On the other hand, some biological surfaces are exposed to a more or less dry environment. For some viruses, low humidity even appears to prolong the “survival” outside cells. Nanoscale experiments on these phenomena are still in their infancy. I will show examples from a plant virus, and from a protein cage.