Wet Scans

The scanning electron microscope (SEM) has been a basic research tool for 50 years, and for all of those years scientists have been looking for better ways to observe biological samples under its beam. The problem is that biological samples cannot withstand the vacuum inside the SEM. Procedures used today include coating the specimens with an ultra-fine layer of gold, quick-freezing samples in special deep-freezes or treating them with drying solvents.

Now Weizmann Institute researchers have found a way to view samples of biological materials in their natural, “wet” state. The secret lies in producing a very thin but tough polymer capsule to enclose the sample. Dr. Ory Zik, who developed the capsule with Prof. Elisha Moses of the Physics of Complex Systems Department, says: “We came across the capsule material while researching applications for semiconductor industry techniques in the life sciences’ SEMs.”

The capsule’s polymer is unique in that it allows the electrons with which an SEM works to pass through unobstructed, giving scientists a clear view of what lies inside, without the use of tricky, tissue-distorting procedures. Researchers hope the new method will advance the study of such biological materials as lipids, which are easily destroyed by other preparation methods.

The finding was recently published in the Proceedings of the National Academy of Sciences (PNAS), USA. Zik, in cooperation with Yeda, the business arm of the Weizmann Institute, has founded a company, called QuantomiX, based on the technology.