Scientists have used a scanning transmission electron microscope to image whole cells in liquid, according to research currently published online in an early edition of the Proceedings of the National Academy of Sciences.
Niels de Jonge, PhD, and colleagues at Vanderbilt University and Oak Ridge National Laboratory (ORNL) in Nashville, Tenn., added this new technique to the biology-watcher's box.
"Electron microscopy is the most important tool for imaging objects at the nanoscale – the size of molecules and objects in cells,” said de Jonge, who is an assistant professor of molecular biology and biophysics at Vanderbilt and a staff scientist at ORNL. But electron microscopy requires a high vacuum, which has prevented imaging of samples in liquid, such as biological cells.
The new technique, liquid STEM, uses a micro-fluidic device with electron transparent windows to enable the imaging of cells in liquid. The investigators reported that their technique of imaging individual molecules in a cell significantly improves and speeds, compared to existing imaging methods.
“Liquid STEM has the potential to become a versatile tool for imaging cellular processes on the nanometer scale,” de Jonge said. "It will potentially be of great relevance for the development of molecular probes and for the understanding of the interaction of viruses with cells."
"Our key innovation with respect to other techniques for imaging in liquid is the combination of a large volume that will accommodate whole cells, a resolution of a few nanometers, and fast imaging of a few seconds per image," he noted.