By enlarging cells and tissues by up five times their normal size, MIT researchers have een able to observe some of the smallest features of life, including individual neurons and synapses, by using traditional optical microscopes.
Edward Boyden, codirector of the MIT Center for Neurobiological Engineering used anew technique, called expansion microscopy, to view objects as small as 70 nanometers. Objects of this size are well below the typical 200-nanometer limit that can be achieved using conventional optical microscopes.
Discussing the new optical power with The New York Times, Dr. Boyden said: “We hope we have a technology that will allow you to scan the nervous system of entire animals.” The first study was on the brain of a mouse.
The newly devised technique uses a polymer that is commonly found in diapers. Absorbing up to 300 times its mass in water, the material has the potential to cause biological entities to swell. By fluorescently tagging the structures of interest, then infusing the tissue with the composite parts of the polymer and adding water, the science team involved were able to force the tissue to expand uniformly in all directions — up to five times its original size — while maintaining its overall organization.
According to Scicasts this means: “Pour, mix, set, add water and voila: highly detailed images of the inside of cells.” This describes the process whereby scientists fixed cell proteins in place with formaldehyde and then gently stripped the cells of their fatty membranes before treating them with labelling molecules.
The scientists hope that more fine-tuning could eventually result in the ability to expand tissues by 10 times or more. The findings have been published in the journal Science. The paper is simply titled “Expansion microscopy.”
