An instrument built at Colorado State University lets scientists map cellular composition in three dimensions, at the nanoscale. Researchers are able to watch how cells respond to new medications at the most minute level ever observed.
According to the research team, the instrument supports the examination of cells at a level 1,000 times smaller than that of a human hair – about 100 times more detailed than was earlier possible.
At one end of the instrument is a special laser created in an argon gas-filled tube when a pulse of 60 kilovolts is discharged.
“It’s like a lightning strike in a nanosecond,” said Carmen Menoni, University Distinguished Professor in the Department of Electrical and Computer Engineering.
The laser is guided through chambers using mirrors and special lenses that focus it down to a diameter of less than 100 nanometers. In a chamber at the far side of the spectrometer, the laser hits a sample cell placed with the aid of a microscope.
Once the laser drills a miniscule hole in the cell, charged ions emitted after the tiny explosion are drawn into a side tube using electrostatic fields. The larger mass the charged particle has, the slower it moves down the tube; the time it takes an ion to reach a detector gives scientists information about its mass.
A set of special pumps creates high vacuum that sucks all air from the tube, to remove any foreign particles the sample might collide with and to ensure equally smooth sailing for all the ions.
By keeping the charge and amount of energy applied to each particle consistent, the mass becomes the key signature that provides researchers with every ion’s chemical identity.
A computer program developed in-house generates the data in a color spectrum of masses, which is then used to create a kind of topographical cell composition map.
The instrument will allow researchers to observe how well experimental drugs penetrate and are processed by cells as new medications are developed to combat disease.