New nanoscale device can measure mass of single molecule

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London, July 23 (ANI): For the first time, researchers at California Institute of Technology (Caltech) have used nanoscale devices to develop a technique to determine the mass of a single molecule, in real time.

Traditionally, the mass of molecules is measured using mass spectrometry, in which samples consisting of tens of thousands of molecules are ionized, to produce charged versions of the molecules, or ions.

The ions are then directed into an electric field, where their motion (which is choreographed by both their mass and their charge), allows the determination of their so-called mass-to-charge ratio. From this, their mass can ultimately be ascertained.

The new technique, developed over 10 years of effort by Dr. Michael L. Roukes, at the Caltech and his colleagues, simplifies and miniaturizes the process through the use of very tiny nanoelectromechanical system (NEMS) resonators.

The bridge-like resonators, which are 2 micrometers long and 100 nanometers wide, vibrate at a high frequency and effectively serve as the "scale" of the mass spectrometer.

"The frequency at which the resonator vibrates is directly proportional to its mass," Nature quoted research physicist Askshay Naik, the first author of a paper, as saying.

Changes in the vibration frequency, then, correspond to changes in mass.

"When a protein lands on the resonator, it causes a decrease in the frequency at which the resonator vibrates and the frequency shift is proportional to the mass of the protein," said Naik.

The researchers used the instrument to test a sample of the protein bovine serum albumin (BSA), which is known to have a mass of 66 kilodaltons.

The scientists are hopeful that the new technique could enable mass spectra for complicated mixtures to be built up, molecule-by molecule.

Eventually, researchers are planning to create arrays of perhaps hundreds of thousands of the NEMS mass spectrometers, working in parallel, which could determine the masses of hundreds of thousands of molecules "in an instant," said Naik.

The study has been published in the latest issue of the journal Nature Nanotechnology. (ANI)

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