A revolutionary method for weighing a single molecule

A microscopic instrument, 1000 times smaller than the thickness of a single hair, uses vibrational oscillations in order to simultaneously identify both the mass and the structure of a single molecule - a mechanism that did not exist until now.

[Translation by Dr. Nachmani Moshe]
Scientists have succeeded in developing a revolutionary new technology capable of simulating and weighing a single molecule and immediately identifying an individual virus.

A microscopic instrument, 1000 times smaller than the thickness of a single hair, uses vibrational oscillations in order to simultaneously identify both the mass and the structure of a single molecule - a mechanism that did not exist until now. The research was led by Professor John Sader from the University of Melbourne and Professor Michael Roukes from the California Institute of Technology. The research findings have long been published in the scientific journal Nature Nanotechnology.

The researchers note that this innovative method will revolutionize the field of molecular detection for biologists, or any other researcher interested in measuring extremely tiny objects. In order to identify the structure of the examined bone, the researchers connect it to a tiny oscillating device known as a resonator based on a nanoelectromechanical system (NEMS). "One common method to differentiate between different molecules is to weigh them using a process called mass spectrometry. The problem is that different molecules may have the same weight. Now, we are able to differentiate between them with the help of their shape recognition," says the lead researcher. This method is based on a new mathematical algorithm that we developed called inertial imaging. It can be used as a diagnostic tool if you're trying, for example, to locate a virus or bacteria."

In the method of mass microscopy, molecules undergo ionization (electrical charge) and thus an electromagnetic field can react with them. These interactions are then measured and essential information is obtained as to the mass/charge ratio of the molecule. However, this method is not able to distinguish between different molecules with identical mass/charge ratios. "However, when the molecule reaches an oscillating device of the NEMS type, it is possible to differentiate between their different masses. The frequency change of the device depends on the mass and shape of the molecule, so that many details can be learned about the structure and mass of the molecule," notes the lead researcher. "Our method is very different from optical microscopy where light limits the size that can be measured. In our method, this "light refraction limit" has no effect."

A common method for deciphering molecular structures is the use of X-ray crystallography. This complex method involves cleaning and forming the molecules, then exposing them to X-ray radiation and deciphering the resulting diffraction patterns. However, this method is also limited since the structure of a molecule in its natural environment may be different from its hard crystalline configuration. The researchers note that the new method could be extremely useful for biologists. "This new method adds another piece of information and helps to identify and decipher molecules, but now - at the single molecule level, a result that could be important in biomedical applications, among other fields."
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