Do live broadcasts in cells? Scientists took out a quantum microscope made of diamonds
Release date: 2017-04-12
A diamond-based imaging system that uses electron magnetic resonance to detect charged atoms and observe chemical reactions in real time.
The new microscope is capable of providing quantum magnetic resonance images of copper ions. David Simpson/University of Melbourne
Through probes made of diamonds, quantum microscopes can help researchers study the mysteries of the nanoscale microcosm, such as how DNA folds inside cells, how drugs work, and how bacteria metabolize metals. Crucially, quantum microscopy can image ions in solution separately, revealing the biochemical reactions that are taking place without interfering with the reaction process. On February 14th, a team working on this system published a preprint on the ArXiv server to illustrate their findings.
Just as medical magnetic resonance imaging (MRI) devices can reveal the internal structure of the human body without causing damage, similar imaging systems that can be used for molecular structures have always been the yearning for researchers. The goal of quantum magnetic resonance imaging, which uses quantum spins to form quantum-scale imaging, is to image chemical reactions, including chemical reactions involving metal ions. Existing magnetic resonance imaging techniques can only exhibit structures of 10 microns or more. The only way to detect metal ions in a cell is to add chemicals that can react with it, or freeze the cells so that they can be imaged under a high power microscope – all of which kill the cells.
The principle of medical magnetic resonance equipment is: placing the patient in a magnetic field, the protons of the atoms in the human body will be aligned with the magnetic lines of the magnetic field in the device; then the device emits a radio frequency pulse to the imaged area of ​​the human body, so that the protons are out of alignment; when the pulse ends The protons realign and release electromagnetic waves of a specific frequency; if the electromagnetic wave frequency released by the human tissue coincides with the frequency of the detector in the device, the two frequencies will resonate, just like the guitar strings of the same tone; such devices utilize This resonance reconstructs the human body image.
At the University of Melbourne, Australia, a team led by physicists Lloyd Hollenberg and David Simpson hopes to detect metal ions in cells through this technique. Some metal ions are harmful to cells, while others are required for biochemical reactions, such as metal ions involved in metabolism. The problem is that the NMR probe needs to be roughly the same size as the object to be imaged. For the observation of a single atom, this requirement is currently not met.
Defective diamond
To build quantum magnetic resonance microscopy, researchers used diamonds with a width of 2 mm and atomic defects in the crystal. These defects are sensitive to changes in the magnetic field and can be "frequency modulated" to resonate with the spin of the molecule or ion to be tested. When a defect in a diamond is illuminated by a green laser, the diamond emits red fluorescence and the intensity of the fluorescence depends on the strength and direction of the magnetic field.
The diamonds used by Hollenberg, Simpson, and colleagues have an array of defects near a specific location on the surface of the microscope that is placed next to the end of the microscope to be observed. They modulate the response frequency of the defect to a spin resonance that can be associated with copper ions (Cu2+) missing two electrons. When the diamond probe is exposed to a surface containing a sample of copper ions, the frequency resonance generated between the two excites fluorescence at the defect of the diamond. They then used a computer program to detect the color of the fluorescence at the diamond defect and reconstructed the image of the sample to locate the exact location of each copper ion.
Next, the researchers dipped the sample with an acid solution to cause the divalent copper ion (Cu2+) to acquire an electron and reduce it to a monovalent copper ion (Cu+.). They imaged the sample while applying acid, and it was observed that the spin image of the divalent copper ion gradually disappeared. Subsequently, during the one hour of exposure of the sample to the air, the monovalent copper ions were again oxidized to divalent copper ions, and the original image gradually reappeared. This method will one day help researchers to observe biochemical reactions occurring in cells in real time.
The kangaroo in the above figure was fabricated by a quantum magnetic resonance imaging microscope to detect copper ions (Cu2+) in a solution attached to the test template, wherein the developed area formed a pattern. (Scale bar represents 10 microns) David Simpson/University of Melbourne
Because of the non-intrusive nature of this approach, it is theoretically possible to image the interior of living cells – this is the direction of the team efforts of Simpson and Hollenberg. The core difficulty is that the diamond probe is close enough to the sample to generate a signal. But the team believes that the current approach is still helpful in understanding the mechanism of action of drugs and studying proteins on cell membranes. Researchers are also working to make this system suitable for detecting all types of metallic substances, including iron.
The physicist Friedemann Reinhard of the Technical University of Munich in Germany praised the results. “Their innovations have dramatically shortened the distance between this technology and the actual application,†he said. His team is also working with diamond microscopes, with the goal of constructing a system that can image 3D molecules.
He added that although the new technology still needs improvement, such as searching for copper ions in low-concentration solutions, it "has definitely taken a big step forward."
The original title is based on Quantum microscope offers MRI for molecules
Published on the "Nature" news on March 6, 2017
Original author: Sara Reardon
Source: Nature Natural Science Research (micro signal macmillan-nature)
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