The biosensor will detect the infection
Russian scientists have developed an optical biosensor that will diagnose infectious diseases in seconds. The device is capable of detecting bacteria and viruses using infrared light and can be widely used in large transport hubs, for example, at airports, where constant monitoring of the infectious situation is required in conditions of large human flows.
The sensor is a silver nanofilm with many micro-holes deposited on a transparent substrate made of the natural mineral fluorite. A sample of biomaterial is placed on the film, for example, scraping from the nasal mucosa. Then the surface with the biomaterial is illuminated in an infrared spectrometer. By the spectrum of light that has passed through the sample, it is already judged on the presence of bacteria or viruses in it. In the work, scientists used the Staphylococcus aureus bacterium to show that with the help of a biosensor, pathogenic microorganisms can be quickly detected.
This method of express analysis is useful in transport hubs where continuous monitoring of the health status of a large number of people is required. Now thermal imagers are being installed for these purposes, which monitor the temperature of passengers. If the device shows that a person's temperature is elevated, then a potential source of infection has been detected. In this case, a clarifying analysis is needed, which will tell you whether the passenger is really sick and what exactly. Analysis of the biomaterial for bacteria and viruses using existing methods, such as polymerase chain reaction, will take several days. While the new methodology of Russian scientists allows you to get results immediately.
Scientists from ITMO University, the National Research Nuclear University "MEPhI", the Lebedev Physical Institute of the Russian Academy of Sciences and the Moscow Institute of Physics and Technology participated in the development of the biosensor. The study was conducted in close cooperation with Infectious Diseases Clinical Hospital No. 2 in Moscow.
Another advantage of the biosensor is its sensitivity. Sergey Kudryashov, a leading researcher at the Department of Laser Technologies and Laser Technology at ITMO University and the FIAN Gas Laser Laboratory, says: "Optical biosensors made using our technology can detect even very small amounts of bacteria. Thus, early highly sensitive diagnostics of infectious diseases in kindergartens, schools and universities, especially during periods of seasonal epidemics, will reduce treatment to prevention. This technique will help doctors in infectious diseases hospitals to diagnose patients more quickly."
The high sensitivity is due to the lattice structure of the silver layer. When infrared waves pass through the biosensor, the incident light is redistributed on its surface. Micro–holes turn into so-called "hot spots" - zones with the highest intensity of light. The biomaterial fills the holes, and the bacteria fall entirely into these zones. Bacteria more actively absorb light in "hot spots", which increases the likelihood of detecting pathogens.
Infrared spectra of the transmittance of the sensor element and a simple silver film (for comparison) with the applied culture of Staphylococcus aureus
Scientists managed to cut microscopic holes in the film using a special laser that emits millions of pulses per second. Thanks to him, specialists managed to automate and noticeably speed up the process of creating a silver lattice.
The methods of optical biosensor analysis are not new, but they are still poorly implemented. This is due to the fact that technology did not allow making real prototypes of devices that could be tested in laboratory and clinical practice. Therefore, researchers are faced with another large–scale task that needs to be solved before the introduction of a new platform into everyday use - this is the creation of reference databases with which the readings of the infrared spectrometer could be compared.
The readings of spectrometers are always compared with the library of signals characteristic of certain groups of molecules. Any microorganism can be detected by the optical activity of its specific components. For example, Staphylococcus aureus is given carotenoids – derivatives of carotene, which turns carrots orange.
Scientists hope that in the future their development will find wide application due to the cheapness and speed of manufacturing sensors, as well as the use of more common materials for substrates. In addition, by calibrating the spectrum libraries, it will be possible to determine not only the type of bacteria or virus, but also their number.
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13.10.2016