Nanoparticles and viruses on the smartphone screen
Smartphone turns into a fluorescent microscope
ChemPort.Ru based on the materials of the University of California at Los Angeles:
UCLA researchers' smartphone 'microscope' can detect a single virus, nanoparticlesResearchers have developed a new lightweight device that, when attached to a smartphone, with a slight movement of the hand allows you to turn the phone into a sensitive fluorescent microscope.
An additional attachment allows you to use a smartphone camera to obtain images of individual nanoparticles and viruses, which, in the future, can be used to diagnose various kinds of diseases in developing countries or areas with underdeveloped medical infrastructure.
Fluorescent microscopes can detect and study important biomolecules or individual cells if fluorescent tags are inserted into them. However, as noted by Aydogan Ozcan from the University of California, fluorescence microscopes are bulky and expensive devices, as a result of which, in conditions of limited resources and funds, it is very difficult to have access to these important diagnostic tools.
Ozkan decided to create a portable fluorescent microscope using a device compatible and used in conjunction with a smartphone camera – smartphones are small in size, not particularly expensive (compared to fluorescent microscopes), cellular networks are triumphantly conquering more and more new territories of the globe, many people have a personal smartphone (and more than one). However, detecting and generating the image of nanoparticles and viruses is not an easy task, since individual particles labeled with a fluorescent dye emit a very weak emission signal, especially in comparison with other light sources in the experiment, such as laser radiation exciting a fluorescent dye.
Researchers from the Ozkan group solved a difficult problem by developing a compact system of lenses and filters that can remove background noise caused by laser radiation. To begin with, they optimized the way in which light falls on a sample located on a cover glass located above the camera of a mobile device. The researchers positioned the laser diode so that it illuminated the sample at an angle of 15 degrees relative to the plane of the glass with the sample. Falling at this angle, most of the radiation from a light source with a wavelength of 450 nm does not fall into the camera lens, which registers the fluorescent signal from the dye. The system was also supplemented with a filter that transmits in the long-wavelength region of the spectrum, which made it possible to cut off the laser radiation scattered by the sample. Thus, only the emission radiation emitted by the fluorescent label falls on the camera lens of the mobile device and on the camera sensor.
To test the capabilities of their portable fluorescent microscope, researchers from the Ozkan group studied human cytomegalovirus particles containing fluorescent tags, ranging in size from 150 to 300 nm and polystyrene beads with a radius of about 100 nm. The last nanoparticles were the smallest that the new device could detect. The researchers used the scanning electron microscopy method to independently confirm the position and size of the studied particles and showed that the results obtained using the direct method are consistent with the results obtained using a smartphone – a fluorescent microscope.
According to Ozkan, the device developed in his group is the first example of a portable, smartphone-compatible system for detecting individual viruses and nanoparticles. To commercialize this and other analytical techniques based on the use of cell phones, Ozkan created the Holomic company. His group has also developed a number of mobile applications for data analysis.
Article by Wei et al. Fluorescent Imaging of Single Nanoparticles and Viruses on a Smart Phone is published in the journal ACS Nano.
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