Sphere of radiance: glowing biochips will detect diseases in the traces of molecules

Scientists at ITMO University have developed devices that, in the future, will quickly identify biomarkers of several diseases in a single blood sample, from cancer and cardiovascular to infectious, and will be able to detect even extremely small concentrations of the necessary molecules. We are talking about optical microresonators, which can become the basis for a new generation of ultra-sensitive biochips. They emit light and independently amplify it hundreds of times. Among other things, such structures will be useful as miniature tags for protection against counterfeiting and labeling systems, including for the needs of microelectronics.

Why do we need optical microresonators?

Researchers from ITMO University have created optical microresonators for medical diagnostics that not only hold and amplify light, but also generate it themselves. As the scientists explained, these miniature devices can be compared to a round mirrored room in which a ray of light is reflected from the walls over and over again, which makes it much more intense. Due to this property, such "amplifiers" can be used to create miniature lasers, biomedical sensors and optical tags to protect jewelry from counterfeiting.

However, microresonators are not widely used yet, since most of the existing samples have serious disadvantages: they have to be "activated" with a powerful laser, otherwise they simply will not retain and amplify light. In addition, the materials from which such devices are made are often incompatible with biological objects, which does not allow them to be used in medical diagnostics.

The authors used standard microresonators — spheres made of polystyrene with a diameter of about five micrometers (ten times thinner than a human hair). Phosphors (luminous particles) of two types were placed on their surface: nanocrystals consisting of silver, indium and sulfur, as well as carbon dots.

The researchers then applied two additional layers of polymer and gold nanoparticles. The first one served as an insulator — it prevented the gold from interacting with the underlying nanocrystals and extinguishing their glow. The gold served as an "antenna" that amplifies the light emitted by the microresonator.

Scientists have also created a material that is more than 10 thousand This increases the sensitivity of Raman spectroscopy, a method for analyzing the composition of a wide variety of mixtures. Thanks to the development, this approach will be able to be used to detect even minimal concentrations of molecules of interest in complex media such as blood, reservoirs, refined petroleum products, and others.

— In the future, we plan to combine the research carried out earlier and, based on these results, create a "laboratory on a chip" type structure with the possibility of parallel detection. We will also analyze the stability of hybrid structures in liquid media, their response to complex multicomponent samples, and determine detection limits and selectivity on model compounds for various microsphere architectures," said Kirill Bogdanov, project manager, head of the laboratory at the International Scientific and Educational Center for Physics of Nanostructures at ITMO University.

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Prospects for the creation of biochips

The technology opens up great prospects for the creation of ultra-sensitive express diagnostic biochips, Vadim Kovalyuk, head of the Laboratory of Photonic Gas Sensors at NUST MISIS, told Izvestia.

— The next challenge on the way to commercialization will be the stabilization of architecture in real biological environments, where protein sticking and pH fluctuations can distort the geometry of spheres and reduce the reproducibility of signals. Nevertheless, the high flexibility of the proposed method gives every reason to believe that these technological barriers will be successfully overcome, providing a breakthrough in the availability of early diagnosis of various diseases.

Such luminescent microresonators look like a very promising platform for diagnostic medicine. It is logical to integrate sensors into liquid biopsy systems, portable express analyzers, and laboratory multiplex platforms capable of simultaneously tracking several markers in one sample, said Marina Chumakova, a leading market expert at NTI Healthnet.

"From the point of view of specific nosologies, this technology may be useful in oncological, cardiovascular diseases and in the diagnosis of infectious diseases, where the speed and accuracy of detection of antigens or antibodies are important," the specialist told Izvestia.

The results of the study, supported by a grant from the Russian Science Foundation (RSF), are published in the journal Optics and Laser Technology.