The 50th, jubilee International Exhibition of Inventions and Innovations ("Eureka-Brussels-2001") has awarded a Diploma and a Gold Medal to the R&D work "A Bioanalytical System for Determining Biologically Active Compounds".
This project is a product of joint involvement by the V.A. Engelgardt Institute of Molecular Biology of the Russian Academy of Sciences (Moscow), the Institute of Spectroscopy of the Russian Academy of Sciences (Troitsk, Moscow) and the Biochemistry Institute of the University of Munster (FRG). Our observer Arkady Maltsev has interviewed heads of the research teams that have cooperated in this project on the Russian side:
Dr. Yuri Yevdokimov, laboratory head at the Molecular Biology Institute, and Dr. Oleg Kompanets, deputy director of the Spectroscopy Institute. Here's a transcript of this interview.
- How do you explain such high recognition accorded to your work? What is it all about?
- Yu. Yevdokimov: Quite often in medical, biochemical or ecological studies it is essential to find out if there are biologically active or toxic compounds present in the human organism or in the environment. For instance, antibiotics, heavy metals, phosphoorganic and other genotoxicants, heparin, proteins and the like. Quite a few methods are in use now, such as liquid or gas chromatography, mass spectrometry, Spectroscopy and others, making it possible to determine the presence and concentration of corresponding agents with high accuracy. However, such analysis is a costly and laborious procedure. Equipment costs are high, and then you need high-skilled personnel who can do the job.
Our system, while performing the same functions (and much more!), has added advantages, for it is based on a novel principle, a world's first. Its centerpiece is an optical sensor which, in its turn, comprises a DNA liquid crystal biosensor and a portable optical analyzer, the dichrometer.
The biosensor (biologically sensitive element) is the heart of our system: it is an assembly of DNA molecules which "recognizes" definite substances in an analyzed sample and signals their presence through what we call a "primary" signal. Say, changes in the sample's mass and color, or some other parameters (optical, electrical and so forth) can
An outline of biosensor design.
elicit this signal. There are specific biosensors making it possible to "recognize" a certain compound at very high sensitivity down to several thousand molecules, and there are also "group assay" biosensors which can detect a set of substances (heavy metals, pesticides) in the sample. The dichrometer communicates an array of such data in a clear, user-friendly form.
Our setup can assay this or that medium within 10 to 20 minutes; this is a simple and low-cost analysis which does not involve high skills to do.
- But that's "the tip of an iceberg", so to speak. What about the hidden part of the biosensor and dichrometer? Could you specify?
- Yu. Yevdokimov: I'll take the first part of the question, and then my workmate will carry on.
That's how it all began. Our Institute's research team I was heading, with Doctor of Biology Sergei Skurdin, Master of Chemistry Viktor Salyanov, among others in it, had for a number of years been studying the physicochemical and biological properties of DNA in a "condensed state", characteristic of the heads of some viral particles, spermia, and so on, and also characteristic of protozoal chromosomes. Our results, essentially of basic science significance, proved interesting on the practical side too. We found such DNA molecules to persist in a liquid-crystal state; that is, on the one hand, they are fluid like any other liquid is and, on the other, are ordered in space like crystals. Furthermore, we found macroscopic liquid-crystal phases of DNA, as well as DNA microparticles having a different orderliness of molecules and thus differing in their characteristics, optical characteristics for one. Say, the spatially wound ("holesteric") phase of DNA exhibits optical activity* tens and hundreds of times as high as individual molecules do. Such activity is called therefore "anomalous".
Now why is this important? The point is that nitrogen bases (which are DNA structural elements persisting in an ordinary, not liquid- crystal state) interact with some chemical or biologically active compounds (antibiotics, antitumor drugs and the like) and form complexes possessing a number of specific characteristics, for one, the anomalous optical activity. This means that nitrogen bases can help us determine the presence of some groups of substances and thus can be regarded as sensitive elements.
Well, what is going to happen if we convert the DNA from its natural
* Optical activity-ability of some substances to cause rotation of the polarization plane of plane-polarized light passing through. - Ed .
state into a liquid-crystal one? Our experiments show: in this state, too, the ability to "recognize" corresponding groups of compounds is still there. In the course of further studies we found that each particle of DNA in a liquid-crystal holesteric state evolves as a miniature optical sensor (0.5 mkm in size) which changes its characteristics in the presence of biologically active compounds. More than that, making use of the orderly pattern of DNA molecules in this very phase, we learned to "insert" additional sensitive elements in between, capable of detecting concrete chemical compounds. That was our pioneering discovery.
Obtaining splendid results like that, we could have rested on our laurels in the realm of pure science theory. However, the ability of biologically active compounds, interacting with DNA molecules, to induce different changes in the optical characteristics of their liquid-crystal particles made us stop and ponder: why not use in practice this "recognition ability"? But for practical application of our findings we needed a device capable of registering changes in the biosensor's state (wavelength, amplitude and sign of anomalous optical activity) and putting out desired data in a user- friendly fashion. But this matter was beyond our scientific competence.
- And how did you cope ?
- Yu. Yevdokimov: We turned for advice to the Ministry of Science and Technologies of the Russian Federation (that's how this body was called then). It suggested that we enlist the RAS institute of Spectroscopy, well known for its opticospectral robots, for designing a device we needed.
- And how did the people there, at Troitsk near Moscow, respond to your request?
- O. Kompanets: It did not catch us unawares. Our previous record gave us hope enough. We were to design a spectrometer capable of registering an optical circular dichroism signal coming from the biosensor. In short, we were supposed to hand out a dichrometer.
This is a sophisticated device, no question. But it is composed of sev-
eral "simple" gadgets, each carrying out one particular function. Let's consider the principle and sequence of operations.
It all begins with the radiation source emitting the entire spectrum of visible and ultraviolet light. The beam first gets into a monochromator which, assisted by a diffraction grating, picks out one wavelength; thereupon it enters a polarizer, from where it comes plane-polarized; and last, this beam penetrates into a photoelastic modulator rotating its polarization plane in circle, now left, now right. The thus "seasoned" beam is fed through an assayed sample containing an unknown biologically active compound which, however, has already reacted with a dispersed liquid-crystal DNA (biosensor) and changed its optical properties. It is at this point that partial absorption of the light takes place- uneven for the left and the right "winding" of the polarization plane. This difference is called optical circular dichroism, which is registered by a photodetector at the end of the line of research instruments. It transforms the optical signal into an electrical one; next, with the aid of a personal computer, this information is flashed on the display.
The first model of the device was a makeshift affair, assembled as it was from standard blocks available at our laboratory. Rather awkward and odd, it gave correct results nonetheless. Making a portable dummy took a year during which we redesigned all the component units. A control testing of the system "liquid-crystal biosensor/portable dichrometer" showed its high efficiency in determining an antitumor compound in blood plasma. Subsequent experiments carried out jointly with research scientists of the Molecular Biology Institute proved the biosensor to be capable of detecting a range of compounds, from salts of heavy metals to antibiotics and proteins. The sensitivity of the system depends on the nature and characteristics of particular substances and is within 10 -7 -10 -14 mole. Considering all these characteristics, our biosensor has a good chance of finding application in various industries, in farming, medicine and ecoactivities, that is wherever it is important to detect - and do it fast - low concentrations of genotoxicants, the substances affecting cell genetics.
Our dummy, imperfect as it was, showed it abundantly clear: we designed an absolutely new bioanalytical system of great practical value. Our designs, including those of the biosensors based on DNA liquid-crystal dispersion and designs of the dichrometer, were awarded Russian Federation's patents for inventions in 1998, with priority as of 1996.
- You have won recognition here in Russia. But what's the attitude of your counterparts abroad?
- O. Kompanets: They saw the significance of our setup fast. And they were showing vivid interest. We had to patent our biosensor abroad so as to protect the Russian priority. Our research centers could not afford such a costly procedure though. But here the RAS Commission on Foreign Patenting, which Academician Yevgeny Dianov is heading, helped us out. Having registered our brainchild in the United States, Great Britain, Germany and Italy we could have had no worries in developing our dummy to a prototype and then to an industrial prototype; but again, we were stymied by that "damned" money problem.
- Yu. Yevdokimov: What helped us over the hump was that the international project Biosensors was still on. And so our two research institutes signed an agreement with the University of Miinster, Federal Germany, on developing a new model of our system. This agreement provided not only for participation of German scientists but also for allocation of funds from the FRG Science Ministry.
We managed to accomplish a good deal in those two years, between 1997 and 1999. In particular, we designed various types of new biosensors, some of them jointly with our colleagues from Germany, Italy and Britain.
- O. Kompanets: In addition, we made a new improved model of the device and enhanced the sensitivity and speed of proximate analysis. But that's not all. Our dichrometer, we found out, can be used independently in various studies. Its mass, its cost and operational expenses are actually a tenth of what foreign analogs are having.
- Did you send the final model of у our setup to Brussels?
- O. Kompanets: In 1999 our agreement with the Germans expired, and we found ourselves in low water again. But at the turn of the years 2000 and 2001 the Russian investment company Leading became interested in our work. This interest stemmed not only from the very fact of our patents-our system offered a broad range of applications in a variety of fields: in clinical biochemistry, pharmaceutics, biotechnology, ecology and so forth. Thanks to financial backing from this company we founded a joint company OOO Bioanalytical Technologies, where we "debugged" our device. Then we displayed it at the Eureka-Brussels exhibit and won a Diploma and a Gold Medal.
Let me add in conclusion: the RAS experimental plant of research instrument making (based at Chernogolovka near Moscow) plans to turn out a batch of 20 biosensor dichrometers in 2002.
Prepared by A. MALTSEV
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