This achievement was published today in the scientific journal NATURE, and was presented at a prestigious scientific conference held in Brussels with the participation of Nobel laureates, which focuses on visionary development directions in the fields of life sciences and medicine
Weizmann Institute scientists have developed a molecular biological computer that detects conditions typical of cancer in a test tube, diagnoses the type of cancer and produces a suitable drug molecule in response
The molecular biological calculation system, the smallest in the world according to the 2004 edition of the Guinness Book of World Records, is moving from a stage of simple calculations to the field for which it was originally intended: now it is able to identify - in vitro - biological molecules that represent conditions typical of certain cancers, diagnose the type of cancer and respond by producing molecules appropriate medicine.
In 2001, Prof. Ehud Shapira from the Department of Computer Science and Applied Mathematics and the Department of Biological Chemistry at the Weizmann Institute of Science, and his research colleagues, presented a molecular biological calculation system capable of performing simple calculations. The input, output and "software" of the system were made of DNA molecules, the genetic material. Its "hardware" was composed of two enzymes ("molecular machines") that perform cutting and gluing operations of DNA molecules. When these molecules are given together in solution, the hardware and software molecules work together, in coordination, on the input molecules and produce the output molecule. This molecular calculation system can be programmed by selecting different "software" molecules that will determine how the system will operate. In certain programming, for example, this system can check whether in an input molecule encoding a list of digits 0 and 1, all occurrences of 0 precede all occurrences of 1. In 2003, the team introduced another version of the computer, which uses the input molecule also as the computer's energy source.
This computer is the basis of a new study by Prof. Shapira and his team, research students Yaakov Benanson, Benjamin Gil and Uri Ben-Dor, and Dr. Rivka Ader, from the Weizmann Institute of Science, which is published today in the scientific journal NATURE, and which was presented at the Life, a Nobel Story conference in Brussels. In this study, an input mechanism was added to the computer, which allows it to identify certain biological molecules (mRNA), changes in their amount compared to their normal amount in the cell are a marker for certain types of cancer. An output mechanism was also added to the computer, which allows it to release in response, in a controlled manner, a single-stranded DNA molecule intended to cause the death of the cancer cell (the experiment that the scientists reject was carried out in a test tube, but in the future they hope to activate the system in cell tissues).
For example, in one series of experiments, the scientists were able to program the computer to recognize the presence of mRNA molecules that carry the code to create certain proteins whose overexpression is characteristic of prostate cancer cells. The computer that recognizes these conditions and diagnoses prostate cancer in response produces a single-stranded DNA molecule whose presence in the cell causes the cancer cell to "suicide". In a similar way, the scientists were able to diagnose - in vitro - also the conditions characteristic of tumors of a certain type of lung cancer (SCLC).
Prof. Shapira: "Our vision for the future is that biomolecular computers will operate within the tissue of living cells, recognize characteristics of diseases ahead of time, diagnose the disease and respond immediately by producing a drug that will curb the disease that was diagnosed while it is still in progress. It is clear to all of us that the road to realizing the vision is very long, and it may take decades before such a computer can operate in the human body. At the same time, about two years ago I estimated that it would take at least ten years until we reach the results we presented today."
A cubic meter contains more information than a trillion CDs
Computers made of DNA have been produced in the past, but for their operation a series of arduous operations were required, and the assistance of humans. The previous molecular computers "were basically computers the size of a room," Prof. Shapira told "Haaretz" before leaving for a conference in Brussels, and after the publication of the article that revealed the biological computer developed at the Weizmann Institute. Shapira and his team were looking for a scientific-medical application for the nanocomputer they developed that could take advantage of its basic feature - it is made of molecules and therefore can communicate with other molecules.
While the development of silicon-based chips is approaching the limit of miniaturization, the biological computer is so small that millions of computers can be crowded into a single drop, and perform a billion operations in a second. In one cubic centimeter, more information can be compressed than in a trillion computer CDs.
The biological computer developed by the institute requires only the correct molecular mixture, and performs all the computational operations by itself. The computer's hardware is made of enzymes, which paste and cut the DNA. When the DNA and enzymes are mixed together they can perform calculations with an accuracy of 99.8% and more per calculation operation. Prof. Shapira admitted that he was surprised by the results of the experiment. "Sometimes science provides pleasant surprises and not just disappointments", he says with a smile.
When asked what his plans are for the future, he replied: "Rest." We worked hard on the experiment and the article for the journal." After the rest, the scientists plan to refine and improve each of the various components of the biological computer they developed. "Since our computer is modular, it is possible to improve each component separately: the input component, the calculation component and the output component. For example, you can think of other types of drugs that will be used as the output of the computer. The main challenge, which is still not clear to us how we will overcome it, is how to integrate the computer into a living environment."
To Prof. Ehud Shapira's website
For the article in Nature (PDF format
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