"Load driver" for a biocomputer
Bio-logic circuits
Cybergenetics have learned to reliably transmit signals
between different components of a biocomputerAlexander Telishev, "Russian Planet"
Scientists write about the prospects of using such biocomputers in the journal Nature Biotechnology (Mishra et al., A load driver device for engineering modularity in biological networks – VM).
"We are currently working on the creation of biosensors – cells that can recognize a specific set of molecules in the environment and respond to them in a special way. For example, such "live" computers will be able to find hormones and proteins that signal the presence of cancer cells nearby, and in response to this signal begin to produce molecules that destroy the tumor," says bioengineer Domitilla del Vecchio from the Massachusetts Institute of Technology.
Figure from the MIT press release New device could make large biological circuits practical – VM.
Del Vecchio and several other engineers, computer scientists and geneticists of the Institute have been working for several years to create a special genetic device, which they call a "load driver" by analogy with one of the important components of classical electronic devices. Such devices are not an integral part of logic circuits by themselves – they only help them work correctly, neutralizing parasitic currents and stabilizing the operation of transistors.
The biological analogue of the "load driver", as the authors of the article note, is vital for the further development of bioelectronics. Research in this field of knowledge at the junction of microelectronics and molecular biology has been conducted since the beginning of the twentieth century. Already in 1994, scientists were able to create a logical scheme from DNA that coped with choosing the optimal path through many points on the map, provided they intersect only once (the Hamiltonian graph problem in the language of mathematics).
At the beginning of this century, biotechnologists managed to create biological analogues of the simplest elements of computers – chains of proteins and related genes that can perform logical operations: "AND", "NOT", "OR" and perform the simplest calculations. Back in 2007, one of the authors of the article, Ron Weiss, was able to turn human kidney cells into the simplest biocomputer, and in 2011 his British colleagues taught E. coli the basics of "arithmetic".
At this point, progress in the design of "biological" elements stopped abruptly – with the complication of the number of protein or DNA transistors and the number of connections between them, the efficiency of the entire biocomputer decreases sharply. According to scientists, this problem is primarily related to how information is transmitted and processed in biocomputers.
Transistors in conventional silicon chips are almost completely isolated from the outside world and exchange information with each other through separate channels – metal tracks and wires. Their biological "cousins" do not have such luxury – they are part of a living organism and share a common space with each other and with other cell systems that do not participate in calculations.
The "communal" nature of biocomputers creates two big problems. It is extremely difficult to increase their power, since when each new transistor appears in the logic circuit, scientists have to add another set of signal molecules to the biocomputer, which will allow it to communicate with other components.
The second problem is that these signals are not as unambiguous as current pulses in conventional transistors – in biological systems, in addition to the usual "on", "off" modes, there is also a "maybe" option. This is due to the fact that protein and RNA molecules, which play the role of signal carriers, move through the cell rather slowly, and not instantly, like electrons along paths in electronics, and often fall into the wrong parts of the cell where they should be.
The reverse signal of the work done coming from the second transistor back to the first one often reaches it before it completes the transmission of information, which further increases the chaos and ambiguity. As a result, biocomputers almost always have a small number of extra signaling molecules, which, like parasitic currents in conventional electronics, interfere with their correct operation.
Del Vecchio and her colleagues in the laboratory solved this problem – in fact, they created a biological analog of a signal buffer that gradually accumulates molecules and releases them only when it becomes unambiguously clear that one biotransistor transmits to another. The secret of the operation of this biological device, the "load driver" in their terminology, is that it reacts to signaling molecules much faster than the elements of logic circuits themselves. This allows it to suppress "parasitic currents" and make signal transmission almost as reliable as in conventional silicon electronics.
Such biological schemes, in their opinion, will be used for the most part for medical purposes. In addition to fighting cancerous tumors, they can help diabetics get rid of the need to take insulin regularly. Scientists from the Massachusetts Institute of Technology plan to create a biological computer that will monitor blood sugar levels and secrete the hormone when it exceeds the normal mark.
As the authors of the article emphasize, one should not expect the appearance of super–complex biocomputers on store shelves in the near future - it will take many more years to finalize the technology and eliminate all "childhood diseases", as in the case of conventional silicon microchips.
Portal "Eternal youth" http://vechnayamolodost.ru25.11.2014