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Сalculations with Nanoscale Smart Particles
Researchers from the Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Institute of General Physics of the Russian Academy of Sciences, and Moscow Institute of Physics and Technology have made an important step towards creating medical nanorobots. They discovered a way of enabling nano- and microparticles to produce logical calculations using a variety of biochemical reactions. Details of their research project are given in the journal Nature Nanotechnology.
The paper draws on the idea of computing using biomolecules. In electronic circuits, for instance, logical connectives use current or voltage (if there is voltage, the result is 1, if there is none, it’s 0). In biochemical systems, the result can be, for example, production of a given substance or induction of a certain biomedical response from a living system. For example, modern bioengineering techniques allow for making a cell illuminate with different colors or even programming it to die, linking the initiation of apoptosis to the result of binary operations.
Many scientists believe logical operations inside cells or in artificial biomolecular systems to be a way of controlling biological processes and creating full-fledged micro-and nano-robots, which will be able, for example, to deliver drugs on schedule to those tissues where they are needed.
Calculations using biomolecules, a.k.a. biocomputing, are a very promising and rapidly developing branch of science, according to the leading author of the study, Maxim Nikitin, a recent MIPT Ph.D. graduate and a Research Associate at the Institute of Bioorganic Chemistry and General Physics Institute. For biocomputing within cells, it is possible to use natural cellular mechanisms. It is far more difficult, however, to do calculations outside cells, where there are no natural structures that could help carry out calculations. The new study focuses specifically on extracellular biocomputing.
The study paves the way for a number of biomedical technologies and differs significantly from previous works in biocomputing, which focus on both the outside and inside of cells. Scientists from across the globe have been researching binary operations in DNA, RNA and proteins for over a decade now, but Maxim Nikitin and his colleagues were the first to propose and experimentally confirm a method to transform almost any type of nanoparticle or microparticle into autonomous biocomputing structures that are capable of implementing a functionally complete set of Boolean logic gates (YES, NOT, AND and OR) and binding to a target (such as a cell) as result of a computation. This method allows for selective binding to target cells, as well as it represents a new platform to analyze blood and other biological materials.
Nanoparticles were coated with a special layer, which “disintegrated” in different ways when exposed to different combinations of signals. A signal here is the interaction of nanoparticles with a particular substance. For example, to implement the logical operation “AND” a spherical nanoparticle was coated with a layer of molecules, which held a layer of spheres of a smaller diameter around it. The molecules holding the outer shell were of two types, each type reacting only to a particular signal; when in contact with two different substances small spheres separated from the surface of a nanoparticle of a larger diameter. Removing the outer layer exposed the active parts of the inner particle, and it was then able to interact with its target. Thus, the team obtained one signal in response to two signals.
Conceptual designs of biocomputing structures for YES/NOT/AND/OR logic basis. Figure is modified from Nat. Nanotechnol.
For bonding nanoparticles, the researchers selected antibodies. These natural proteins of the immune system have a small active region, which responds only to certain molecules; the body uses the high selectivity of antibodies to recognize and neutralize bacteria and other pathogens. Remarkably, the reported concept is the first to allow computation of any logic function without relying on the use of DNA or RNA.
Making sure that the combination of different types of nanoparticles and antibodies makes it possible to implement various kinds of logical operations, the researchers showed that cancer cells can be specifically targeted as well. The team obtained not simply nanoparticles that can bind to certain types of cells, but particles that look for target cells when specific conditions on concentration of ambient molecules are met. This additional control may come in handy for more accurate destruction of cancer cells with minimal impact on healthy tissues and organs.
Maxim Nikitin said that although this is just a small step towards creating efficient nanobiorobots, this area of science is very interesting and opens up great vistas for further research, if one draws an analogy between the first works in the creation of nanobiocomputers and the creation of the first diodes and transistors, which resulted in the rapid development of electronic computers.
The new work was published on the website of the journal Nature Nanotechnology, one of the most authoritative scientific publications in the world.
This press release was initially published at MIPT website.
august 21, 2014
Source: http://www.nature.com/nnano/journal/vaop/ncurrent/full/nnano.2014.156.html