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A logical extension
17 August 2009
DNA logic gates can now detect more than just DNA segments, and by exploiting nature's design, their preparation could be simpler than ever.
Atsushi Ogawa and Mizuo Maeda from The Institute of Physical and Chemical Research (RIKEN), Saitama, and Ehime University, Japan, have developed existing DNA logic gate systems to create a detection system where gold nanoparticle aggregation provides a visual marker for a variety of biomarkers.
Nanoscale logic gates can be made easily using aptazymes and nanoparticles
Logic gates are used in digital circuits in computer chips. An input signal goes through a binary operation to give either a true (one) or false (zero) output. This system has been mimicked in biology using DNA inputs, outputs and switches. DNA logic gates detect oligonucleotides (short DNA segments) when they bind to the logic gate sensors. This concept has been developed to detect different molecules using aptamers - DNA or RNA molecules adapted to bind to other molecules and viruses. However, both DNA and aptamer logic gates have a drawback in that they rely on a hybridisation switch. When a target molecule binds, or hybridises, to the sensor, the event has to be transmitted to a reporter system, which must be specifically engineered for each sensor-target system.
- Milan Stojanovic, Columbia University, New York, US
'We want to apply this method to construct more complex logic gates,' says Ogawa. 'Because the aggregation of gold nanoparticles depends on whether or not DNA on the nanoparticles forms a duplex with the cleaved RNA with a blunt end, we think an appropriate design of the cleaved RNA sequences may make them possible.'
Milan Stojanovic, an expert in diagnostic molecular devices based on nucleic acids, at Columbia University, New York, US, says that the work is an 'important contribution' towards a field that 'has a future if it moves in the direction of autonomous therapeutic devices, rather than towards competing with silicon.'
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Link to journal article
Easy design of logic gates based on aptazymes and noncrosslinking gold nanoparticle aggregation
Atsushi Ogawa and Mizuo Maeda, Chem. Commun., 2009, 4666
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