Rapid extraction of nucleic acids for quick diagnosis

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Nucleic acids have several practical applications in Analytical Sciences as they can be used as biorecognition molecules (e.g. aptamer) in the design of sensors and even extraction phases. However, this post deals with those methods that are aimed to determining nucleic acids in samples of different origin (usually biosamples). Among these applications, we can highlight paternity tests, the study of genetic diseases, the identification of the virus or bacteria behind an infection or the certification of the origin of a meat in a processed food.

Whatever the application is. the extraction of nucleic acids of the system under study is the initial (and usually) critical step. The conventional extraction procedure, which is based on the use of silica particles as extractant, involves several steps like extraction or clean-up that makes the process tedious, especially if we consider that the particles should be separated from the sample or washing solutions by centrifugation. The use of magnetic nanoparticles can simplify the process (as the extractant can be easily recovered from the solution by an external magnet) but every step should be developed sequentially. In other words, the magnetic NPs should be dispersed into the solution and recovered several times in each protocol. In addition, the complete elimination of the sample adsorbed into the NPs is not an easy process.

Analytica Chimica Acta has recently published a novel procedure that tries to overcome all these limitations. In this article, colleagues from Japan have proposed a dedicated device that allows the extraction of nucleic acids in only 3 min. The device is clearly presented and discussed in the article but we will try to explain its main fundaments. The extraction is done using magnetic silica beads that are moved by two external magnets. These magnets have two general movements:
  • longitudinal, that allows the pass of the magnetic NPs through the sample and washing solutions (which are separated by silicone oil segments)
  • transversal, that permits the efficient dispersion of the NPs in each solution. This movement is possible by the alternative movement of both magnets at the opposite sides of the device.

The results are clearly remarkable. This extraction protocol combines with polymerase chain reaction (PCR) provides results in only 15 min and therefore it can be used for rapid diagnosis.

As this is just a brief excerpt you will find additional info in the original article whose reading is highly recommended. Among this info, we can highlight
  • The complete description of the system including the whole structure of the device which is fully automated.
  • The optimization of the protocol and its comparison with the manual one.
  • The combination of the extraction procedure with PCR for the detection of M. pneumoniae.


Reference:

(1) A novel automated device for rapid nucleic acid extraction utilizing a zigzag motion of magnetic silica beads. Link to the article

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