Biopsies on Living Cells Using Nano-Tweezers


Tweezers with a tip less than 50 nanometres (0.0000005m) have been used to extract single molecules from living cells without destroying them.
Prior to this, examining cellular contents required homogenenation, centrifugation and a complex staining process, all of which had a chance to introduce artefacts, and hide the true nature of the cell. This method also only provided the cellular makeup at the time of its death (i.e. when it was about to be homogenised).
Using the nanotweezers to remove single molecules or organelles from individual cells whilst they are still alive, without damaging them, can provide us with vital information about insights into how healthy cells truly function, what happens when a cell becomes infected and more in depth analysis into cancer.

How Do They Work?

By using a technique called "dielectrophoresis",  polarisable particles can be attracted to a non uniform AC electric field.

At the end of the tweezer are two electrodes made from the carbon allotrope graphite. The electrodes have a gap of between 10 and 20 nanometres between them. By applying an alternating voltage, the gap creates a powerful electric field which can suspend and consequently extract small cellular components e.g. regions of DNA, mitochondrion, RNA etc.

The fact that they can fully extract the component out is what separates nano-tweezers from any 'alternative ' technology such as optical tweezers, which can manipulate cells but cannot extract.

Significance / Application

 Professor Joshua Edel, a pioneering chemist from Imperial whom this innovation is accredited to, and his colleagues have already extracted DNA from the nuclei of bone cancer cells in humans. Trapped DNA can be sequenced and analysed for any mismatches at a molecular level. These mismatches can be attributed to mutations that cause specific cancers. This lays down the base-principles off of which further research can be conducted in what exactly causes these mutations.

He has also successfully extracted a mitochondrion from a mouse's axon. Nerve cells require large amounts of energy to transmit impulses around the body, so they have a large number of mitochondria. By removing mitochondria from individual nerve cells, you can better determine their actual role in them, as well as modelling what happens with mitochondria (or the absence of it) in neurodegenerative diseases such Freidrich's Ataxia (uncontrollable movements of muscles due to production of the protein frataxin) The video below is from Joshua Edel's YouTube, showing the procedure using a  luminescent  dye covering neurons in the mouse. [ https://www.youtube.com/channel/UChuiBxtQC3utrZhhb0PzieA ]



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