Xenon – the miracle molecule

Xenon is one of the so-called noble gases. Noble gases are the chemical equivalent of a teenage kid quietly sitting in its room and not saying much in the school cafeteria, while its friends go party like there’s no tomorrow, and then grows up to be the most promising Student Government President and an amazing scientist. Under normal conditions they are very stable, reacting very little with other chemicals, and having little to no color and odor. Xenon was discovered in 1898 and since then it’s been slowly but surely making its way in our lives in more and more areas.

Originally, xenon was used only in optics for lamps and lasers.

 

Most of you have seen xenon front-lights of a car – those very bright lights that poke the eyes out of their sockets when someone is tailing you during a night drive.

But for me, much more interesting are the biological applications of xenon. It is making its way into medicine as a general anesthetic. Turns out it competitively binds to several types of receptors in the brain, and additionally, it inhibits a potassium channel, but activates a calcium exchange enzymes which are both responsible for the synaptic activity¹. It turns out that xenon as a gas to put you under doesn’t have many of the unpleasant side effects of standard anesthetics – for example doesn’t make you nauseous and does not cause vomiting.

Scientist dug deeper into this receptor inhibition by xenon occurring in the brain because as it turns out, in many diseases or pathological conditions receptors get over-activated and to put it mildly start firing non-stop, which leads to an incredibly fast exhaustion of the neurons, their death and the decay of the whole organism. It appears that due to the ability of xenon to counteract the over-activation of some receptors and to sustain the activity of certain enzymes, it serves as a very good supplement to drugs aimed at neuroprotection during accidental and chronic brain traumas (ischemia, injuries, ALS, Parkinson’s and Alzheimer’s). So far, these studies are in a very early stage, but the results from them are very promising and it might not be long until patients with neural diseases or traumas are treated by inhaling their drugs supplemented with xenon. That would overcome many issues with drug delivery to the brain – if a trauma is severe enough, inhaling the drugs might be the only chance to go – in does not require the patient being conscious, or able to swallow and delivering drugs via the airways  is much faster for them to reach the bloodstream and brain, unharmed by powerful digestive acids and enzymes for example.

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Imaging of Xe accessing the brain from a Xe-contrainer (left)

In fundamental science, xenon is used in cell imaging (more precisely using the radiation emission of one of Xe isotopes), in nuclear magnetic resonance experiments due to its flexible electron shell, and in facilities which monitor and detect deviations from the radioactive background to detect leaks, spot nuclear testing experiments or irregular use of nuclear energy.

The latest hype, starring xenon, came out from the University of Basel which was able to finally measure the Van-der-Waals force between individual atoms. This is a non-chemical interaction between atoms, groups of atoms or whole molecules. While its existence was known for more than a century, we were until now unable to measure its strength. The scientist from Basel managed to attach a single Xe atom to the tip of a cryo atomic force microscope.² Then they created nano-cups of copper and in them inserted a single atom of different noble gases. Turns out that for Xe of all noble gases tested, the Vad-der-Waals force they could measure is almost twice as stronger as any theoretical calculation had suggested before, still being the smallest practically measurable force. And as usual, a million of small seemingly insignificant forces can prove incredibly strong – the Van-der-Waals forces being weak, but famously – the “magic” force that allows geckos and some insects and spiders to effortlessly climb, crawl and stick to very very slippery surfaces³.

 

In the end, it proves useful to be inert in normal conditions (for a chemical at least) – when we get tired of big bangs on atomic scale and fireworks on molecular level, it’s time to look up the “quiet guy” and see what knowledge for the micro- and macro-universe he can give us. Go, Xenon!

 

 


  1. The synaptic cavity is the very tiny inter-cellular space between neurons where the communication between these cells happens by the release of a neurotransmitter from one neuron and it’s picked up by the neighboring neuron.
  2. Here you can find out how an atomic force microscope works.
  3. Another innovation based on the abilities of animals to use the Van-der-Waals force

 

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