No Small Feat – student presents at Wychwood Nanochemistry Conference
Greene’s Student, Will, took part in the annual Wychwood School Chemistry Conference, themed on Nanochemistry.
What is Nano?
Nanomaterials are between 1 and 100 nm in at least one, usually two or three dimensions. As such, their surface area to volume ratio is high and, unlike bulk materials, the chemical properties come from the surface atoms. Are these very different from inside atoms? Well, yes. You may remember that diamond, for example, is made up of carbon atoms joined to four other carbon atoms, going on, infinitely… Or that in sodium chloride, every chloride ion is surrounded by six sodium ions, above, below, right, left, before and behind, infinitely. But come to the surface, and now there is a carbon with just two or three bonds, or a chloride ion with no sodium ions on one side. Bonding is incomplete. Bonds may form to other atoms like oxygen in the air.
Strukturen av diamant. Alle kulene er karbonatom.
Modell diamant
Av Petter Gramnæs Tjernshaugen/Store norske leksikon.
Lisens: CC BY SA 4.0
Modell av strukturen i natriumklorid.
Struktur natriumklorid
Av Petter Gramnæs Tjernshaugen.
Lisens: CC BY SA 4.0
https://snl.no/ionebinding
Same stuff, new behaviours
So now you know – the cool thing about nanomaterials is that the same chemicals we already know can exhibit new chemical behaviours. There is gold, and there is nanogold. We have opened up a whole new world of materials. So, what can they do for us?
Nanomaterials are small and can get into places that other things can’t, like sunscreens and cosmetics that sink into our skin, or nanodrugs that cross the blood-brain barrier. They may even be used to navigate DNA/RNA transcription. Did you know our skin absorbs nanodiamonds better than skincare products?
Nanomaterials can act as sensors: they may respond to chemicals or magnetic fields, moving to or away from the stimulus. This way, the movement of nanomaterials can act as a CO2 sensor, or heart rate monitor in sports clothing, nanogels can shrink or swell to ab- or desorb selectively, and nanobots move to cholesterol blocking arteries – where they grind it up.
Or anti-sensors, with unique thermal and optical properties that allow them to deflect radar waves or transform them into undetectable thermal energy. They can heat shield descending rockets passing through places hotter than the surface of the sun, and transform the frequencies of UV rays to be “hyper harmonised” with biostructures. Localised heating can also be used in photothermal cancer treatment, and they may be used for imaging – or art one fifty thousandeth the width of a human hair.
Picture: Wikipedia Commons, William Thielicke Published under the “GNU Free Documentation License” and the “Creative Commons Attribution ShareAlike license”. Citations from the license agreement: https://en.wikipedia.org/wiki/File:Lotus3.jpg
Nanomaterials can deliver other materials. You can fix things to their surfaces, or encapsulate them in nano cages. Only small amounts, but that can be a good thing. Nano cages can deliver drugs to the target site only, increasing efficiency and cutting costs. Lower doses, e.g. in chemotherapy, can also reduce side effects. Zinc or copper nanoparticles can deliver fertiliser to plants, silver sulfide nano portions of insulin – reducing spikes – and encapsulation of vaccines may be used for both delivery and to convey thermal stability – possibly removing the need to refrigerate (by far the limiting factor in vaccination).
Surface science also takes place on materials, providing sites for catalysis, such as photocatalytic degradation of oil spills using Zn/Ti oxides, toxins from soil or water, or of harmful nitrous oxides in air.
In addition to the students, we also heard keynote talks from Professor Dame Carol Robinson, Kavi Institute for Nanotechnology, Dr Mootaz Salman, Kavi Institute for Nanotechnology, Professor Iakovos Tzanakis, Oxford Brookes, and Professor Sonia Contera, Oxford Physics. The all-star crew measured shock waves from bubbles, stuck geckos to walls with setae, moved atoms on the surface of materials, and bridged between quantum mechanics and general relativity.
Will’s talk focussed on nanomaterials in food preservation. Nanosensors in packaging can detect the small, volatile, and unstable compounds formed when food goes bad, and warn us about it. Nanoparticles can hold emulsions together, or act as preservative coatings. And yes, that means if you’ve just had lunch, you’ve just eaten nanoparticles. Are they safe? Regulation in food (and cosmetics) is tricky when the only difference between nanomaterials and other materials already approved for use in food is size – but this can change their behaviour and penetration in ways we’re still learning about.
So what is the future? As Will said, the most strenuous R&D process ever has already taken place – evolution – and the ideas are out there: from setae on the gecko’s feet to the self-cleaning nanosurface of the lotus leaf. It’s time to plagiarise nature!
