Richard Feynman is rapidly becoming the Oscar Wilde of Science, in that he is the name one should give in a pub quiz when unsure who to attribute something to. One thing we perhaps shouldn’t credit him with is the birth of nanotechnology. It’s a well known story: Dec 29 1959, Caltech. Feynman gives a talk, entitled Plenty of Room at the Bottom, in which he predicts that we will one day put whole libraries on the head of a pin. One thing leads to another until, in 1989, the word “IBM” is spelled using 35 xenon atoms.
For Sai Maddala, a PhD student at Queen Mary, the story begins some 4.5k years earlier with the manufacture of the pigment Egyptian Blue. A distinctive and popular dye, Egyptian Blue has been found as far afield as Pompeii. One of the reasons for its success has been its durability (not its “beautiful plumage” as one might have guessed). The Egyptians knew that, when it is exposed to the elements, pigment rapidly fades. Not so the Egyptian Blue: by a process of heating copper lime & sand in a furnace Egyptian Blue cools to form sheets 0.87 nanometres (nm) thick, which are extremely resistant to everything except boiling water. Since the definition of a nanomaterial is that one of its dimensions must be under 100 nm (4000 x thinner than your fingernail), this pigment is a good contender for the earliest use of nanomaterials.
Next we move on to a Graeco-Roman method for dying hair black: the technique uses lead oxide, slaked lime, and water to bind 5 nm thick lead particles around keratin proteins in the hair. Despite the worrying mention of lead in cosmetic treatments the technique did not appear to have any ill side effects.
In the 4th Century ad, glassblowers started producing cups that shine one colour when the light comes from one direction and a totally different colour when the light direction changes. Nature has been doing this for millions of years of course (the structural colouration in hummingbirds for example) and is achieved by microstructures in the surface of the material. The Lycurgus Cup at the British Museum is an exquisite example of this. The effect in this particular case is created by gold and silver particles, 70 nm in size, at a ratio of 3 gold to every 7 silver. It is suggested that the process was discovered by accident when glass blowers threw coins into the furnace for luck. Later glass manufacturers would take this a step further by using gold particle research generated by alchemists and apply it to glass pigmentation. They found that, by varying the size and shapes of gold and silver nanoparticles, they could make an array of vivid colours of glass. An example of this later method can be seen in the large round window at Notre Dame, Paris.
When our ancestors gleefully trotted off to “liberate the holy land” they encountered some remarkable technology: Damascus swords with a rather distinctive ripple pattern on their steel blades. These swords were allegedly so sharp you could cleave a piece of silk fabric dropped onto their upturned blades. They also boast being able to cut rocks without blunting. If you’ve ever tried to cut a slice of bread with a steel fish knife you’ll know what an extraordinary claim this is. Recent analysis of these Damascus Swords reveal the presence of carbon nanotubes surrounded by a 50 nm layer of cementite. By treating the finished blade with a powerful acid (hence the wave patterns on the surface) the carbon nanotubes are drawn up to the surface, providing the legendary qualities described. Wootz steel manufactured this way has its origins in India at least as far back as 300 bc, though some argue it’s even older. Could this be the earliest non-aesthetic application of nanotechnology?
I am not doing justice to Sai’s talk: he mentioned much more than this including the 7th Century process of trapping pigment in clay at the Yuccatan peninsula, as well as a run-down of the key figures, discoveries and inventions which contributed to our modern understanding of nanotechnology, such as: Faraday’s experiments in the 20’s with gold nanoparticles; Richard Zsigmondy and the ultramicroscope; Jean-Baptiste Perrin and Avogadro’s Constant; Sir Humphry Davy; Döbereiner’s lamp & lighter; platinum sponge; Paul Sabatier and the hydrogenised nickel catalyst; G. Binning & H. Rohrer’s scanning tunneling microscope… I know I’m missing a few. Keep an eye out for this guy: the subject of his PhD has some amazing nanotechnological applications for modern medicine.
Join us on the 9th September when PubSci will be turning its attention to Syphilis in Southwark.