The secret behind a 1,600-year-old Roman chalice kept at the British Museum is the way to a supersensitive new nanotechnology that might help diagnose a human disease or pinpoint biohazards at security checkpoints. Is not this cool?
Lycurgus Cup or the glass chalice bears a scene involving King Lycurgus of Thrace. It appears jade green when lit from the front but blood-red when lit from behind. This is a property that puzzled scientists for decades after the museum acquired the cup in the 1950s. In 1990 researchers in England scrutinized broken fragments under a microscope and discovered that the Roman artisans were nanotechnology pioneers. They had impregnated the glass with particles of silver and gold, ground down until they were as small as 50 nanometers in diameter, less than one-thousandth the size of a grain of table salt. The exact mixture of the precious metals denotes that Romans were well aware of their doing. It is “an amazing feat,” says one of the researchers, archaeologist Ian Freestone of University College London. This is a key to the future.
Nanotech in ancient times work like a this-When hit with light, electrons belonging to the metal flecks vibrate in ways that alter the color depending on the observer’s position. Gang Logan Liu is an engineer at the University of Illinois at Urbana-Champaign. He has long focused on using nanotechnology to diagnose disease, and his colleagues realized that this effect offered untapped potential. Liu says “The Romans knew how to make and use nanoparticles for beautiful art. We wanted to see if this could have scientific applications.”When various fluids filled the cup, Liu suspected, they would change how the vibrating electrons in the glass interacted, and thus the color. But this did not happen.
Because the researchers couldn’t put liquid into the precious artifact itself, they instead imprinted billions of tiny wells onto a plastic plate about the size of a postage stamp and sprayed the wells with gold or silver nanoparticles, essentially creating an array with billions of ultra-miniature Lycurgus Cups. When water, oil, sugar solutions, and salt solutions were poured into the wells, they displayed a range of easy-to-distinguish colors. The prototype was 100 times more sensitive to altered levels of salt in solution than current commercial sensors using similar techniques. It may one day make its way into handheld devices for detecting pathogens in samples of saliva or urine, or for thwarting terrorists trying to carry dangerous liquids onto airplanes.
The real Lycurgus Cup, probably taken out only for special occasions, depicts King Lycurgus ensnared in a tangle of grapevines. It may be due to the evil acts committed against the Greek god of wine, Dionysus.