Hold the 4th century Lycurgus cup up to the light and watch as it mysteriously morphs from green to red. This mystical colour transition is not magic though, it’s nanoscience: tiny colloidal particles of gold and silver cause the glass to flit between red and green depending on the direction of the light source. Humans have inadvertently capitalised on the properties of tiny, nanoscale properties like this for centuries, from manufacturing stained glass windows to forging Damascus sabre blades.
The potential of harnessing this sub-molecular domain was first presented to the world by effervescent physicist Richard Feynman in his famous 1959 address There’s Plenty of Room at the Bottom. However, it wasn’t until the invention of the scanning tunnelling microscope in 1981 that scientists were first able to ‘see’ materials on such a minute scale. And in visualising this microscopic world, a window was opened to a whole new realm of material science.
So just how small are nanostructures? A nanometer is one billionth of a metre, which is about a hundred thousandth of the diameter of the average human hair. Nanotechnology encompasses the study and application of matter with dimensions between 1 and 100 nanometers. This means that scientists are not manipulating the molecules in a material, but the arrangement of the atoms themselves.
In 1991, a team of Japanese scientists constructed a new formation of carbon atoms – the carbon nanotube. It consisted of a single layer of carbon, just 1-atom thick, rolled into a cylinder. Carbon nanotubes can be hundreds of times stronger than steel, yet they are six times lighter. Alternatively, they can be arranged into highly efficient semi-conductors that outperform copper at carrying electrical current.
The nanotube is just one example, but a plethora of possibilities arise from fiddling around with atomic arrangement. Many of the early applications already quietly influence our lives: the scratch-resistant coating on spectacles is derived from engineered aluminium silicate nanoparticles; almost all high-powered electronic devices rely on the superior transistor structures built from nanomaterials; even dentistry is benefiting from nanoceramic implants that have been ‘tuned’ to attract bone cells from surrounding tissue.
The field of nanotechnology research is booming. This year, the journal Nature Nanotechnology published research demonstrating new luminescent nanocrystals that can penetrate deep into biological tissue, revolutionising bio-imaging. In the same month, scientists built gold nanoshells that can encapsulate chemotherapeutic drugs, and target them specifically at cancer cells whilst leaving healthy cells unharmed. Ongoing nano-work points towards the development of energy efficient fuel cells, food packaging with improved shelf life, bacteria resistant textiles, and super-strong and super-light construction materials that could revolutionise transport infrastructures.
As with most growing fields in science, the results of nanoresearch are likely to quietly trickle into our lives. Rest assured though, these tiny structures hold a transformative power far greater than their diminutive size suggests and that will undoubtedly influence scientific development on a grand scale.
Top image: Ice nanotube inside a carbon nanotube (featured image manipulated) (Flickr/Masakazu Matsumoto); Lower image: Silver nanocrystals seen by a scanning electron microscope (Flickr/Argonne National Laboratory)