Tinker Bell, a Disney cartoon figure, is a fairy who flies with magic power from gold dust. Sprinklings of it may add magic to our lives too says the latest reports from Nature, the science magazine.
This news is one that will make the advocates of Siddha medicine wag their finger saying, “I told you so!” There is an ayurvedic medicine called swarnabhaspam which is made of small quantities of gold and there are many other medicines that use the yellow metal in their preparation. The report from scientific research on the metal says, “A nanoparticle of gold, the size of a virus is easy to manipulate to harness the surface property of gold. For example molecules like drugs can be attached to the surface with the help of sulphur atoms which can form covalent bonds with gold. The gold can then carry these medicines to where they are needed in the body. Inert gold is a good delivery vehicle because it does not react with other molecules in the body,” says the report. It is precisely because gold does not react with oxygen that it is good material for ornaments. It never loses shine.
At one level it carries the medicine into the body. At another level, the use of gold becomes even more powerful when the particle becomes smaller in size, about 2/3rds the size of a virus. Says the report, “At this scale gold nanopraticles can be used to exploit a special interaction between light and matter; because gold is a metal some of its electrons are free to move around. If just the right wave length of light is used these electrons can be made to oscillate all at the same frequency. This special property is called surface plasmon resonance. And it could be used to turn gold nanoparticles into very precise cancer killers. Rod shaped nanoparticles have antibodies attached to their surface that allow them to bind only to tumour cells and not to healthy cells. Once enough of them have accumulated in the tumour infra-red light is used to make their electrons oscillate. The energy from these oscillations spreads to the surrounding areas and a sudden temperature increase kills these cancer cells.” This possibility is being actively tested and researched.
The report goes on to tell us that gold nanoparticles of different sizes absorb different wave lengths of light. The particles may differ only marginally in size and even that affects changes the wavelengths of light they are able to absorb. So by gathering together different sizes of nanoparticles of gold it should be possible to make solar cells that absorb different wave lengths of sunlight. Scientists are working on this possibility as one way to enhance the efficacy of solar cells. Do not be surprised then if you can truthfully say that you are sitting in the light of gold!
If the adage small is beautiful holds true for anything, it is for gold. In even smaller particles of gold, not visible to the naked eye, the proportion of surface atoms increases and the electronic and structural properties of gold change and this gets chemists interested for it is only now that gold can react with stuff. Tiny pieces of gold turn out to be good catalysts, for example clusters of ten or so atoms can turn carbon monoxide into carbon dioxide just like platinum does in the catalytic converter in the car. Scientists are looking at such small particles of gold to make greener ways to make industrially important chemicals like hydrogen peroxide. Even when gold is used to make solar cells more powerful, it becomes an environmentally friendly move. But that is not all. Gold can be used to purify water too by breaking down organic contaminants.
While the talk was exciting to listen to it makes one nervous to think, how much gold does our earth still have?
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