While various devices are being invented/created using nano-materials, Professor Ashok Sahni, an eminent palaeontologist and Professor emeritus of Punjab University, Chandigarh has floated a new concept which is going to take the world of physicists by storm.

Prof. Sahni has studied fossil teeth for more than three decades. Delivering his Presidential Address in the XXI Indian Colloquium on Micropalaeontology and Stratigraphy, hosted by the Birbal Sahni Institute of Palaeobotany (BSIP) at Lucknow on 16th November, 2007, he emphasized the need for an interaction between the nano-scientists and biologists.

He cites the example of rodent teeth, which he says are the hardest material available on the earth, because, a rat can cut through any matter.

‘The enamel of a rodent’s incisor is the hardest material and the animal has a way of keeping it sharp,’ says Professor Sahni. Comparing it with a Khukri he says the rodent teeth has a softer inner layer and a very hard outer layer made of apatite crystals. As the harder material is eroded due to usage, the exposed softer material gets hardened in no time.

From the archaic phyto-planktons to recent dental enamel of different animals, and bones, all are made up of nano scale particles of biomaterials. Scanning electron microscope (SEM) pictures of the enamels of rats and hyenas show different arrangement of ‘prisms’ of apatite crystals according to the function of a particular tooth.

This arrangement has varied through the passage of time, depending upon the type of food or function the tooth had to perform. The latter naturally depends upon the contemporary environment in which the animal lives.
One wonders at nature’s nanotechnology. Apatite has a hardness 5 in the Moh’s scale of hardness. Whereas, fossil rodents are known to have eaten grass that contained silica phytoliths as strengthening skeletal tissue with a hardness 7.

This was possible only because of a particular arrangement of ‘prisms’ in the enamel of the rodents, which gave them the ‘extra hardness’ to cut through the grass.

Similarly teeth performing various functions like slicing, piercing, pounding and shearing had apatite crystals arranged as ‘prisms’ or clusters of various shapes.

Compared to a rodent’s enamel, hyena’s teeth have to perform more of shearing function, thus the ‘prisms’ of apatite crystals are arranged differently.

Considering the antiquity of the nature’s nanotechnology, it is time that the contemporary nano-engineers sit across the table with biologists and paleo-biologists to exchange ideas on the marvels of nature in the field. And develop nano-materials the way the nature has been doing since ages.