The nano science of kajal

Nano derives from the Greek nanos, or a dwarf. In actual measurement, a nanometre is a billionth of a metre, nanotechnology, therefore, dealing with particles smaller than in microtechnology. Nanotech, in its basic sense, is using molecular building blocks in an array of applications, from medicine and manufacturing to biotech and optics.

Unique among elements, carbon can bond to form sheets that can be rolled into tubular fibres, known to be among the strongest fibres known, 10 to 100 times stronger than steel by weight.

Sabyasachi Sarkar, a chemistry professor at IIT-K, was working on the production of fullerenes, another ball-shaped, sub-micro structure, in 1992, when he detected that waste insoluble carbon soot seemed to have a substantial amount of CNT. Based on this finding, Sarkar tried to produce CNT from the traditional oil-burning lamp in which pure carbon, or kajal, is produced.

After his initial studies on generation of CNT, Sarkar was awarded a Rs 32 lakh project by the Indian government’s Department of Science and Technology (DST) in September 1994. He said his focus, as of scientists elsewhere, was on developing a cost-effective method to generate CNT and finding a way to make CNT water soluble for medical use.

He chuckles about how blind we have been over the years. Even the Ramayana and Mahabharata mentioned the kajal. ‘‘Traditionally, the grandmother applies fresh kajal to the six-day-old baby to prevent eye ailments,’’ he added. No one knew this pure carbon could be a source of much-needed carbon nano tubes. As for the other eyeliner, the surma, Sarkar says it is not pure carbon like kajal but emanates from lead sulphide and is of Arabic origin.

Sarkar was able to extract up to 40 per cent of the kajal as CNT. More important, Sarkar not only produced cheap CNT through a traditional method but also managed to make it water-soluble. He did this by treating CNT with nitric acid, which incorporated some hydrophilic groups and thus made it soluble.

CNT has multifarious uses. ‘‘The dry-state uses include manufacturing of picture tube for display devices, which would be much cheaper and less power-consuming,’’ says Sarkar. He also envisages CNT replacing optic fibres used in telecommunication since it minimises distortion of sound and disturbance in the line. Other uses of CNT are in manufacturing of reusable packaging material and in electronics.

Wet-use CNT can be applied in drug delivery. Sarkar said, for instance, that if drug for cancer in a specific body part was to be delivered without affecting the other parts, the magnetic property of CNT was extremely helpful.

‘‘The drug is placed in a CNT and injected into the blood. It is then dragged to the affected part with magnetic material and then blasted using electro-magnetic radiation,’’ he explained. Despite the obvious fallout of his discovery, Sarkar has not patented the process.

‘‘I do science, not business,’’ he said. He suggests the production of kajal should be promoted as a cottage industry that would generate employment for thousands of educated, unemployed people.