A New Drug Courier

THE air is thick with despair and disrepair, almost masking the chemical odours in the lab of Delhi University's department of chemistry. Professor A.N. Maitra is anguished at the sorry state of academics. "Nobody's serious about teaching or research here. Politics and corruption reign," he agonises. But he himself has remained immune to the general rot around him. That sincerity and perseverance now seem to have paid off.

Maitra and his colleagues have created the smallest polymer capsules called nano-particles, spheres which have a diameter of less than one-millionth of a millimetre. "We've taken the lead in the world with nanoparticles less than 100 nanometres in diameter," exults Maitra. A feat that has recently been accepted for a US patent.

Maitra's work is at the cutting-edge of a fast-evolving discipline called nanotechnology whereby submicroscopic particles could revolutionise areas as diverse as computers, neurology, drug delivery, cosmetics and anti-pollution technologies. Above all, Maitra's nanoparticles hold great promise as drug-couriers—they can ferry drugs to specific sites in the body. The Lilliputian chaperones may even be used to escort oral vaccines.

For any nanoparticle to be an efficient drug courier it must be able to do three things. First, be small enough to glide unimpeded through the arteries and reach any part of the human body; two, escort the drug to its destination without leakage or abduction by other organs on the way; three, be biodegradable so as not to poison the system.

The problem with existing nanoparticles is that they aren't small enough to reach all parts of the body. Besides, they are hydrophobic (repel water); which makes them susceptible to bodyguards called the Kupffer cells residing in the liver. These have a special affinity for hydrophobic substances and which abduct any such foreign particle that comes their way. Once released into the bloodstream, the nanosphere is ripped open by these cells, the drug inside them released to be absorbed by these affected liver cells. As a consequence, the role of hydrophobic nanoparticles is limited to the treatment of liver diseases.

Maitra's Lilliputs do not suffer this handicap. They love water and hence escape the clutches of 'bilious' monsters. Says Maitra: "When we tried them on mice, we found to our utter surprise that only 1 to 8 per cent were captured in the liver while more than 50 per cent kept wandering for about four hours before finding a resting place. Significantly, about 6 to 10 per cent could still be observed loitering in the blood even after 24 hours." This, explains Maitra, is wonderful, for the longer the nanoparticle stays in the bloodstream the greater the probability of its hitting the desired target. And the more of them reach the target the better.

 Maitra's polymer dwarfs could also carry oral vaccines. The group has prepared 60-nanome-tre particles that have all the necessary attributes to ferry vaccines orally via the stomach to the blood. They are tiny enough to pass through the walls of the stomach and join the bloodstream; they are protean enough to change their acidity so as to escape the stomach's acidic fire and brimstone; and finally sticky enough to hang on to the slippery stomach walls. "We're currently trying out this method for tetanus and hepatitis B vaccines," says Maitra.

Good work, but when will the cash registers start ringing? At least two companies have already approached Maitra. Alcon Laboratories from the US and the very desi Dabur. "Dabur has given me Rs 60,000 worth of taxol, an anti-cancer drug, to try out with my nanoparticles. After the patent is published in the gazette, I expect to get many more calls," says Maitra.

Interestingly, the patent has been filed in the name of the department of biotechnology (DBT) and Delhi University. Maitra and his colleagues couldn't muster enough money—about Rs 13 lakh—to apply for a world patent, which is what the DBT has spent. "Unfortunately, Delhi University has no policy on patents and therefore I don't expect anything out of it. Any profits from the patent's commercial exploitation will be divided equally between the University and the DBT. It is then up to the university whether they want to share the proceeds with me and my colleagues or not," sighs Maitra. If they don't, it would indeed be a pity.