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A Little Medicine

Kris Schnee

The future of medicine is small. There is a whole host of new inventions now being developed for medical purposes which run counter to the vision of medicine as big MRI machines and bigger HMOs. The next wave of medicine, the next area of fast advance and high profits, is the field’s smallest revolution yet.

A University of Michigan team calls its invention “molecular flypaper.” The team has made balls of polymer about the size of a single cell, coated with imitations of the molecular receptors to which influenza viruses bind. The flypaper balls serve as decoys for viruses, which can’t then attack their real targets. This simple, little idea is one of the first weapons to stop viruses before infection instead of after it.

We have new ways of developing drugs now, taking advantage of the “room at the bottom” of the discovery process. Even with today’s computers, and the clunky modeling software currently in use, we can view a molecule in 3D and see exactly how it binds to another. A very old process has been drafted by biotech researchers too, creating drug evolution by unnatural selection. Many slight variations on a promising new drug are tested at once, and the best are kept for another round of variation. The testing arena is often a tiny “biochip,” which will also be used to test a patient for hundreds of kinds of infection at once.

The military is looking at similar micro-arrays to rapidly sniff out bio-warfare agents, and scientists at MIT are using microscopic channels for their next-generation DNA sequencer. Improved time-release pills have already been made using 3D printing machines, simply by dividing a pill into tiny drug-filled chambers which open one at a time.

Scientists at Rutgers University have already developed a way of turning an old drug into a new one: poly-aspirin. They string together as many as a hundred molecules of ordinary aspirin into an elastic polymer chain. It’s a simple idea, but a great one. Aspirin can irritate the stomach because it breaks down there into salicylic acid, and is also thought to cause kidney damage; poly-aspirin breaks down in the intestine instead, where the acid is neutralized, solving at least the first problem with normal aspirin. One little change on the molecular level, from single-molecule to polymer, will make one of the most common drugs safer and more effective.

Today, having a heart attack means taking some aspirin and hoping that help comes quickly. Tomorrow it will probably be poly-aspirin, but after that it may be “respirocytes” instead: injectable devices which travel to the heart and brain and release oxygen in time to save both. Coupled with cloning technology for a limitless supply of spare hearts, and common-sense measures like putting more defibrillators in public places (not to mention diet and exercise!), this research will threaten the heart attack’s rank as one of America’s leading killers.

A toned-down version of respirocytes, passively floating in the bloodstream until activated by internal sensors or a radio signal, makes much more sense as a short-term goal. But farther away, the pieces are already coming together for the real thing, the device which will hopefully be the precursor of the best medicine of all: a nanotech machine which can manipulate individual cells.

Raw materials can be concentrated biologically for nano-scale construction. Swedish scientists reported last year that they had found a strain of bacteria living in silver mines which could concentrate silver, normally toxic to bacteria, into nearly pure crystals. In the lab, they produced triangles and hexagons about 200 nm in size.

Putting pieces of tiny machinery into coherent order is vital to building anything useful at that scale. At the University of Massachusetts, that order is appearing: gold balls just 2 nm across are being made to stick to each other. The gold is coated with a polymer which attaches the spheres, creating networks thousands of times larger than the individual components -- exactly what we need. And at the Ruhr University in Germany, a more elaborate system has been developed, using DNA. At Ruhr, gold balls were coated with single-stranded DNA so that they would attach in precise order to certain other balls, wherever their DNA tags matched. Cylinders, squares, and tetrahedrons have already been built this way.

At Cornell, the third example of a nano-scale motor was invented. The device consists of a rotating protein shaft attached to the energy-storage molecule ATP, and run at 180 to 240 RPM. The next step is to build useful motors, pumps, and other devices out of moving parts like the Cornell motor.

So many of the basic components of the future cellular surgeon already exist that developing it is sure to be a major focus of medical research in the years ahead. But even if efforts in that direction prove unsuccessful, the trend is clear: small medicine is going to be the next big thing.