GLOBAL CHALLENGES

Implanted 'Microworms' for Better Medical Monitoring

Rebecca Kutzer-Rice | Date: 03-03-11 | Comments

In a novel biomedical monitoring system, tiny tubes implanted into the skin can provide vital information about the body and deliver drugs to specific organs.

For many with chronic illnesses, monitoring critical bodily information�like blood sugar or blood pressure�is a time-consuming, and sometimes painful, daily chore. Diabetics must prick themselves with needles, and people suffering from hypertension must submit to frequent tests. Now, thanks to researchers at the Massachusetts Institute for Technology and Northwestern University, monitoring your health could soon be as simple as glancing down at your arm.

Past research projects have already developed microparticle-based systems for biomedical monitoring. These devices, which consist of hollow, chemical-filled, spherical microscopic particles, can also be used for better drug delivery. But the major drawback of such systems is that they are so small that the body sweeps them away after time. The new tool avoids this problem by implementing a new kind of microparticle.

Researchers developed tube-shaped microparticles, whose narrow width keeps them closely integrated into blood or body tissues. The novel shape also makes it easier for the tubes to sense and respond to chemical changes.

The tiny "microworms" are so small that they are imperceptible to the human body. Despite their size, the tubes are more durable for long-term use than previous implanted systems. (Source: Gleason Lab/MIT)

The length of the tiny "microworms" keeps them anchored in place, so the new system could be used for long-term monitoring. The tool could become an invaluable biomedical monitoring device to measure blood sugar levels in diabetics and sodium levels in people with salt-related conditions, the researchers said.

In developing the system, researchers used a process known as chemical vapor deposition (CVD). In CVD, materials are coated by vaporizing the coating material into a gas and then letting it deposit through condensation. To make the microworms, researchers used CVD to coat an aluminum oxide layer filled with tiny pores. The coating extends down into the pores and then is dissolved away. This leaves a string of hollow tubes where the pores used to be.

Before the coating is dissolved, other materials can be added, such as drugs or material that fluoresces (lights up) in response to specific chemicals. "One can imagine using these kinds of tubes to shrink-wrap just about anything," said Karen Gleason in a statement. Gleason is the Alexander and I. Michael Kasser Professor of Chemical Engineering at MIT.

The microworms can be injected into the skin to form a fluorescing tattoo whose light "is visible to the human eye, and thus can be directly interpreted by the patient without the need for bulky monitors," said Gleason.

The original microworms were successfully used to monitor salt levels in mice, and they could also be used to monitor blood sugar. "Tight control over glucose levels can help individuals stave off the devastating side-effects of diabetes, the No. 1 cause of kidney failure, blindness in adults, nervous system damage, and amputations and also a major risk factor for heart failure, stroke and birth defects," Gleason said.

The microworms are so tiny�just 200 nanometers across, less than one-hundredth the width of a human hair�that they are imperceptible. "The body doesn't even think they're there," Gleason said.

In addition to biomedical monitoring, the CVD-produced tubes could have other applications, such as in the semiconductor industry.

Other researchers on the project included Heather Clark, professor of pharmaceutical science at Northeastern University; MIT postdoctoral researcher Gozde Ozaydin-Ince; and Northeastern doctoral student J. Matthew Dubach. Their findings, published online in January, will soon appear in print in the journal Proceedings of the National Academy of Sciences.