The Future of Medical Materials

28 July 2010 (Last Updated July 28th, 2010 18:30)

Scientists are developing highly innovative uses for both old and new materials in medical devices. Catherine Park investigates.

The Future of Medical Materials

Those of us who are old enough will remember the 1966 film Fantastic Voyage. It involved a submarine being shrunk to microscopic size and injected into the blood stream of a famous scientist along with a miniaturised crew. These were able to remove a blood clot in the physicist's brain and, therefore, save his life.

The plot would have seemed entertaining but completely fanciful for most years that have passed since then. The fact that it has a less outlandish quality now – albeit still far removed from our current experiences in terms of the precise story line – is down to two things: the general speed of advances in medical technology and increasing use of nanotechnology, which involves scaling down devices and their components to molecular levels.

Drivers for such developments have included the desire for reduced risk of infection, enhanced healing properties, more effective implants and better but less intrusive monitoring. All of which has led to a veritable tide of new materials, and old materials used in completely new ways, with leading-edge and cross-over technology making it all possible.

Of course, we are all familiar with the role that the electronic and semiconductor sectors have played in improving patient care, through diagnostic equipment and implants. A big focus has been on establishing which materials do not degrade in the body or carry a risk of having an adverse effect on the recipient.

From stainless steel, the shift has been towards platinum iridium, titanium and the PEEK-Optima polymer, which is used in a variety of engineering applications.

New material frontiers

"Scientists have developed ultra-thin, flexible implants containing metal electrodes that are embedded in silk."

US researchers recently announced the first use of flexible silicon technology for a medical application with the creation of a new type of implantable device for measuring the heart's electrical output. The device, which is made of nanoscale, flexible ribbons of silicon embedded with 288 electrodes, enables electronic circuits to be brought right to the tissue rather than having them located remotely, which, in turn, allows a much higher number of electrodes for sensing or stimulation. And getting that bit closer to science fiction territory, a team of scientists in Barcelona has been experimenting with inserting semiconductors into individual cells, a technique that may bring important benefits for medical monitoring in the future.

Electronics are also now being combined with textiles – namely silk – to help individuals suffering from neurological disorders. Scientists from the University of Pennsylvania, the University of Illinois and Tufts University have developed ultra-thin, flexible implants containing metal electrodes that are embedded in silk. These can hug the brain like shrink wrap, collapse into its grooves and stretch over its rounded surfaces. In people with epilepsy, the implants could be used to detect when a seizure first begins and deliver pulses to shut it down. In people with spinal cord injuries, the technology has promise for reading complex signals in the brain that direct movement, and routing these signals to healthy muscles or prosthetic devices.

Precious stones and metals are also playing an important part in taking healthcare to the next level. Diamonds have often had a role in industrial contexts. Now a Northwestern University study has shown that coupling the contrast agent used in magnetic resonance imaging with a nanodiamond results in dramatically enhanced signal intensity and thus vivid image contrast.

Using nanoparticle technology, antimicrobial silver is being applied to device surfaces, too – a strategy that defends against life-threatening infections by preventing the formation of biofilms on equipment.

Turning the old into new

A number of ancient materials are having something of a makeover in the quest for improved treatments.

"Using nanoparticle technology, antimicrobial silver is being applied to device surfaces."

Wooden prosthetics have been around for thousands of years - the earliest known reference was made around 500BC when Herodotus wrote of a prisoner who escaped from his chains by cutting off his foot, later replacing it with a wooden substitute. However, wood is getting a 21st century twist with the announcement that Italian scientists at the Institute of Science and Technology for Ceramics, Faenza, have been subjecting wood to a variety of processes that turn it into a material more like bone. This development paves the way for prosthetic devices, which get closer to the extraordinary performance of human tissue.

Glass is getting in on the act, too, with the development of a method of bundling thousands of nano-sized glass tubes, each having a conducting carbon core. This technology may make possible artificial neural bundles to interface with prostheses and for use in surgery of the nervous system.

A wealth of materials with origins ranging from ancient history to the space age, along with a cross-disciplinary approach to science, are contributing towards today's advances in medical technology. And that means that today's science fiction could become a reality sooner than you think.