Researchers at Cork Institute of Technology are developing a drug-delivery capsule whose dimensions range from one thousandth of the diameter of a human hair down to the size of a few atoms.
The capsule can be injected into the bloodstream, where it can disintegrate, releasing its drug, or can be targeted at a part of the body.
Dr Liam McDonnell, a senior lecturer in its department of applied physics and instrumentation, is leading research to create the capsule at the micro level - about the size of blood cells - then manufacture it at the nano level.
His team is using photofabrication to create the capsules. The technique converts a liquid to a solid by shining a light at a particular wavelength into the liquid, creating a three-dimensional structure.
The capsules can be any shape, but they must be small enough to pass through the capillaries to avoid clotting. McDonnell says the aim is to create capsules that are one-fifth the size of a red blood cell. Although larger than the proposed capsules, red blood cells are extremely flexible and can squeeze through tiny openings. Once created, the capsule can be filled with a drug; alternatively, it can be solid, with a drug embedded in it. If the drug is for general application, the capsule can dissolve in the bloodstream, releasing the chemicals.
The method of targeting a drug-filled capsule at a part of the body uses natural bonding techniques. The capsule can be coated with an antibody, a protein that primarily defends the body against antigens, which are toxins or other foreign substances that induce an immune response. As an antibody recognises only one type of antigen, this method ensures that the drug is delivered to where it is needed.
Once the capsule reaches its target, there are several ways it can unload its cargo. It can release the drug on a time-release basis - the capsule dissolving two days after it enters the body, for example - or external stimuli, such as ultrasonic waves, can make the capsule disintegrate. McDonnell says the "potential for drug-delivery systems is large" with this type of technology. The researchers are trying to develop the process and manufacturing tools to create the objects at the nano level.
"The principles are clear-cut. We have the material and the processes. The problem is scaling it down to build at this level . . . If we can build on this scale, everything else will unfold. It is a significant challenge."
But drug-delivery is only one potential application for the institute's nano-scale science and technology research programme, which the school of biological sciences is also taking part in. It is examining the manufacture of products on the nano scale, a process to which there are two approaches. The first, known as top-down, is where products are created at a larger scale, then shrunk. In the other, bottom-up, assembly is automatic. For example, humans self-assemble, developing from the bottom up.
The institute is combining the approaches to create what O'Donnell refers to as a hybrid style. Its work has focused on exploiting the strong bonds created between antibodies and antigens to construct objects at the nano scale. One surface is coated with an antibody, while another contains the antigen. They can be directed towards each other, either naturally or with the help of magnetism, and will then lock together.