Tuesday, March 15, 2005

Current applications of nanomedicine

This article in the Washington Post gives some good examples of current research uses of nanotechnology. Nanotechnology doesn't necessarily mean nano-machines (as in my story earlier) but simply refers to the use of very small technology. The difference between what is considered nanotechnology and technology involving other very small things (such as microprocessors) is more than a matter of scale, however. Nanotechnology is used to describe the situation that exists when the very small size imparts unique properties on the particles.

Such as with qdots. As the size of the qdot changes, the color changes, even if the material is the same. We are used to the color remaining the same between a 1 inch dot of paint and a 1 yard dot of paint. By utilizing the change in color that is associated with the change in size, these very small qdots can be put to medical use:
Scientists are already using quantum dots as research tools to help them understand how proteins, DNA and other biological molecules catch rides on the various transportation systems inside cells. First they coat some qdots with a material that makes the dots attach specifically to the molecule they want to track, then they inject those coated dots into cells growing in laboratory dishes. Once the dots grab their targets, researchers simply watch the trails of colored light to see where they go.
We are all familiar with the imaging techniques that utilize immunologic properties to attach a radio-tracer to the desired target. For example, tagged red cell bleeding studies, or even the now everyday use of radio-immune assays for various diagnostic tests.

This is a very similar process. However, instead of attaching a radio-tracer, you attach a qdot. These qdots simply diffuse throughout the sample into which they are placed and attach according to the qualities of the proteins or other substance being investigated.
There are scores of proteins and other substances in the body that are early indicators of disease but which are difficult to detect with current technologies. While qdots and other nano-materials have not been proved safe for use in the body, they are clearly capable of spotting diseases in blood or tissue specimens. Qdots that bind to proteins unique to cancer cells, for example, can literally bring tumors to light.
Another example in this article is the use of tiny carbon nanotubes. When charged with electrons and exposed to infrared light, these nanotubes glow, a property unique to the physics at this nano-scale. The more the charge, the more the glow. So, with a spectrometer, you can measure the intensity of the glow and calculate the intensity of the charge. When the electrons are created by the presence of glucose, as in this example, these properties can be used to measure glucose concentrations, as in diabetics.

Read the whole thing for very practical applications of todays nano-technology.


This article describes the area inhabited by nanoparticles, between molecules and atoms described by quantum physics and larger particles described by Newtonian physics:
A nanoparticle, an object with a width between a few nanometres and a few hundred, contains tens to thousands of atoms and exists in a realm that straddles the quantum and the Newtonian.

At those sizes "everything, regardless of what it is, has new properties," says Dr Chad A Mirkin, a director of Northwestern University’s Institute for Nanotechnology in Illinois. That, he adds, is "where a lot of the scientific interest is".

This in-between realm gives rise to an unusual physics where the properties of a material change depending on its size.

At the quantum level, one gold atom acts like any other gold atom, and a nugget of gold large enough to see or hold has the same chemical and electrical properties as any other nugget. But two nanoparticles, both made of pure gold, can exhibit markedly different behaviour - different melting temperature, different electrical conductivity, different colour - if one is larger than the other.