Page 22 - Science at the nanoscale

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June 9, 2009
Introduction and Historical Perspective
12
A more promising application of bionanotechnology that has
attracted much interest from researchers and industries is the
In our modern
development of nano-drug delivery systems.
busy lifestyle, administration of drugs has progressed from the
Nanotechno-
teaspoon to time-release capsules or implants.
logy promises delivery mechanisms that can administer drugs at
desired rates and at the exact location in the body. This requires
the fabrication of precise nanostructures for drug-eluting coatings,
membranes, or even implants, For example, researchers at the
University of California, San Francisco have demonstrated how
they can use nanotubes made from biocompatible metal oxides
to hold therapeutic drugs and deliver these agents in a highly-
7
On the other hand the dendrimer, a highly
controlled manner.
branched polymer, has also been investigated by many as a nat-
ural form of nanoparticle carrying myriad sites for drug loading.
All these developments not only translate to time-saving and bet-
ter treatments, they also help avoid side effects caused by large
doses taken orally or by injection. There are also the potential
benefits of extension of the bioavailability and economic life-
span of proprietary drugs. According to the industry consulting
firm NanoMarkets, nanotechnology-enabled drug delivery sys-
tems are expected to generate over US$1.7 billion in 2009 and over
8
$4.8 billion in 2012.
Another development in nanoscience that has excited many
biomedical researchers is the use of quantum dots (abbreviated
QDs, see Section 6.1) in bio-imaging. These are tiny crystals that
give strong fluorescence signals and, when injected into cells,
allow unprecedented details inside the cells to be imaged. A nice
3D imaging example was demonstrated by Cornell researchers
(Fig. 1.6) whereby tiny blood vessels beneath a mouse’s skin were ch01
viewed with CdSe/ZnS QDs circulating through the bloodstream.
The images appear so bright and vivid in high-resolution that
researchers can see the vessel walls ripple at 640 times per minute.
(b) Spintronics For many years, scientists and engineers have
created a host of electrical devices that rely on electrons in the
materials. Such devices include the ubiquitous transistor and the
7 C. C. Lee, E. R. Gillies, M. E. Fox, S. J. Guillaudeu, J. M. Fr´echet, E. E. Dy and
F. C. Szoka, Proc. Natl. Acad. Sci., USA, 103, 16649–54 (2006).
8 The NanoMarkets report 2005/03 on Nano Drug Delivery: http://www.the-
infoshop.com/study/nan24488 nano drug delivery.html