ABSTRACT
There has been a tremendous focus of research effort on nanotechnology in general and nanoparticles specifi cally in the past twenty years. Part of the reason for these efforts is that materials confi ned to nano-sizes (in the range of 1-100 nm in one or more dimensions) can exhibit unusual properties, be it optical, electronic, magnetic, fl uorescent or catalytic. A pertinent example of this is quantum dots, semiconductor-based colloids that, when in the size range 1-10 nm, possess extraordinary fl uorescent properties. Nanoparticles can be formed from a wide variety of materials, including inorganic materials such as gold, silver, platinum, iron oxide, bismuth and cadmium selenide. Such inorganic materials invariably possess some kind of organic coating, but nanoparticles can also be entirely composed of organic materials such as polymers, amphiphiles, sugars or proteins. Some of these coatings, such as polyethylene glycol, have been found to make nanoparticles highly biocompatible and non-toxic both in vitro and in vivo. Nanoparticles are now being explored in the biomedical fi eld for drug delivery, gene therapy and medical imaging, among other applications.
