From Wikipedia, the free encyclopedia
A nanoshell is composed of a spherical core of a particular compound surrounded by a shell of a few nanometer of thickness. In Europe it is also referred to as "core-shell."
One of the promising applications concerns the biological field. Research is being performed to create nanoshells with high absorptions at biologically useful wavelengths by altering the thickness of the shells. Particularly, the Near Infra Red region, which corresponds with low absorption by tissue, may be useful.
In the literature, special attention is given to gold nanoshell with a a dielectric core (gold sulfide,silicon dioxide,...). Gold is a biocompatible compound, making it a useful material for medical applications.
Nanoshells are currently being investigated as:
- a treatment for cancer similar to chemotherapy but without the toxic side-effects 
- inexpensive, quick analysis of "samples as small as a single molecule" and builds on Raman spectroscopy 
Nanoshells featured in the fictional Alex Rider book Scorpia, where they were filled with cyanide to kill thousands.
See for example: H. S. Zhou, I. Honma, H. Komiyama, J. W. Haus, Phys. Rev. B, 50, 12 052, 1994
Also in the young children book series Alex Rider the gold covered nanoshells wee released into the heart upon request. The gold nanoshells would pass into the heart and disolve and kill if enough poison was administrated.
-  Best nanotechnology discoveries of 2003
-  Nanoshell Sensor Opens Door For New Methods To Examine Single Molecules
-  PBS NOVA Q&A interview with Halas on nanoshells
-  H. S. Zhou, I. Honma, H. Komiyama, J. W. Haus, Phys. Rev. B, 50, 12 052, 1994