One common formula for the construction of nanoshells is to use silica for the core and another sticky compound to adhere gold particles to the outside surface, creating the shell. Nanoshells such as these have been used to kill cancer cells in mice. Once injected into a tumor, infrared radiation is applied and the nanoshells heat up enough to kill the tumor cells.
Early research in this area indicated that only tumors close to the surface of the skin could be treated with nanoshells, because only these could be visualized using the low energy infrared light that made the shells glow. Researchers speculated that the nanoshells accumulated near tumors because of the increased permeability of blood vessels in tumors compared to normal tissue.
In July 2008, Houston-based Nanospectra Biosciences Inc. obtained FDA approval to test this technology in humans with head and neck cancers and in November 2008 the company announced receiving funding from the NCI, to study the safety of the nanoparticles. The pilot-scale study was allowed up to 15 patients. In January 2009 the company announced continued funding of the project based on pre-clinical results, suggesting the technology continues to look promising.