which are controlled by their size, geometry, and their surface plasmons. Gold nanoparticles (such as AuNPs) have the benefit of being biocompatible and the flexibility to have multiple different molecules, and fundamental materials, attached to their shell (almost anything that can normally be attached to gold can be attached to the gold nano-shell, which can be used in helping identifying and treating cancer). The treatment of cancer is possible only because of the scattering and absorption that occurs for plasmonics. Under scattering, the gold-plated nano-particles become visible to imaging processes that are tuned to the correct wavelength which is dependent upon the size and geometry of the particles. Under absorption, photothermal ablation occurs, which heats the nanoparticles and their immediate surroundings to temperatures capable of killing the cancer cells. This is accomplished with minimal damage to cells in the body due to the utilization of the "water window" (the spectral range between 800 and 1300 nm). As the human body is mostly water, this optimizes the light used versus the effects rendered. These gold nanoshells are shuttled into tumors by the use of phagocytosis, where phagocytes engulf the nanoshells through the cell membrane to form an internal phagosome, or macrophage. After this it is shuttled into a cell and enzymes are usually used to metabolize it and shuttle it back out of the cell. These nanoshells are not metabolized so for them to be effective they just need to be within the tumor cells and photo-induced cell death (as described above) is used to terminate the tumor cells. This scheme is shown in Figure 2. Nanoparticle-based therapeutics have been successfully delivered into tumors by exploiting the enhanced permeability and retention effect, a property that permits nanoscale structures to be taken up passively into tumors without the assistance of antibodies.[4] Delivery of nanoshells into the important regions of tumors can be very difficult. This is where most nanoshells try to exploit the tumor's natural recruitment of monocytes for delivery as seen in the above figure. This delivery system is called a "Trojan Horse". This process works so well since tumors are about ¾ macrophages and once monocytes are brought into the tumor, it differentiates into macrophages which would also be need to maintain the cargo nanoparticles. Once the nanoshells are at the necrotic center, near-infrared illumination is used to destroy the tumor associated macrophages. Additionally, these nanoparticles can be made to