problems, new approaches for early detection and treatment of diseases will be required. Nanomedicine utilizing light-guided and light-activated therapy, with the ability to monitor real-time drug action, will lead to new approaches for more effective and personalized molecular-based therapy.
Nanospheres also have especially sensitive light-scattering properties that make them ideal for use in chemical sensors. The chemical properties of a tiny object like a biomolecule or a nanosphere can be revealed through Raman scattering of light. Owing to the minute amounts of energy left behind in the molecule, the Raman effect causes a tiny reduction in the frequency of light scattered by a chemical. These Raman frequency shifts are optical fingerprints of the chemical species. Nanospheres can be designed so that chemicals embedded in them or attached to their surface exhibit enhanced Raman scattering by a factor of up to a million. This capability creates the opportunity for many new, all-optical remote-sensing applications sensitive to just a few molecules of a drug molecule, disease protein, or other chemical agent.
The optical properties of nanostructures are also expected to have a significant impact on future energy needs—for example, energy consumption for lighting could be reduced by replacing current technologies (incandescent and fluorescent lighting) with solid-state lighting or OLEDs. The size dependence of optical properties at the nanoscale can also be exploited. For example, while bulk silicon has poor optical properties for optoelectronic devices such as solar cells or lasers, at small dimensions the band gap in silicon can be blue-shifted from the infrared to the visible spectrum; as a result, porous silicon exhibits remarkable room-temperature luminescence. Nanotechnology also has considerable potential to reduce the cost of photovoltaic cells, and recent work has demonstrated that thin-film cells based on nanoparticulate materials can be fabricated with reasonable efficiencies and stabilities.
In the next 10 years, exploration of the nanoworld will likely bring a veritable explosion of new science and technology. AMO physics will play an essential role in this exploration and will also reap the benefits of the developments that come from it.