The photovoltaic effect has been used to convert solar energy to electricity for powering appliances in and around our homes and offices for quite some time. Another application involves converting solar energy to heat using the photothermal effect, and using that energy for surgical purposes, for example in the treatment of blood vessel lesions and laser treatments.
Photothermal therapy for cancer is still in experimental stages and limited to mice. The process involves using infra red light to excite a photosensitizer. This could be any material which absorbs light and then releases energy. The heat energy released is focused on malignant cancer cells to destroy them.
Nanotechnology is the science of manipulating matter at an atomic level, of sizes below 100 nanometers. There are 1,000,000 nanometers in 1mm, so you can imagine how tin these particles would be. Photothermal therapy requires that a nanoparticle (which will release heat, and kill the surrounding cells, when exposed to infra red light), be embedded in the tumor. A major advancement has been in the development and use of gold nano-rods, instead of spherical nanoparticles, for photothermal therapy. This is because spherical gold nanoparticles have limited absorption compared to gold nano-rods, which can absorb up to 80% of incident energy, and are able to effectively generate a large amount of heat from the absorbed light, to kill the surrounding tumor cells.
A similar method of treatment, known as photodynamic therapy, requires the combination of tissue oxygen with the heat released by a photosensitizer, when exposed to light. Since photothermal therapy does not require tissue oxygen, and therefore allows the use of a longer wavelength of light, there is a lesser chance of harm to the surrounding healthy cells and tissues.
With more than 100 types of cancers affecting people all over the world, new treatments for this disease are frequently developed, researched and tested. Photothermal therapy for cancer, with the use of nanoparticles, is one such possible cure. Although all potential applications, side effects and complications are still unknown, Photothermal therapy allows for the targeted treatment of cancer cells, without damaging the surrounding healthy tissues, which are sometimes unavoidably damaged using current treatments like radiation and surgery.
