Billions of Molecular Lamps Driven by Invisible Infrared Photons Produce Visible Light
Scientists at Columbia University, in collaboration with researchers from Harvard, have succeeded in developing a chemical process for converting visible light into infrared energy harmless radiation can invade living tissue and other materials without suffering the damage of high-intensity light.
"The results are exciting because we were able to perform a series of complex chemical transformations, usually high-energy, visible light with a non-invasive infrared light source, "said Tomislav Rovis, chemistry professor at Columbia and co-author of the study. "There are many possible applications in which barriers to the control of matter can be imagined, for example, research promises to increase the reach and effectiveness of photodynamic therapy, whose potential to treat cancer has not been fully exploited."  The team, which includes Luis M. Campos, associate professor of chemistry at Columbia, and Daniel M. Congreve of the Rowland Institute at Harvard, conducted a series of experiments with small amounts of a novel compound that, when passed through light stimulated, which can mediate the transfer of electrons between molecules that would otherwise slow or fail to react.
Their approach, the so-called triplet fusion upconversion, involves a chain of processes that transform essentially two infrared photons into a single one Photon merge with visible light. Most technologies capture only visible light, i. the rest of the solar spectrum is lost. The upconversion of the triplet fusion can acquire low energy infrared light and convert it to light, which is then absorbed by the solar modules. Visible light is also easily reflected by many surfaces, while infrared light has longer wavelengths that can penetrate dense materials.
"With this technology, we were able to tune the infrared light to the necessary, longer wavelengths that allowed us a wide variety of wavelengths Barriers such as paper, plastic molds, blood and tissue happen non-invasively, "said Campos. The researchers even pulsed light through two strips of bacon wrapped around a bottle.
Scientists have long attempted to solve the problem of how to allow visible light to penetrate the skin and blood, without damaging internal organs or healthy tissue , Photodynamic therapy (PDT), which is used to treat some cancers, uses a special drug, the so-called photosensitizer, which is triggered by light to produce a highly reactive form of oxygen that is capable of supporting the growth of cancer cells to kill or inhibit.
Current photodynamic therapy is limited to the treatment of localized or superficial cancers. "This new technology could bring PDT into areas of the body that were previously inaccessible," Rovis said.
"Instead of poisoning the entire body with a drug that causes the death of malignant cells and healthy cells, could be a non-toxic drug in combination with infrared light, selectively attack the tumor site and irradiate cancer cells. "
The technology could have far-reaching effects. Infrared light therapy can play an important role in the treatment of a variety of diseases and conditions, including traumatic brain injury, damaged nerves and spinal cord, hearing loss, and cancer.
Other potential applications include remote management of solar energy production and storage of drug storage, drug development, Sensors, food safety methods, malleable bone-like composites and processing of microelectronic components.
Researchers are currently testing photon-up conversion technologies in other biological systems. "This opens up unprecedented opportunities to change the way light interacts with living organisms," Campos said. "In fact, we are currently using upconversion techniques for tissue engineering and drug delivery."