Scientists have successfully developed a chemical process that converts visible light into infrared light, allowing harmless infrared radiation to penetrate living tissues and other materials while avoiding damage caused by high-intensity light.

Scientists at Columbia University, working with researchers at Harvard University, have successfully developed a chemical process that converts visible light into infrared light, allowing harmless radiation to penetrate living tissues and other materials while avoiding damage caused by high-intensity light exposure.

"The results are exciting because we are able to perform a series of complex chemical transformations that typically require the use of noninvasive infrared light sources to generate high energy visible light," said Tomislav Rovis, a professor of chemistry at Columbia University and co-author of the study. "It is conceivable that many potential applications, for example, some of the barriers to application are difficult to control substances. For example, this study has the potential to increase the scope and effectiveness of photodynamic therapy, which has yet to achieve its full potential in treating cancer."

Their method, called triple fusion up-conversion, involves a series of processes that essentially fuse two infrared photons into a single visible light photon. Most technologies capture only visible light, which means the rest of the solar spectrum is wasted. Triple fusion up-conversion captures low-energy infrared light and converts it to visible light, which is then absorbed by solar panels. Visible light is also easily reflected off many surfaces, while infrared light has longer wavelengths and can penetrate dense material.

"With this technology, we are able to adjust infrared light to the required longer wavelength, allowing us to noninvasively move through a variety of obstacles, such as paper, plastic molds, blood and tissue," Campos said. The researchers even pulsed through two strips of bacon wrapped around a flask.

Current photodynamic therapy is limited to the treatment of local or superficial cancers. "This new technique can bring PDT into areas of the body that were previously inaccessible," Rovis said.
"Compared to poisoning the whole body with a drug that causes malignant and healthy cells to die, the process described here can be seen as a non-toxic drug that combines with infrared to selectively target tumor sites and irradiate cancer cells."
The technology could have profound implications. Infrared light therapy can help treat many diseases and conditions, including traumatic brain injury, damaged nerves and spinal cords, hearing loss and cancer.

Other potential applications include remote management of chemical warehouses, solar power generation and data storage, drug development, sensors, food safety methods, molded bone simulation composites, and processing microelectronic components.
The researchers are now testing photon up-conversion technology in other biological systems. "This opens up unprecedented opportunities to change the way light interacts with organisms," Campos said. "In fact, we are currently using up-conversion technology for tissue construction and drug delivery."