Researchers at the University of Connecticut have made a new material that emits bright white light by adding fluorescent dyes to DNA and then spinning the DNA strands into nanofibers, according to a paper published online in the journal Angewandte Chemie. The researchers create white-light-emitting devices by coating ultraviolet (UV) light-emitting diodes (LEDs) with the material. They are even able to fine-tune the white color tone to make it warm or cold.

DNA light: Coating an ultraviolet LED with DNA nanofibers containing dyes creates a bulb that emits bright white light.
Credit: Angewandte Chemie 

The material absorbs energy from ultraviolet light and gives off different colors of light depending on the proportions of dye it contains. It could be used to make a novel type of organic light bulb. The light emitters should also be longer-lasting because DNA is a very strong polymer, the research team leader, chemistry professor Gregory Sotzing says. "It's well beyond other polymers [in strength]".

The material relies on an energy-transfer mechanism between two different fluorescent dyes. The key is to keep the dye molecules separated at a distance of 2 to 10 nanometers from each other. When UV light is shined on the material, one dye absorbs the energy and produces blue light. If the other dye molecule is at the right distance, it will absorb part of that blue-light energy and emit orange light.

The combined color of light that the material gives off can be altered by changing the ratio of the two dyes. Varying the amount of dye also lets them make finer tweaks. For example, by increasing the proportion of dye in the DNA from 1.33 percent to 10 percent, they can change the white light from cool to warm. "As you go across the white spectrum, if you want a soft yellow-type light or blue-type light, you can get these very easily with the DNA system," Sotzing says.

"The advantage in the present system seems to be that the DNA fibers orient the dyes in an optimum way for efficient [fluorescence energy transfer] to occur." David Walt said. Furthermore, when larger amounts of dye are used in the other materials, they start to aggregate. This has two effects: it decreases energy transfer between them, dimming the light output, and it also prevents precise color tuning.