Nanorods created with firefly enzymes glow orange. The custom, quantum nanorods are created in the laboratory of Mathew Maye, assistant professor of chemistry.

What do fireflies, nanorods, and Christmas
lights have in common? Someday, consumers may be able to purchase multicolor
strings of light that don’t need electricity or batteries to glow. Scientists
at Syracuse University (SU) found a new way to harness the natural light
produced by fireflies (called bioluminescence) using nanoscience. Their
breakthrough produces a system that is 20 to 30 times more efficient than those
produced during previous experiments.

It’s all about the size and structure of
the custom, quantum nanorods, which are produced in the laboratory by Mathew
Maye, assistant professor of chemistry in SU’s College of Arts
and Sciences; and Rebeka Alam, a chemistry PhD candidate. Maye is also a member
of the Syracuse Biomaterials Institute.

“Firefly light is one of nature’s best
examples of bioluminescence,” Maye says. “The light is extremely bright and
efficient. We’ve found a new way to harness biology for non-biological
applications by manipulating the interface between the biological and
non-biological components.”

Their work, “Designing Quantum Rods for
Optimized Energy Transfer with Firefly Luciferase Enzymes,” was published
online in Nano Letters.

Fireflies produce light through a chemical
reaction between luciferin and its counterpart, the enzyme luciferase. In
Maye’s laboratory, the enzyme is attached to the nanorod’s surface; luciferin,
which is added later, serves as the fuel. The energy that is released when the
fuel and the enzyme interact is transferred to the nanorods, causing them to
glow. The process is called Bioluminescence Resonance Energy Transfer (BRET).

“The trick to increasing the efficiency of
the system is to decrease the distance between the enzyme and the surface of
the rod and to optimize the rod’s architecture,” Maye says. “We designed a way
to chemically attach, genetically manipulated luciferase enzymes directly to
the surface of the nanorod.” Maye’s collaborators at Connecticut College
provided the genetically manipulated luciferase enzyme.

The nanorods are composed of an outer shell
of cadmium sulfide and an inner core of cadmium seleneide. Both are
semiconductor metals. Manipulating the size of the core, and the length of the
rod, alters the color of the light that is produced. The colors produced in the
laboratory are not possible for fireflies. Maye’s nanorods glow green, orange,
and red. Fireflies naturally emit a yellowish glow. The efficiency of the
system is measured on a BRET scale. The researchers found their most efficient
rods (BRET scale of 44) occurred for a special rod architecture (called
rod-in-rod) that emitted light in the near-infrared light range. Infrared light
has longer wavelengths than visible light and is invisible to the eye. Infrared
illumination is important for such things as night vision goggles, telescopes,
cameras, and medical imaging.

Maye’s and Alam’s firefly-conjugated
nanorods currently exist only in their chemistry laboratory. Additional
research is ongoing to develop methods of sustaining the chemical reaction—and
energy transfer—for longer periods of time and to scale-up the system. Maye
believes the system holds the most promise for future technologies that that
will convert chemical energy directly to light; however, the idea of glowing
nanorods substituting for LED lights is not the stuff of science fiction.

“The nanorods are made of the same
materials used in computer chips, solar panels, and LED lights,” Maye says. “It’s conceivable that someday firefly-coated nanorods could be inserted into
LED-type lights that you don’t have to plug in.”

Source: Syracuse University