For industry, the potential energy savings alone may make the Rice process worth investigating. "Here we're using 'free' energy," Wong said. "Instead of needing a big boiler to produce steam, you turn on an energy-efficient light bulb, like an LED. Or open a window."
The particle at the center of the process is a gold nanorod about 10 nanometers wide and 30 long that heats up when hit with near-infrared light from a laser. The rods are just the right size and shape to react to light at around 800 nanometers. The light excites surface plasmons that ripple like water in a pool, in this case emitting energy as heat.
Halas' Rice lab is famous for pioneering the use of gold nanoshells (a related material) to treat cancer by targeting tumors with particles that are bulk heated to kill tumors from the inside. The therapy is now in human trials.
The new research takes a somewhat different tack by heating nanoparticles draped with a model thermophilic enzyme, glucokinase, from Aeropyrum pernix. A. pernix is a microbe discovered in 1996 thriving near hot underwater vents off the coast of Japan. At around 176 degrees Fahrenheit, A. pernix degrades glucose, a process necessary to nearly every living thing. The enzyme can be heated and cooled repeatedly.
In their experiments, Blankschien and Pretzer cloned, purified and altered glucokinase enzymes so they would attach to the gold nanoparticles. The enzyme/nanoparticle complexes were then suspended in a solution and tested for glucose degradation. When the solution was heated in bulk, they found the complexes became highly active at 176 degrees, as expected.
Then the complexes were encapsulated in a gel-like bead of calcium alginate, which helps keeps the heat in but is porous enough to allow enzymes to react with materials around it. Under bulk heating,
|Contact: David Ruth|