Researchers are reporting the construction of what they term "artificial molecules" and say they can use the technology to engineer a new generation of nanomaterials that control and direct the energy absorbed from light.
Including an antenna that can build itself.
Traditional antennas increase the amount of an electromagnetic wave – such as a radio frequency – that is absorbed, and then funnel that energy to a circuit. These nanoantennas instead increased the amount of light that is absorbed and funneled it to a single site within their molecule-like complexes. This concept is already used in nature in light harvesting antennas, constituents of leaves that make photosynthesis efficient.
"Nanotechnologists have for many years been captivated by quantum dots – particles of semiconductor that can absorb and emit light efficiently, and at custom-chosen wavelengths," explained co-author Shana Kelley, a Professor at University of Toronto. "What the community has lacked – until now – is a strategy to build higher-order structures, or complexes, out of multiple different types of quantum dots. This discovery fills that gap."
The team combined its expertise in DNA and in semiconductors to invent a generalized strategy to bind certain classes of nanoparticles to one another.
"The credit for this remarkable result actually goes to DNA: its high degree of specificity – its willingness to bind only to a complementary sequence – enabled us to build rationally-engineered, designer structures out of nanomaterials," said Ted Sargent, a Professor in The Edward S. Rogers Sr. Department of Electrical&Computer Engineering at the University of Toronto. "The amazing thing is that our antennas built themselves – we coated different classes of nanoparticles with selected sequences of DNA, combined the different families in one beaker, and nature took its course. The result is a beautiful new set of self-assembled materials with exciting properties."
"This is a terrific piece of work that demonstrates our growing ability to assemble precise structures, to tailor their properties, and to build in the capability to control these properties using external stimuli," noted Paul S. Weiss, Fred Kavli Chair in NanoSystems Sciences at UCLA and Director of the California NanoSystems Institute.
Kelley says that the concept published in today's Nature Nanotechnology paper is a broad one that goes beyond light antennas alone.
"What this work shows is that our capacity to manipulate materials at the nanoscale is limited only by human imagination. If semiconductor quantum dots are artificial atoms, then we have rationally synthesized artificial molecules from these versatile building blocks."
