Working on tiny dots that illuminate TV screens and assist physicians in seeing blood vessels feeding tumors has earned three scientists the 2023 Nobel Prize in chemistry.
Moungi Bawendi, Louis Brus, and Alexei Ekimov received equal prizes from the Royal Swedish Academy of Sciences on October 4 for their contributions to discovering and synthesizing quantum dots.
Heiner Linke, a member of the Nobel committee, described quantum dots as an emerging class of materials distinct from molecules. Simply by altering their size – just a few billionths of an inch wide – scientists can alter the properties that arise due to quantum mechanics (SN: 6/29/15).
That principle also holds for color: to produce new hues using molecules, Linke suggested selecting new molecules with distinct sets of atoms arranged differently; but quantum dots with various hues all feature identical arrangements of atoms – their only variation coming in particle size differences.
Light illuminates quantum dots, invigorating their electrons until they release that energy as fluorescent light. As more electrons are activated within these tiny dots, their wave function becomes compressed further boosting energy to form blue spots while larger dots show as red ones.
Dots made from different materials may produce light waves of slightly differing wavelengths, according to Jean-Marc Pecourt of CAS, an arm of the American Chemical Society. Quantum dots typically consist of semiconductor materials like graphene, selenite, or metal sulfides; by changing materials or their sizes accordingly chemists can manipulate their properties for various uses.
Nautilus first predicted nearly one century ago that nanoparticle size can alter their properties, yet at first, this theory seemed outlandishly impossible to recreate in reality. Researchers would need a perfectly crystalline material and precise control over nanomaterial size – perhaps by layering individual atoms atomic by atomic.
Ekimov and Brus independently demonstrated this could be done during the early 1980s. Ekimov of Nanocrystals Technology Inc. in Briarcliff Manor New York demonstrated this by adding copper chloride to glass to produce tiny crystals; the color of this glass then corresponded with size; this discovery led Brus of Columbia University to show similar links between size and color for nanoparticles floating free in solution or gaseous compounds (SN: 10/3/92).
These discoveries sparked tremendous enthusiasm to harness tiny dots for various uses; however, to do this effectively would require being able to control particle sizes precisely enough in manufacturing them.
Bawendi of MIT later developed an approach for precisely controlling crystal growth rates in solution, stopping their expansion at exactly desired sizes. His solution involved injecting chemical reagents that instantaneously formed tiny crystals before promptly altering temperature settings to stop their spread.
“I was profoundly honored and amazed to receive such news this morning,” Bawendi declared during an MIT news conference on October 4th, “and am especially honored that Lou Brus was my postdoctoral mentor from whom I learned so much; his scholarship and mentoring style has served me well here at MIT.”
Bawendi first got interested in quantum dots after meeting Brus at Nokia Bell Labs’ Murray Hill facility, New Jersey location. These researchers needed high-quality quantum dots in order to explore nanoparticle physics; therefore it took years of trial and error for him to figure out the approach he explained.
Bawendi’s method for producing quantum dots ushered in an exciting era for nanoparticles. Quantum dots allow precise control over LED light color settings and dramatically improved efficiency; also used as fluorescent dot markers can help surgeons detect hard-to-see cancerous tissues more accurately (SN: 8/3/04). Their capacity to absorb different wavelengths could allow manufacturers to build customized solar cells optimized for different lighting conditions or possibly used for building quantum computers according to Pecourt (SN: 2/14/18).
Biomedical engineer and chemist Warren Chan from the University of Toronto believes this prize is well deserved, saying those responsible have laid down its foundation. “I am really pleased that our field is finally receiving recognition for having changed so many fields not just within quantum dots.”
One of the first applications came during Chan and colleagues’ work using quantum dots in lab cells as tags in the late 1990s, according to him. Chan noted that surface modifications used for integrating quantum dots could also be modified for other nanoparticle types and used with those.
Chan points out that the Nobel committee considers not just past contributions, but also their potential long-term effects when awarding Nobel prizes. Tuning nanoparticles by altering the size or surface properties opens a variety of unexplored doors – for instance using quantum dots as diagnostic tests against HIV, influenza, and Hepatitis B infection among others.
“I was absolutely delighted to witness this,” states Judith Giordan, president of the American Chemical Society. “Three people were recognized who took this technology from its infancy right through to creation and manufacture.”
Recently, it was widely anticipated that the development of mRNA vaccines might receive consideration for the 2023 Chemistry Nobel Prize; instead, it received it (SN: 10/2/23)!
Giordan notes, “Chemistry may get an unfair reputation; but here are two magnificent examples that demonstrate its usefulness for solving issues in society.”
Three winners will share in an 11 million Swedish Krona prize pool, equivalent to about $1 Million USD.