Winners of the 2023 Nobel Prize in Chemistry on the screen: scientists Moungi Bawendi, Louis Brus and Alexi Ekimov, for discovery and synthesis of quantum dots.
| Photo Credit: AP/Claudio Bresciani

The story so far: The 2023 Nobel Prize in chemistry was awarded to Moungi G. Bawendi, Louis E. Brus and Alexei I. Ekimov on Wednesday for the discovery and synthesis of quantum dots. These nanoparticles have wide-ranging applications across fields like electronics, advanced surgery, and quantum computing.

The prize itself was embroiled in some controversy earlier when the names of winners were reportedly leaked to a Swedish newspaper. But Johan Åqvist, the chair of the deciding committee, said the decision hadn’t been final at the time. “There was a press release sent out for still unknown reasons. We deeply regret that this happened. The important thing is that it did not affect the recipients in any way,” he was quoted as saying by The Guardian.

What are quantum dots?

Quantum dots are particles that are a few nanometres wide. They exhibit unique optical properties due to their small physical size. Their structure and atomic composition are the same as bulk materials, but the properties of the latter don’t depend on their size.

In fact ,the properties of quantum dots can be changed by changing their size.

At the scale of nanometres, materials and particles are capable of new, size-dependent properties because quantum physical forces start to dominate. At the macroscopic scale, on the other hand, like in our day to day lives, gravity and the rules of classical physics dominate.

By the 1970s, physicists knew that the optical properties of glass could be changed by adding a small amount of another element, like gold, silver, cadmium, sulphur, or selenium. They also knew how or why some of these changes could occur, but quantum dots as such hadn’t been synthesised yet.

The Nobel-winning research

In the early 1980s, Dr. Ekimov succeeded in creating size-dependent quantum effects in coloured glass. From 1979, he studied the properties of glasses that were tinted with copper chloride, heated to a high temperature, and then cooled. He found that different ways of preparing this glass led to it absorbing light differently. This happened because the copper chloride formed tiny crystals, and that crystals of different sizes—depending on the preparation process—interacted with light differently.

In 1983, Dr. Brus and his colleagues went a step ahead and prepared similar crystals in a liquid solution, rather than in a glass. This allowed the researchers to better manipulate and study the crystals. These crystals also interacted with light differently depending on small variations in their size.

Finally, in 1993, Dr. Bawendi and his coworkers developed a technique to make these peculiar crystals—i.e. the quantum dots—of well-defined sizes and with high optical quality. This process began by injecting some substance (of which the dot would be made) into a hot solvent and then heating the solution. Nanocrystals automatically began to take shape, and larger particles formed when the solution was heated for longer. The solvent also ensured that the crystals had a smooth outer surface.

This method was quite easy, which meant many scientists could use it to make quantum dots that they required and study them.

Modern-day applications

Today, one of the simplest applications of quantum dots is to light computer monitors and television screens. Blue LEDs behind the screen excite these dots, causing them to emit light of different colours. Combining these colours gives rise to even more colours as well as brightness.

Nanoscale-sized quantum dots are also used to map biological tissues by biochemists.

Quantum dots are also used in photovoltaic cells to improve the absorption and efficiency in converting solar light into electricity.

Certain cancer treatments use quantum dots for targeted drug delivery and other therapeutic measures. This has wider applications in the field of nanomedicine too.

Quantum dots can be used as security markers on currency and documents as an anti-counterfeit measure. Broadly, they can be used as fluorescent markers to tag and track objects.

Dr. Drew Weissman arrives for the Ninth Breakthrough Prize Ceremony at the Academy Museum of Motion Pictures in Los Angeles, California, U.S., April 15, 2023.
| Photo Credit: Reuters

Drew Weissman’s decades of research into mRNA technology paved the way for Covid-19 vaccines, finally earning a Nobel prize for the physician-scientist.

The 64-year-old University of Pennsylvania immunologist, who won the Nobel Medicine Prize along with long-time collaborator Katalin Kariko on Monday, is far from done.

His next quests include, among others, developing a vaccine against all future coronaviruses.

“There have been three (coronavirus) pandemics or epidemics in the past 20 years,” Weissman told AFP recently, referring to the original SARS virus, MERS and Covid-19.

“You have to assume there’s going to be more, and our idea was that we could wait for the next coronavirus epidemic or pandemic, and then spend a year and a half making a vaccine. Or we could make one now.”

Twin breakthroughs

The world is now aware of the elegance of the mRNA (messenger ribonucleic acid) vaccines, that deliver genetic instructions to cells telling them to recreate the spike protein of the coronavirus, in order to trigger effective antibodies when they encounter the real thing.

But back when Weissman teamed up with Kariko in the 1990s, the research was considered a scientific dead-end, and working with DNA was considered a more promising avenue.

“We started working together in 1998, and that was without much funding and without much in the way of publications,” he said.

In 2005, the pair found a way to alter synthetic RNA to stop it from causing a massive inflammatory response found in animal experiments.

“Just before our paper was published, I said ‘Our phones are going to ring off the hook,'” he recalls.

“We sat there staring at our phones for five years, and they never rang!”

With a second big breakthrough in 2015, they found a new way to deliver the particles safely and effectively to their target cells, using a fatty coating called “lipid nanoparticles.”

Both developments are part of the Pfizer and Moderna Covid-19 vaccines today.

Helping people

Weissman grew up in Lexington, Massachusetts.

His father and mother, both since retired, were an engineer and dental hygienist, respectively.

“When I was five years old, I was diagnosed as a type-one diabetic, and back then it was testing urine and taking insulin shots a few times a day,” he recalled, and this motivated him to pursue science.

He was educated at Brandeis University and completed an MD-Phd program in immunology at Boston University.

As a young fellow at the National Institutes of Health, he worked for several years in Anthony Fauci’s lab on HIV research, before finally arriving at his long-time home Penn.

Weissman was a practicing doctor until a few years ago, and says it brings him great joy that his invention has helped save millions of lives.

“I’m a clinician scientist, my dream since starting college and medical school was to make something that helps people. I think I can say that I’ve done that. So I am incredibly happy,” he said.

Beyond vaccines, mRNA technology is also being heralded for its potential across medicine.

Weissman’s team is working on using RNA to develop a single-injection gene therapy to overcome the defect that causes sickle cell anemia, a genetic blood disease that 200,000 babies are born with in Africa every year.

Significant technical challenges remain to ensure the treatment is able to correctly edit genes and is safe, but the researchers are hopeful.

Bone marrow transplant, an expensive treatment with serious risks, is currently the only cure.

Hungarian biochemist Katalin Kariko attends the Semmelweis Ignac Award in Budapest, Hungary, May 25, 2021. Two scientists have won the Nobel Prize in medicine on Monday, Oct. 2, 2023 for discoveries that enabled the development of mRNA vaccines against COVID-19. The award was given to Katalin Karikó and Drew Weissman. Karikó is a professor at Sagan’s University in Hungary and an adjunct professor at the University of Pennsylvania.
| Photo Credit: AP

Hungarian-American biochemist Katalin Karikó has become the newest Laureate to join the ranks of the numbered women who have won arguably the most prestigious award.

The 68-year-old biochemist and her colleague Drew Weissman were honoured with the Prize for “discoveries concerning nucleoside base modification that enabled the development of effective mRNA vaccines against COVID-19.”

From 1901 to 2023, the Nobel Prize has been awarded to women 62 times. Marie Curie is still the only woman to have won the Prize twice–once in 1903 for Physics and once in 1911 for Chemistry. 

Also Read | A look at how more women are making a mark in Science

The winners of the Nobel Prize have historically been white men. However, in an effort to be more inclusive, five years ago, the head of the Royal Swedish Academy of Sciences asked nominating bodies to make sure they don’t overlook “women or people of other ethnicities or nationalities in their nominations.”

While more women have won the Prize, the number of female winners in Physics, Chemistry, Medicine and Economics is still very low. This year’s winner, Dr. Karikó, has become the 13th woman to win the Nobel Prize in Medicine. Only four women have been granted the Prize in Physics while eight women have won the Prize in Chemistry. The Prize for Economic Sciences has been awarded to only two women.

In the early years of the Nobel Prizes, the underrepresentation of diverse winners was often attributed to the limited diversity within the scientific community. However critics today argue that the selection committees need to do a better job of recognising breakthroughs achieved by female scientists and researchers from regions beyond Europe and North America.