MIT News – Page 14 – MIT Department of Chemistry

New light-powered catalysts could aid in manufacturing

by Anne Trafton | MIT News Office | May 27, 2022May 2, 2023

Chemical reactions that are driven by light offer a powerful tool for chemists who are designing new ways to manufacture pharmaceuticals and other useful compounds. Harnessing this light energy requires photoredox catalysts, which can absorb light and transfer the energy to a chemical reaction.

MIT chemists have now designed a new type of photoredox catalyst that could make it easier to incorporate light-driven reactions into manufacturing processes. Unlike most existing photoredox catalysts, the new class of materials is insoluble, so it can be used over and over again. Such catalysts could be used to coat tubing and perform chemical transformations on reactants as they flow through the tube.

“Being able to recycle the catalyst is one of the biggest challenges to overcome in terms of being able to use photoredox catalysis in manufacturing. We hope that by being able to do flow chemistry with an immobilized catalyst, we can provide a new way to do photoredox catalysis on larger scales,” says Richard Liu, an MIT postdoc and the joint lead author of the new study.

The new catalysts, which can be tuned to perform many different types of reactions, could also be incorporated into other materials including textiles or particles.

Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT, is the senior author of the paper, which appears today in Nature Communications. Sheng Guo, an MIT research scientist, and Shao-Xiong Lennon Luo, an MIT graduate student, are also authors of the paper.

Hybrid materials

Photoredox catalysts work by absorbing photons and then using that light energy to power a chemical reaction, analogous to how chlorophyll in plant cells absorbs energy from the sun and uses it to build sugar molecules.

Chemists have developed two main classes of photoredox catalysts, which are known as homogenous and heterogenous catalysts. Homogenous catalysts usually consist of organic dyes or light-absorbing metal complexes. These catalysts are easy to tune to perform a specific reaction, but the downside is that they dissolve in the solution where the reaction takes place. This means they can’t be easily removed and used again.

Heterogenous catalysts, on the other hand, are solid minerals or crystalline materials that form sheets or 3D structures. These materials do not dissolve, so they can be used more than once. However, these catalysts are more difficult to tune to achieve a desired reaction.

To combine the benefits of both of these types of catalysts, the researchers decided to embed the dyes that make up homogenous catalysts into a solid polymer. For this application, the researchers adapted a plastic-like polymer with tiny pores that they had previously developed for performing gas separations. In this study, the researchers demonstrated that they could incorporate about a dozen different homogenous catalysts into their new hybrid material, but they believe it could work more many more.

“These hybrid catalysts have the recyclability and durability of heterogeneous catalysts, but also the precise tunability of homogeneous catalysts,” Liu says. “You can incorporate the dye without losing its chemical activity, so, you can more or less pick from the tens of thousands of photoredox reactions that are already known and get an insoluble equivalent of the catalyst you need.”

The researchers found that incorporating the catalysts into polymers also helped them to become more efficient. One reason is that reactant molecules can be held in the polymer’s pores, ready to react. Additionally, light energy can easily travel along the polymer to find the waiting reactants.

“The new polymers bind molecules from solution and effectively preconcentrate them for reaction,” Swager says. “Also, the excited states can rapidly migrate throughout the polymer. The combined mobility of the excited state and partitioning of the reactants in the polymer make for faster and more efficient reactions than are possible in pure solution processes.”

Higher efficiency

The researchers also showed that they could tune the physical properties of the polymer backbone, including its thickness and porosity, based on what application they want to use the catalyst for.

As one example, they showed that they could make fluorinated polymers that would stick to fluorinated tubing, which is often used for continuous flow manufacturing. During this type of manufacturing, chemical reactants flow through a series of tubes while new ingredients are added, or other steps such as purification or separation are performed.

Currently, it is challenging to incorporate photoredox reactions into continuous flow processes because the catalysts are used up quickly, so they have to be continuously added to the solution. Incorporating the new MIT-designed catalysts into the tubing used for this kind of manufacturing could allow photoredox reactions to be performed during continuous flow. The tubing is clear, allowing light from an LED to reach the catalysts and activate them.

“The idea is to have the catalyst coating a tube, so you can flow your reaction through the tube while the catalyst stays put. In that way, you never get the catalyst ending up in the product, and you can also get a lot higher efficiency,” Liu says.

The catalysts could also be used to coat magnetic beads, making them easier to pull out of a solution once the reaction is finished, or to coat reaction vials or textiles. The researchers are now working on incorporating a wider variety of catalysts into their polymers, and on engineering the polymers to optimize them for different possible applications.

The research was funded by the National Science Foundation and the KAUST Sensor Initiative.

Five from MIT Named 2022 Knight-Hennessy Scholars

by Julia Mongo | Office of Distinguished Fellowships | May 11, 2022May 2, 2023

MIT seniors Desmond Edwards, Michelle Lee, and Syamantak Payra; graduate student Tomás Guarna; and Pranav Lalgudi ’21 have been honored by this year’s Knight-Hennessy Scholars program. They will head to Stanford University this fall to commence their doctoral programs.

Knight-Hennessy Scholars receive full funding for up to three years of graduate studies in any field at Stanford University. Fellows, who hail from countries around the world, also participate in the King Global Leadership Program, which aims to prepare them to become inspiring and visionary leaders who are committed to the greater good.

MIT students seeking more information on the Knight-Hennessy Scholar program can contact Kim Benard, associate dean of distinguished fellowships in Career Advising and Professional Development.

Desmond Edwards

Desmond Edwards, from St. Mary, Jamaica, will graduate this May from MIT with bachelor’s degrees in biological engineering and biology, with a minor in French. As a Knight-Hennessy Scholar, he will embark on a PhD in microbiology and immunology at Stanford School of Medicine. Edwards is interested in infectious diseases — both in understanding their underlying mechanisms and devising novel therapeutics to fulfill unmet patient needs. He further aspires to blend this research with public policy, outreach, and education. He has investigated and engineered host-pathogen interactions in MIT’s Lamason lab and has evaluated AAV gene therapies in Caltech’s Gradinaru lab and at Voyager Therapeutics. Edwards is the first undergraduate to serve as MIT Biotech Group co-president, is president of MIT’s chapter of the Tau Beta Pi Engineering Honour Society, was co-president of MIT’s Biological Engineering Undergraduate Board, and vice-captained MIT’s Quidditch Team. Edwards is a recipient of MIT’s Whitehead Prize in Biology, MIT’s Peter J Eloranta Summer Undergraduate Research Fellowship, a 2022 NSF Graduate Research Fellowship, and a 2021 Amgen Scholars Fellowship.

Tomás Guarna

Tomás Guarna, from Buenos Aires, Argentina, will pursue a PhD in Stanford’s Communication Department. He graduated from Universidad Torcuato Di Tella with a degree in social sciences, and then worked in the Office of the President of Argentina’s digital communications team. He is currently completing his SM in comparative media studies at MIT. Guarna aims to explore the role of technology in our civic life, understanding the relations between governments, technology companies, and civil society. Guarna was a Human Rights and Technology Fellow at the MIT Center for International Studies and a fellow at MIT’s Priscilla King Gray Public Service Center. He will be joining Stanford as a Knight-Hennessy Scholar and as a Stanford EDGE Fellow.

Pranav Lalgudi

Pranav Lalgudi, from San Jose, California, graduated from MIT in 2021 with a bachelor’s degree in biology, a minor in data science, and a concentration in philosophy. He will pursue a PhD in genetics at Stanford School of Medicine. Lalgudi is keen to answer fundamental questions in biology to improve our understanding of human health. At MIT, he uncovered how cells regulate metabolism in response to nutrients, processes which are disrupted in cancer and diabetes. He previously worked at Stanford, creating new tools for studying the genetic diversity of cancers. Lalgudi aspires to make academic research more collaborative, rigorous, and accessible. He is also passionate about addressing inequities in access to education and has worked at schools in Spain and Italy to develop more interactive STEM curricula for students. Lalgudi’s research has been accepted for publication in several peer-reviewed journals, including Nature, and he was awarded the NSF GRFP and NDSEG Fellowships.

Michelle Lee

Michelle Lee, from Seoul, South Korea, is an MIT senior majoring in chemistry. She will continue on at Stanford for a PhD in chemistry as a Knight-Hennessy Scholar and NSF GRFP Fellow. Lee’s goal is to understand and precisely manipulate the cellular machinery with synthetic molecules, which will open a door for novel, efficient, and affordable therapeutic strategies, especially in curing genetic diseases. At MIT, she designed a small molecule “switch” to CRISPR activity, which can precisely manipulate the activity of CRISPR-Cas protein, increasing its efficacy and reducing off-target effects. She also designed an affordable, rapid “mix-and-read” Covid-19 diagnostics tool for use in low- and middle-income countries, the work for which she was a first author of a publication. Lee has pushed to increase the accessibility of education by leading multiple educational enrichment programs.

Syamantak Payra

Syamantak Payra, from Friendswood, Texas, will graduate this spring from MIT with a bachelor’s degree in electrical engineering and computer science, and minors in public policy and in entrepreneurship and innovation. He will pursue a PhD in electrical engineering at Stanford School of Engineering as a Knight-Hennessy Scholar and Paul and Daisy Soros Fellow. Alongside creating new biomedical devices that can help improve daily life for patients worldwide, Payra aspires to shape American educational and scientific ecosystems to better empower upcoming generations. At MIT, he conducted research creating digital sensor fibers that have been woven into health-monitoring garments and next-generation spacesuits. He has organized and led literacy and STEM outreach programs benefiting a thousand underprivileged students nationwide. Payra earned multiple first-place awards at International Science and Engineering Fairs, placed ninth in the 2018 Regeneron Science Talent Search, was inducted into the National Gallery of America’s Young Inventors, and was an Astronaut Scholar, Coca-Cola Scholar, and U.S. Presidential Scholar.

MIT Research Slam showcases postdoc and PhD communication skills

by MIT Career Advising and Professional Development | May 2, 2022May 2, 2023

Can you tell the story of a complex research project in only three minutes? Could a presentation emerge from extreme time compression transformed like a diamond from coal? The MIT Research Slam Public Showcase on April 11 put these questions and more center stage as the four postdoc and five PhD student finalists competed for cash prizes.

The ability to compellingly pitch scientific research to a smart but non-specialized audience is a bankable skill central to success in any professional context, within academia or beyond — and the MIT Research Slam competition provides a supportive but competitive arena to hone this skill set. The Research Slam Public Showcase gives each participant 180 seconds to present their research, a format embraced by over 200 universities around the world for annual competitions. Aside from the thrill of competition, these events provide opportunities for trainees to develop and showcase their research communication skills.

During the weeks leading up to the event, participants joined training workshops on pitch content and delivery, and had the opportunity to work one-on-one with educators from Career Advising and Professional Development (CAPD), the Engineering Communication Labs, and the Writing and Communication Center, all of which co-sponsored and co-produced the event.

Simona Rosu, senior assistant director of postdoctoral career and professional development at CAPD, explains why this event is of particular value to PhD students and postdocs: “The ability to present their research accomplishments in a clear, compelling, and concise manner to non-experts is a key skill for the career development of PhD students and postdocs. It will help them put together strong job application materials; shine in interviews, job talks, and networking; and compete convincingly for funding opportunities, whether in academia or industry.”

The finalists included five PhD students — Leonard Boussioux, Juana De La O, Reuven “Beny” Falkovich, Olivia Kim, and Vrindaa Somjit — and four postdocs — Maria Kanelli, Jamie Karthein, Constantinos Katsimpouras, and Scott Odell. Topics ranged from superconducting qubits to melting protons.

A panel of accomplished judges gave feedback after each of the talks. Alisa Machalek, team lead and science communication and outreach at the National Institute of Arthritis, Musculoskeletal and Skin Disease; Jermey Matthews, senior acquisitions editor at MIT Press; and Babak Movassaghi, CEO of Vitruvia Holding, served as judges. Following the event, Movassaghi reflected, “What a joy to be part of this year’s MIT Research Slam as a judge. Kudos to all the passionate PhD candidates and postdocs mastering splendidly the challenge to explain their complex scientific research in only three minutes.”

At the end of the night, Jamie Karthein was the judges’ choice in the postdoc category, Scott Odell was the runner-up, and Jamie also won the hearts of the viewers and walked away with the Audience Choice award for postdocs. After the competition, Jamie reflected: “What I found to be most valuable was using a new communication technique to engage with a broad audience about my very fundamental physics research. I enjoyed the opportunity to engage with the audience during the Q&A session.”

In the PhD student class, Leonard Boussioux took the top honor as well as the Audience Choice prize, with Reuven “Beny” Falkovich close behind. Leonard summed up his Research Slam experience with enthusiasm: “Since I am interested in an academic position after my PhD, I found the Three Minute Thesis exercise highly insightful … I also realized that it is handy to be prepared to pitch anytime to any audience what I am doing with my time, and I saw myself naturally explaining what I do in the past few weeks.”

The first place finishers received a $600 cash prize, while runners up and Audience Choice winners each received $300.

A full list of showcase finalists and the titles of their talks is below. Video entries made public by the presenters will be available for viewing on the MIT Research Slam Youtube channel.

Research Slam organizers included Diana Chien, director of MIT School of Engineering Communication Lab; Simona Rosu, senior assistant director of postdoctoral career and professional development at CAPD; Elena Kallestinova, director of the MIT Writing and Communication Center; Alexis Boyer, assistant director of graduate career services at CAPD; Amanda Cornwall, associate director of graduate student professional development at CAPD; Viraat Goel, PhD student in biological engineering at MIT, Communication Lab Fellow, and representative of the Graduate Student Council External Affairs Board; and Pradeep Natarajan, PhD student in chemical engineering at MIT and Communication Lab Fellow. Prizes were sponsored by the MIT Career Advising and Professional Development.

Seven from MIT elected to American Academy of Arts and Sciences for 2022

by MIT News Office | April 28, 2022May 2, 2023

Seven MIT faculty members are among more than 250 leaders from academia, the arts, industry, public policy, and research elected to the American Academy of Arts and Sciences, the academy announced Thursday.

One of the nation’s most prestigious honorary societies, the academy is also a leading center for independent policy research. Members contribute to academy publications, as well as studies of science and technology policy, energy and global security, social policy and American institutions, the humanities and culture, and education.

Those elected from MIT this year are:

Alberto Abadie, professor of economics and associate director of the Institute for Data, Systems, and Society
Regina Barzilay, the School of Engineering Distinguished Professor for AI and Health
Roman Bezrukavnikov, professor of mathematics
Michale S. Fee, the Glen V. and Phyllis F. Dorflinger Professor and head of the Department of Brain and Cognitive Sciences
Dina Katabi, the Thuan and Nicole Pham Professor
Ronald T. Raines, the Roger and Georges Firmenich Professor of Natural Products Chemistry
Rebecca R. Saxe, the John W. Jarve Professor of Brain and Cognitive Sciences

“We are celebrating a depth of achievements in a breadth of areas,” says David Oxtoby, president of the American Academy. “These individuals excel in ways that excite us and inspire us at a time when recognizing excellence, commending expertise, and working toward the common good is absolutely essential to realizing a better future.”

Since its founding in 1780, the academy has elected leading thinkers from each generation, including George Washington and Benjamin Franklin in the 18th century, Maria Mitchell and Daniel Webster in the 19th century, and Toni Morrison and Albert Einstein in the 20th century. The current membership includes more than 250 Nobel and Pulitzer Prize winners.

Tackling chemical synthesis and advocacy

by Olivia Young | Office of Graduate Education | April 24, 2022May 2, 2023

Azin Saebi was born and raised in Iran, emigrating to the U.S. with her family at 18 after graduating from high school. Now a fifth-year graduate student in chemistry, Saebi never intended to stay permanently; she initially expected to go back to Iran to attend university. With that in mind, when leaving for the U.S., she only packed a bag with enough belongings for a couple of months and had even booked a return flight.

Her plans changed, however, as she began to recognize the opportunities available to her at American colleges, and that the best way to improve her English would be to stay in the U.S. Since she hadn’t taken the SAT or completed the requirements necessary to enter a traditional four-year college, she enrolled in community college with a plan to study biology and neuroscience, before transferring to UCLA.

In community college, Saebi discovered that she loved her undergraduate chemistry courses, so she joined an inorganic chemistry lab. “I really clicked more with the day-to-day lab experiments in chemistry rather than biology. It was fun and exciting how I could take material A and material B, mix them together in a controlled way and get this new molecule,” she says. To her, “biology seemed like more of a black box. With chemistry, I could check the progress at every step along the way.”

At MIT, Saebi is working at the intersection of chemistry and biology, designing novel strategies to synthesize proteins and to conjugate proteins together. Ultimately, these strategies have potential applications as antimicrobial compounds. In addition to her academic pursuits, she has devoted her time to advocating for diversity and inclusion initiatives and ensuring that students feel supported and heard within the chemistry department.

Lighting a “fire of chemistry”

When she started at Saddleback Community College, Saebi first chose to pursue a degree in neuroscience, with the intention of becoming a physician — a path influenced by watching “Grey’s Anatomy,” she jokes. Taking organic chemistry also sparked an interest in the interface between chemistry and biology. A biochemistry course at UCLA further cemented this passion, and she found that she excelled in the subject. “It was rather obvious that among neuroscience majors, [my reaction] to the class was an uncommon one, as it was generally considered a pretty irrelevant class to our core studies,” she says.

Saebi decided to double major in neuroscience and biochemistry. An inspiring professor, Alexander Spokonyny, encouraged her to join his inorganic chemistry lab. “He was the person that lit this fire of chemistry in me,” she says. Under his guidance, she synthesized small-molecule inhibitors to study cocaine addiction.

In the fall of senior year, Saebi knew that she “wanted to pursue this research thing” and that her interest in medicine had taken a back seat. She decided to enroll in UCLA’s 4+1 program to complete a master’s degree in biochemistry before applying to graduate programs in chemistry.

Unleashing novel proteins and “inner nerds”

When Saebi was admitted to MIT, she was determined to take advantage of the opportunity. “Growing up in Iran, I never imagined I would have the opportunity to go to a world-renowned university such as MIT,” she says. During the chemistry department’s visit weekend, where admitted students are invited to come to campus, she realized that students here “actually looked like me” in terms of the science they loved and the activities they were involved with.

Since beginning her PhD, Saebi’s aim has been to transition from organic chemistry to chemical biology. “Even though I enjoyed doing organic chemistry, I really wanted to pursue something with direct applications,” she notes. With this in mind, she decided to affiliate jointly with the labs of professor of chemistry Bradley Pentelute, and with Stephen Buchwald, the Camille Dreyfus Professor of Chemistry. The Buchwald lab focuses more on the organic chemistry methods, while the Pentelute lab focuses on peptides and emphasizes biological applications. “I really enjoyed making molecules, but I also knew that that alone would not keep me satisfied during the five years of my PhD,” Saebi explains. “I needed to make sure that I made something that I could apply to the biotechnology industry or to human health.”

The overall theme of Saebi’s work is developing novel chemical tools to modify biomolecules, specifically proteins. Her research has evolved in three distinct stages. First, she investigated a novel bioconjugation strategy, a chemical technique used to couple two proteins together. Then she worked on a method of synthesizing proteins via chemical ligation of amino acids, relying on chemical techniques to join the amino acids together instead of biological protein synthesis machinery. Most recently, Saebi has been combining these two tools, bioconjugation and chemical protein synthesis, to make antimicrobial compounds that specifically target and destroy Pseudomonas, a bacteria that can lead to serious infections in hospital patients.

Outside of lab, Saebi has served as a teaching assistant for course 5.07 (Introduction to Biological Chemistry). “It turned into a fun experience of helping [undergraduate] students unleash their inner nerd,” Saebi notes. “Given that I had really enjoyed my biochemistry classes back at UCLA, I really wanted to make sure that my students had the same experience.” She had to overcome her fear that, since English is her second language, students wouldn’t understand her explanations. Despite her initial hesitations, Saebi won the Department of Chemistry Outstanding Teaching Award in 2018. For her, that was “the cherry on top” of a rewarding teaching experience.

Sparking change for graduate students

In the past two years, Saebi has become an advocate for diversity, inclusion, and speaking up about challenges within MIT, serving as a member of the chemistry department’s Diversity, Equity and Inclusion Committee (DEIC) and co-president of Women+ in Chemistry (WIC+). Over time, Saebi has realized that one of her personal strengths is communicating student needs, a skill she has leveraged in these leadership roles.

“Graduate school is hard, and nothing is going to make it an easy-breezy experience because science is inherently hard. But, there are things that can make graduate school a bit easier and a more enjoyable experience. … Often we have the attitude that we will just suffer through it just because others before us have suffered through it, and that’s a problem” she says. Saebi is not content to just suffer through it; instead, she is determined to be the spark for change.

She is most proud of the holistic review of graduate admissions practices drafted by DEIC and implemented in chemistry admissions this year. The new practices evaluate candidates based on opportunities available to them, and their potential for growth, as well as their accomplishments.

She also serves with Resources for Easing Friction and Stress in the Chemistry Department (ChemREFS), which offers students an avenue to speak confidentially about their problems and to receive support. Learning about her peers’ struggles has informed her role in the DEIC, she says. “ChemREFS is helpful to me to ensure that I am actually representing the student body and the diversity of voices and perspectives.”

As she nears graduation, Saebi has been considering her next steps. She wants to continue solving problems in human health, and she understands that it can be a challenging and lengthy process translating academic research to new treatments for patients. “I want to be somewhere that I can see the impact of my work on patients’ lives and health care more immediately, and I’m grateful that my PhD at MIT has opened so many doors for me to explore science beyond academia,” she says.

“Spring-loaded” system pops phosphorus into molecular rings

by Anne Trafton | MIT News Office | April 21, 2022May 2, 2023

MIT chemists have devised a new chemical reaction that allows them to synthesize a phosphorus-containing ring, using a catalyst to add phosphorus to simple organic compounds called alkenes.

Their reaction, which yields a ring containing two carbon atoms and one phosphorus atom, can be performed at normal temperature and pressure, and makes use of a novel “spring-loaded” phosphorus-containing molecule that supplies the phosphorus atom.

“This is a rare example of a discovery of a new catalytic reaction, and it opens up a real wealth of new opportunities to do chemistry enabled by a reaction that never existed before,” says Christopher Cummins, the Henry Dreyfus Professor of Chemistry at MIT and the senior author of the study.

These phosphorus-containing rings could find uses as catalysts for other reactions, or as precursors for useful compounds such as pharmaceuticals, Cummins says.

MIT graduate student Martin-Louis Riu is the lead author of the paper, published this week in the Journal of the American Chemical Society. Former MIT research fellow Andre Eckhardt is also an author of the study.

Creating a ring

Organic compounds that contain double bonds between carbon atoms, also known as olefins or alkenes, are important precursors in many industrially useful chemical reactions. By breaking those carbon-carbon bonds and adding new atoms or groups of atoms, researchers can create a wide variety of new products.

As one example, chemists have previously devised ways to convert a carbon-carbon double bond into a three-membered ring by adding either another carbon atom, a nitrogen atom, or an oxygen atom. Such compounds can be found in plastics, pharmaceuticals, textiles, and other useful products.

However, because phosphorus is heavier than carbon, nitrogen, or oxygen, it has been difficult to find a way to incorporate it into olefins without using “brute force” methods that require harsh chemical conditions. The MIT team wanted to come up with a way to perform this reaction under mild conditions, using a catalyst to transfer a phosphinidene group — a phosphorus atom bound to an organic chemical group — to the olefin.

In order to achieve that, they needed a starting material that could act as a source of phosphinidene, but such compounds did not exist because direct analogues of those used for lighter elements such as carbon are unstable with phosphorus.

In a 2019 paper, Cummins’s lab developed one possible source, consisting of phosphinidene attached to a molecule that contains several hydrocarbon rings. Using this compound, they were able to synthesize a three-membered ring containing phosphorus, but the reaction required high temperatures and only worked with certain types of olefins.

In their new paper, the MIT team used a different source of phosphorus for the reaction — a compound that Cummins’ lab first synthesized in 2021. This molecule is a tetrahedron, a shape that inherently has a great deal of energy “strain,” much like a compressed spring, because of the small bond angles between the four atoms that form the tetrahedron.

This compound, called tri-tert-butylphosphatetrahedrane, has three vertices consisting of carbon atoms attached to a chemical group called tert-butyl, and one vertex consisting of a phosphorus atom with an unshared pair of electons. Under the right conditions, this strained molecule can be broken apart to release the phosphorus atom.

Efficient synthesis

Using this spring-loaded molecule, the researchers were able to use a nickel-containing catalyst to transfer phosphinidene to olefins to create three-membered rings. This reaction can be done at room temperature, with high yield of the desired product.

“All the stars aligned here in terms of us being able to synthesize a highly strained precursor that leads to room temperature reactivity and rapid catalysis,” Cummins says.

The researchers now plan to further investigate the mechanism of how this reaction occurs, which they believe is dependent on phosphinidene being temporarily transferred to the nickel catalyst complex. The catalyst then incorporates the phosphorus into the double bond of the olefin.

They also hope to explore the possibility of creating a variety of new compounds that include the phosphorus-containing ring, and to develop ways to control which of two possible mirror image versions are synthesized. Once these phosphorus-containing rings are formed, they can be opened up by adding additional molecules to create other useful compounds. Potential applications for these kinds of products include catalysts for other reactions, or components of pharmaceuticals that contain phosphorus.

The research was funded by the National Science Foundation and a Feodor Lynen Research Fellowship from the Alexander von Humboldt Foundation.

School of Science announces 2022 Infinite Mile Awards

by School of Science | April 15, 2022May 2, 2023

The MIT School of Science has announced the winners of the 2022 Infinite Mile Award. The selected staff members were nominated by their colleagues for going above and beyond in their roles at the Institute. Their outstanding contributions have made MIT a better place.

The following are the 2022 Infinite Mile Award winners in the School of Science:

• Christina Andujar, senior administrative assistant in the Department of Physics, was nominated by Peter Fisher, Edmund Bertschinger, and Matt Cubstead because Andujar “has gone far beyond her assigned role and duties to improve the lives of a great many students at MIT.”

• Monika Avello, an instructor in the Department of Biology, was nominated by Barbara Imperiali, Cathy Drennan, Graham Walker, Adam Martin, Lenny Guarente, David Des Marais, Seychelle Vos, and Jing-Ke Weng because Avello “was always meticulous in attention to detail and never hesitated when we threw out crazy ideas that might make the students gain something unique from the class — even if it gave her ever more things to do.”

• David Orenstein, director of communications in The Picower Institute for Learning and Memory, was nominated by Li-Huei Tsai, Mriganka Sur, Earl Miller, Gloria Choi, William Lawson, Asha Bhakar, Julie Pryor, Raleigh McElvery, and Julia Keller because Orenstein is “always willing to help out in whatever way is needed, whether as a part of a brainstorming session about any given topic, or lending a helping hand for an event or something else going on with the Institute. His dedication to the mission of the Picower Institute is unquestionable and it is evident in everything he does.”

• Dennis Porche, assistant to the department head in the Department of Mathematics, was nominated by Michel Goemans, Gigliola Staffilani, Michael Sipser, and Amanda Kuhl because Porche “has been amazingly dedicated to the well-being of the mathematics department at MIT, and cares tremendously about everything that goes on in the department. He will spend many hours making sure everything is perfect, nothing or no one is omitted, everyone is properly acknowledged, and everything goes smoothly.”

• Joshua Stone, administrative assistant in the Department of Biology, was nominated by Michael Laub, Hallie Dowling-Huppert, Alex Pike, Rebecca Chamberlain, and Janice Chang because Stone “has driven a movement to create an inclusive environment for staff within the biology department, implementing programs for welcoming new staff and establishing peer mentoring to increase the sense of inclusion within the department. These efforts are essential to shifting the culture and integrating pillars of DEI into the everyday operations of the biology department.”

• Sierra Vallin, academic administrator in the Department of Brain and Cognitive Sciences, was nominated by Michale Fee, Laura Schulz, Rebecca Saxe, Joshua McDermott, Mehrdad Jazayeri, Mark Harnett, Kate White, Laura Frawley, Kian Caplan, Di Kang, Halie Olson, Tobias Kaiser, and Julianne Ormerod because Vallin is “truly incredible” and “goes way above and beyond the call of duty to help students and other staff,” and for her “willingness to stand up for staff throughout our building, and to support our ongoing diversity efforts.”

• Shannon Wagner, senior administrative assistant in the Department of Chemistry, was nominated by Troy Van Voorhis, Stephen Buchwald, Jeremiah Johnson, Rick Danheiser, Richard Wilk, and Jennifer Weisman because Wagner “is someone who goes far above and beyond her usual call of duty. Her work has positively impacted many in the department including our students. She demonstrates an exceptional commitment to every aspect of her work and the staff with whom she works. Our department is a far better place with her in it.”

QS World University Rankings rates MIT No. 1 in 12 subjects for 2022

by MIT News Office | April 6, 2022May 2, 2023

MIT has earned a No. 1 spot in 12 subject areas, according to the QS World University Rankings for 2022, announced today.

The Institute received a No. 1 ranking in the following QS subject areas: Architecture/Built Environment; Chemistry; Computer Science and Information Systems; Chemical Engineering; Civil and Structural Engineering; Electrical and Electronic Engineering; Materials Science; Mechanical, Aeronautical, and Manufacturing Engineering; Linguistics; Mathematics; Physics and Astronomy; and Statistics and Operational Research.

MIT also placed second in two subject areas: Biological Sciences and Economics and Econometrics.

For 2022, universities were evaluated in 34 specific subjects and five broader subject areas. MIT was also ranked No. 1 in two of these broader subject areas: Natural Sciences, and Engineering and Technology.

Quacquarelli Symonds Limited subject rankings, published annually, are designed to help prospective students find the leading schools in their field of interest. Rankings are based on research quality and accomplishments, academic reputation, and graduate employment.

MIT has been ranked as the No. 1 university in the world by QS World University Rankings for 10 straight years.

Study reveals the dynamics of human milk production

by Anne Trafton | MIT News Office | April 5, 2022May 2, 2023

For the first time, MIT researchers have performed a large-scale, high-resolution study of the cells in breast milk, allowing them to track how these cells change over time in nursing mothers.

By analyzing human breast milk produced between three days and nearly two years after childbirth, the researchers were able to identify a variety of changes in gene expression in mammary gland cells. Some of these changes were linked to factors such as hormone levels, illness of the mother or baby, the mother starting birth control, and the baby starting daycare.

“We were able to take this really long view of lactation that other studies haven’t really done, and we showed that milk does change over the entire course of lactation, even after years of milk production,” says Brittany Goods, a former MIT postdoc who is now an assistant professor of engineering at Dartmouth College, and one of the senior authors of the study.

The researchers hope that their findings will lay the groundwork for more in-depth studies of how breast milk changes over time. Such studies could eventually yield new ways to boost mothers’ milk production or to improve the composition of infant formula.

Bonnie Berger, the Simons Professor of Mathematics at MIT and head of the Computation and Biology group at the Computer Science and Artificial Intelligence Laboratory (CSAIL), is a senior author of the study, as is Alex Shalek, an associate professor of chemistry at MIT and a member of the Institute for Medical Engineering and Science (IMES); the Koch Institute for Integrative Cancer Research; the Ragon Institute of MGH, MIT and Harvard; and the Broad Institute of Harvard and MIT.

MIT graduate student Sarah Nyquist is the lead author of the paper, which appears this week in the Proceedings of the National Academy of Sciences.

Cellular changes

Human mammary glands can produce more than a liter of milk in a day, for months or years after childbirth. Studying how mammary gland cells accomplish this feat has been difficult in humans because the tissue itself can’t be biopsied or otherwise accessed during lactation. However, recent studies have shown that breast milk contains many cells from the mammary gland, offering a noninvasive way to study these cells.

For this study, the MIT team collected breast milk samples from 15 nursing mothers. Each donor provided samples at multiple time points, ranging from three to 632 days after giving birth. The researchers also collected information about health and lifestyle changes that occurred throughout the lactation period.

The researchers isolated more than 48,000 cells from 50 samples and analyzed them using single-cell RNA-sequencing, a technology that can determine which genes are being expressed in a cell at a given moment in time. This analysis revealed 10 types of cells — a population of fibroblast cells, two types of epithelial cells, and seven types of immune cells.

More than half of the immune cells that they found were macrophages. These cells appear to express genes that help make the mammary gland more tolerant of the milk proteins that they are producing, so they don’t trigger an immune response. The researchers also found populations of B cells, T cells, and other immune cells, but their numbers were too small to do any in-depth studies of their functions.

By far the most abundant cells that they found were lactocytes, which are a type of epithelial cell. These cells expressed many genes for proteins that are found in breast milk, such as lactalbumin, as well as transporters needed to secrete milk proteins, micronutrients, fat, and other breast milk components.

Among the lactocytes, the researchers identified one cluster of cells that appears to be the primary producer of milk, and another that plays more of a structural role in the mammary gland. Each of these cell types could be divided into further subtypes, which the researchers hypothesize may be specialized for particular roles.

As time went on, the researchers found that the proportion of lactocytes involved in milk production went down, while the proportion involved in structural support went up. At the same time, genes involved in responding to the hormone prolactin became more active in the milk-producing lactocytes but dropped off in structural lactocytes. The researchers theorize that these changes may be related to the changing nutritional needs of infants as they grow.

“This study, along with some other studies that are out there, paves the way for mapping out and better understanding some of the pathways that these cells use to accomplish the tremendous amount of work that they do,” Goods says.

Milk composition

The researchers also found links between the composition of cells in breast milk and events such as babies starting to go to daycare, starting formula, or the mother starting to use hormonal birth control.

“There are clearly changes in the composition of breast milk that are related to these lifestyle and health changes, such as infant illness or maternal hormonal birth control,” Nyquist says. “These changes in lactation don’t necessarily have a positive or negative impact on anyone’s health, but they do occur and they may lead us to insights into how mammary epithelial cells are producing milk and the types of components that they may be producing.”

The researchers now hope to do larger studies that could help them find stronger links between environmental factors and milk composition, and also discover more about how milk naturally changes over time. This could eventually help scientists devise better infant formulas or create formulas adapted to different stages of infancy. The researchers also hope to find ways to help nursing mothers boost their milk production or slow it down when babies are being weaned.

Other follow-up studies may explore how pumping affects milk composition and breast health, or how to prevent conditions such as mastitis.

“By building this really high-resolution understanding of lactational diversity over time, it gives us a way to not only understand lactation, but it also gives us a set of data and tools to be able to engineer better solutions to improve the quality of life of mothers, specifically when they’re nursing,” Goods says.

The research was funded by the Koch Institute Support (core) Grant from the National Cancer Institute, the National Institutes of Health, a National Research Service Award postdoctoral fellowship, the Beckman Young Investigator Program, a Sloan Fellowship in Chemistry, the Charles E. Reed Faculty Initiative, a National Science Foundation Graduate Research Fellowship, an MIT-GSK Gertrude B. Elion Postdoctoral Fellowship, the Columbia University Office of the Provost, the Weizmann Institute of Science National Postdoctoral Award Program for Advancing Women in Science, the International Society for Research in Human Milk and Lactation Trainee Bridge Fund, and the Human Frontier Science Program.

Chemical reactions for the energy transition

by Nancy W. Stauffer | MIT Energy Initiative | April 4, 2022May 2, 2023

One challenge in decarbonizing the energy system is knowing how to deal with new types of fuels. Traditional fuels such as natural gas and oil can be combined with other materials and then heated to high temperatures so they chemically react to produce other useful fuels or substances, or even energy to do work. But new materials such as biofuels can’t take as much heat without breaking down.

A key ingredient in such chemical reactions is a specially designed solid catalyst that is added to encourage the reaction to happen but isn’t itself consumed in the process. With traditional materials, the solid catalyst typically interacts with a gas; but with fuels derived from biomass, for example, the catalyst must work with a liquid — a special challenge for those who design catalysts.

For nearly a decade, Yogesh Surendranath, an associate professor of chemistry at MIT, has been focusing on chemical reactions between solid catalysts and liquids, but in a different situation: rather than using heat to drive reactions, he and his team input electricity from a battery or a renewable source such as wind or solar to give chemically inactive molecules more energy so they react. And key to their research is designing and fabricating solid catalysts that work well for reactions involving liquids.

Recognizing the need to use biomass to develop sustainable liquid fuels, Surendranath wondered whether he and his team could take the principles they have learned about designing catalysts to drive liquid-solid reactions with electricity and apply them to reactions that occur at liquid-solid interfaces without any input of electricity.

To their surprise, they found that their knowledge is directly relevant. Why? “What we found — amazingly — is that even when you don’t hook up wires to your catalyst, there are tiny internal ‘wires’ that do the reaction,” says Surendranath. “So, reactions that people generally think operate without any flow of current actually do involve electrons shuttling from one place to another.” And that means that Surendranath and his team can bring the powerful techniques of electrochemistry to bear on the problem of designing catalysts for sustainable fuels.

A novel hypothesis

Their work has focused on a class of chemical reactions important in the energy transition that involve adding oxygen to small organic (carbon-containing) molecules such as ethanol, methanol, and formic acid. The conventional assumption is that the reactant and oxygen chemically react to form the product plus water. And a solid catalyst — often a combination of metals — is present to provide sites on which the reactant and oxygen can interact.

But Surendranath proposed a different view of what’s going on. In the usual setup, two catalysts, each one composed of many nanoparticles, are mounted on a conductive carbon substrate and submerged in water. In that arrangement, negatively charged electrons can flow easily through the carbon, while positively charged protons can flow easily through water.

Surendranath’s hypothesis was that the conversion of reactant to product progresses by means of two separate “half-reactions” on the two catalysts. On one catalyst, the reactant turns into a product, in the process sending electrons into the carbon substrate and protons into the water. Those electrons and protons are picked up by the other catalyst, where they drive the oxygen-to-water conversion. So, instead of a single reaction, two separate but coordinated half-reactions together achieve the net conversion of reactant to product.

As a result, the overall reaction doesn’t actually involve any net electron production or consumption. It is a standard “thermal” reaction resulting from the energy in the molecules and maybe some added heat. The conventional approach to designing a catalyst for such a reaction would focus on increasing the rate of that reactant-to-product conversion. And the best catalyst for that kind of reaction could turn out to be, say, gold or palladium or some other expensive precious metal.

However, if that reaction actually involves two half-reactions, as Surendranath proposed, there is a flow of electrical charge (the electrons and protons) between them. So Surendranath and others in the field could instead use techniques of electrochemistry to design not a single catalyst for the overall reaction but rather two separate catalysts — one to speed up one half-reaction and one to speed up the other half-reaction. “That means we don’t have to design one catalyst to do all the heavy lifting of speeding up the entire reaction,” says Surendranath. “We might be able to pair up two low-cost, earth-abundant catalysts, each of which does half of the reaction well, and together they carry out the overall transformation quickly and efficiently.”

But there’s one more consideration: Electrons can flow through the entire catalyst composite, which encompasses the catalyst particle(s) and the carbon substrate. For the chemical conversion to happen as quickly as possible, the rate at which electrons are put into the catalyst composite must exactly match the rate at which they are taken out. Focusing on just the electrons, if the reaction-to-product conversion on the first catalyst sends the same number of electrons per second into the “bath of electrons” in the catalyst composite as the oxygen-to-water conversion on the second catalyst takes out, the two half-reactions will be balanced, and the electron flow — and the rate of the combined reaction — will be fast. The trick is to find good catalysts for each of the half-reactions that are perfectly matched in terms of electrons in and electrons out.

“A good catalyst or pair of catalysts can maintain an electrical potential — essentially a voltage — at which both half-reactions are fast and are balanced,” says Jaeyune Ryu PhD ’21, a former member of the Surendranath lab and lead author of the study; Ryu is now a postdoc at Harvard University. “The rates of the reactions are equal, and the voltage in the catalyst composite won’t change during the overall thermal reaction.”

Drawing on electrochemistry

Based on their new understanding, Surendranath, Ryu, and their colleagues turned to electrochemistry techniques to identify a good catalyst for each half-reaction that would also pair up to work well together. Their analytical framework for guiding catalyst development for systems that combine two half-reactions is based on a theory that has been used to understand corrosion for almost 100 years, but has rarely been applied to understand or design catalysts for reactions involving small molecules important for the energy transition.

Key to their work is a potentiostat, a type of voltmeter that can either passively measure the voltage of a system or actively change the voltage to cause a reaction to occur. In their experiments, Surendranath and his team use the potentiostat to measure the voltage of the catalyst in real time, monitoring how it changes millisecond to millisecond. They then correlate those voltage measurements with simultaneous but separate measurements of the overall rate of catalysis to understand the reaction pathway.

For their study of the conversion of small, energy-related molecules, they first tested a series of catalysts to find good ones for each half-reaction — one to convert the reactant to product, producing electrons and protons, and another to convert the oxygen to water, consuming electrons and protons. In each case, a promising candidate would yield a rapid reaction — that is, a fast flow of electrons and protons out or in.

To help identify an effective catalyst for performing the first half-reaction, the researchers used their potentiostat to input carefully controlled voltages and measured the resulting current that flowed through the catalyst. A good catalyst will generate lots of current for little applied voltage; a poor catalyst will require high applied voltage to get the same amount of current. The team then followed the same procedure to identify a good catalyst for the second half-reaction.

To expedite the overall reaction, the researchers needed to find two catalysts that matched well — where the amount of current at a given applied voltage was high for each of them, ensuring that as one produced a rapid flow of electrons and protons, the other one consumed them at the same rate.

To test promising pairs, the researchers used the potentiostat to measure the voltage of the catalyst composite during net catalysis — not changing the voltage as before, but now just measuring it from tiny samples. In each test, the voltage will naturally settle at a certain level, and the goal is for that to happen when the rate of both reactions is high.

Validating their hypothesis and looking ahead

By testing the two half-reactions, the researchers could measure how the reaction rate for each one varied with changes in the applied voltage. From those measurements, they could predict the voltage at which the full reaction would proceed fastest. Measurements of the full reaction matched their predictions, supporting their hypothesis.

The team’s novel approach of using electrochemistry techniques to examine reactions thought to be strictly thermal in nature provides new insights into the detailed steps by which those reactions occur and therefore into how to design catalysts to speed them up. “We can now use a divide-and-conquer strategy,” says Ryu. “We know that the net thermal reaction in our study happens through two ‘hidden’ but coupled half-reactions, so we can aim to optimize one half-reaction at a time” — possibly using low-cost catalyst materials for one or both.

Adds Surendranath, “One of the things that we’re excited about in this study is that the result is not final in and of itself. It has really seeded a brand-new thrust area in our research program, including new ways to design catalysts for the production and transformation of renewable fuels and chemicals.”

This research was supported primarily by the Air Force Office of Scientific Research. Jaeyune Ryu PhD ’21 was supported by a Samsung Scholarship. Additional support was provided by a National Science Foundation Graduate Research Fellowship.

This article appears in the Autumn 2021 issue of Energy Futures, the magazine of the MIT Energy Initiative.