Author: MIT News

Researchers develop a new source of quantum light

by David L. Chandler | MIT News Office |

Using novel materials that have been widely studied as potential new solar photovoltaics, researchers at MIT have shown that nanoparticles of these materials can emit a stream of single, identical photons.

While the work is currently a fundamental discovery of these materials’ capabilities, it might ultimately pave the way to new optically based quantum computers, as well as possible quantum teleportation devices for communication, the researchers say. The results appear today in the journal Nature Photonics, in a paper by graduate student Alexander Kaplan, professor of chemistry Moungi Bawendi, and six others at MIT.

Most concepts for quantum computing use ultracold atoms or the spins of individual electrons to act as the quantum bits, or qubits, that form the basis of such devices. But about two decades ago some researchers proposed the idea of using light instead of physical objects as the basic qubit units. Among other advantages, this would eliminate the need for complex and expensive equipment to control the qubits and enter and extract data from them. Instead, ordinary mirrors and optical detectors would be all that was needed.

“With these qubit-like photons,” Kaplan explains, “with just ‘household’ linear optics, you can build a quantum computer, provided you have appropriately prepared photons.”

The preparation of those photons is the key thing. Each photon has to precisely match the quantum characteristics of the one before, and so on. Once that perfect matching is achieved, “the really big paradigm shift then is changing from the need for very fancy optics, very fancy equipment, to needing just simple equipment. The thing that needs to be special is the light itself.”

Then, Bawendi explains, they take these single photons that are identical and indistinguishable from each other, and they interact them with each other. That indistinguishability is crucial: If you have two photons, and “everything is the same about them, and you can’t say number one and number two, you can’t keep track of them that way. That’s what allows them to interact in certain ways that are nonclassical.”

Kaplan says that “if we want the photon to have this very specific property, of being very well-defined in energy, polarization, spatial mode, time, all of the things that we can encode quantum mechanically, we need the source to be very well-defined quantum mechanically as well.”

The source they ended up using is a form of lead-halite perovskite nanoparticles. Thin films of lead-halide perovskites are being widely pursued as potential next-generation photovoltaics, among other things, because they could be much more lightweight and easier to process than today’s standard silicon-based photovoltaics. In nanoparticle form, lead-halide perovskites are notable for their blindingly fast cryogenic radiative rate, which sets them apart from other colloidal semiconductor nanoparticles. The faster the light is emitted, the more likely the output will have a well-defined wavefunction. The fast radiative rates thus uniquely position lead-halide perovskite nanoparticles to emit quantum light.

To test that the photons they generate really do have this indistinguishable property, a standard test is to detect a specific kind of interference between two photons, known as Hong-Ou-Mandel interference. This phenomenon is central to a lot of quantum-based technologies, Kaplan says, and therefore demonstrating its presence “has been a hallmark for confirming that a photon source can be used for these purposes.”

Very few materials can emit light that meets this test, he says. “They pretty much can be listed on one hand.” While their new source is not yet perfect, producing the HOM interference only about half the time, the other sources have significant issues with achieving scalability. “The reason other sources are coherent is they’re made with the purest materials, and they’re made individually one by one, atom by atom. So, there’s very poor scalability and very poor reproducibility,” Kaplan says.

By contrast, the perovskite nanoparticles are made in a solution and simply deposited on a substrate material. “We’re basically just spinning them onto a surface, in this case just a regular glass surface,” Kaplan says. “And we’re seeing them undergo this behavior that previously was seen only under the most stringent of preparation conditions.”

So, even though these materials may not yet be perfect, “They’re very scalable, we can make a lot of them. and they’re currently very unoptimized. We can integrate them into devices, and we can further improve them,” Kaplan says.

At this stage, he says, this work is “a very interesting fundamental discovery,” showing the capabilities of these materials. “The importance of the work is that hopefully it can encourage people to look into how to further enhance these in various device architectures.”

And, Bawendi adds, by integrating these emitters into reflective systems called optical cavities, as has already been done with the other sources, “we have full confidence that integrating them into an optical cavity will bring their properties up to the level of the competition.”

The research team included Chantalle Krajewska, Andrew Proppe, Weiwei Sun, Tara Sverko, David Berkinsky, and Hendrik Utzat. The work was supported by the U.S. Department of Energy and the Natural Sciences and Engineering Research Council of Canada.

Charlie Farquhar: Forger of chemical and social bonds

by Laura Rosado | MIT News correspondent |

Charlie Farquhar entered college intending to major in history, but quickly pivoted after taking an introductory chemistry course and becoming fascinated by chemistry’s biomedical applications.

“I’m interested in how these small chemicals and molecular interactions can make really large-scale changes in the body,” says Farquhar, noting that the practice of chemistry itself is similar. As a scientist, “I can be a part of that signaling cascade that makes system-wide change,” they add.

Now a fifth-year graduate student in the lab of chemistry professor Bradley Pentelute, Farquhar’s research focuses on targeted drug delivery, to ensure drugs are affecting the intended location within the body.

In one of their two main projects, Farquhar is developing a peptide that binds to a protein over-expressed in brain tumor cells. The peptide is also designed to enter the cells to deliver a chemotherapy drug to the tumor, helping to decrease side effects from off-target interactions and lower cost by requiring less of the drug for an effective treatment.

The second project operates with a similar principle but aims to improve treatment for muscular dystrophy. The Pentelute Lab is working with a Cambridge, Massachusetts, company that has developed the only FDA-approved treatment for muscular dystrophy, but the treatment currently requires frequent high dosages to be effective. By developing a targeting peptide that binds and enters muscle cells, the project aims to reduce wasted product and save cost.

Farquhar was drawn to these projects because of their tangible impacts on human health. They also apply this ethos outside of their lab work. Farquhar is passionate about equal access to education and has spearheaded several initiatives within the chemistry department in pursuit of this goal.

As a teaching assistant for undergraduate chemistry courses, Farquhar relished the opportunity for direct mentorship with their students and the relationships they formed. Their ability to connect with their students earned them a departmental teaching award as a first-year graduate student in 2019.

Farquhar also applies that mentality to the Pentelute Lab, fondly describing their “small army of children” — the group of junior graduate students they have trained on different instruments or lent a helpful ear to talk through project ideas.

“I especially love the people,” Farquhar says of their labmates. “Even when the science isn’t going well, l still look forward to going to work every day because I love everyone in my lab. And I’ve put a lot of work into making sure the lab has a good and healthy culture.”

The same applies to their work within the Department of Chemistry. Farquhar is currently the president of the Chemistry Alliance of Diversity and Inclusion, and an active member of the Chemistry Graduate Student Committee and Women+ in Chemistry groups. Alongside classmates, they have organized programming for #ShutDownChem, derived from the #ShutDownSTEM movement, every June since 2020.

“Everyone should be responsible for things like participating in DEI and working toward greater equality and inclusion,” says Farquhar. “We sometimes put an undue burden on students from underrepresented groups in terms of what we’re actually asking them to do. We should all share in this work, and then it’s not a burden at all.”

Farquhar says they’re most proud of the work they’ve done encouraging future members of the department, both graduate students and faculty members. They helped start a program to provide mentorship during the graduate student application process, guidance they wish they’d had during their own experience applying. Farquhar was also involved in organizing the Future Faculty in Chemistry Symposium, which invites postdocs to give a talk at MIT and participate in workshops with current faculty members to strengthen their job applications. The symposium specifically recruits postdocs from underrepresented groups and those who’ve put a lot of time into diversity, equity, and inclusion efforts alongside their career.

“We’re trying to help boost these people when they’re applying for faculty jobs around the country,” says Farquhar. “We’re boosting the applications of people who have put a lot of time and thought and effort into DEI, which are both the kind of professors we’d like to hire in the future and the kind of people who should be acknowledged.”

After finishing their program, Farquhar plans to continue with drug delivery research in the hopes of bringing down costs for consumers. For now, they’re focused on enjoying their current work and the people it allows them to interact with.

“One of my favorite things about research in my lab in particular is collaboration,” says Farquhar. “Having the opportunity to work with other scientists, especially internationally, I think that’s been something really fun about doing science. Whether it’s mentorship or just running a small part of somebody else’s larger paper, it’s very cool to be part of this system that all works together.”

Tiny diamond rotor could improve protein studies

by David L. Chandler | MIT News Office |

Many of the biological materials that researchers are most interested in studying, including those associated with major diseases, don’t lend themselves to the conventional methods that researchers typically use to probe a material’s structure and chemistry.

One technique, called magic-angle spinning nuclear magnetic resonance, or MAS-NMR, has proven highly successful as a way of determining the properties of complex molecules such as some proteins. But the resolution achievable with such systems depends on the spinning frequency of tiny rotors, and these systems have bumped up against limits imposed by the rotor materials.

Most such devices used today rely on rotors made of yttria-stabilized zirconia, which are as thin as a pin. Such rotors fall apart if spun much faster than a few million revolutions per minute, limiting the materials that can be studied with such systems. But now, researchers at MIT have developed a method for making these tiny, precise rotors out of pure diamond crystal, whose much greater strength could allow it to spin at far higher frequencies. The advance opens the door to studying a wide variety of important molecules, including those found in the amyloid plaques associated with Alzheimer’s disease.

The new method is described in the Journal of Magnetic Resonance, in a paper by MIT graduate students Natalie Golota, Zachary Fredin, Daniel Banks, and David Preiss; professors Robert Griffin, Neil Gershenfeld, and Keith Nelson; and seven others at MIT.

The MAS-NMR technique, Gershenfeld says, “is the tool of choice for [analyzing] complex biological proteins in biologically meaningful environments.” For example, a sample could be analyzed in a liquid environment as opposed to being dried out or crystallized or coated for examination. “Only [solid-state] NMR does it in the ambient chemical environment,” he says.

The basic method has existed for decades, Griffin explains, and involves placing a tiny cylinder filled with the material to be studied into a magnetic field where it can be suspended and spun up to high frequencies using jets of gas, usually nitrogen, and then zapped with radio-frequency pulses to determine key properties of the material. The term “magic angle” refers to the fact that if the cylinder containing the sample spins at one precise angle (54.74 degrees) relative to the applied magnetic field, various sources of broadening of the spectral lines are attenuated and a much higher-resolution spectrum is possible.

<img alt=”Animated monochrome clip of inside of a spinning diamond as hole in center glows becomes increasingly round. Red lines resembling a shooting scope overlay the animation.” data-align=”center” data-caption=”This shows the process of making a hollow cylinder out of a block of diamond. The diamond spins while a laser beam burns off its outer layers and its interior.

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But the resolution of these spectra is directly limited by how fast the tiny cylinders, or rotors, can spin before they shatter. Over the years, early versions were made of various plastics, then later ceramic materials were used, and finally zirconium, “which is the material of choice that most rotors are made of these days,” Griffin says.

Such MAS-NMR systems are widely used in biochemical research as a tool for studying the molecular structure, down to the level of individual atoms, of materials including proteins that are difficult or impossible to probe using other standard lab methods. These include not only amyloid fibrils, but membrane proteins and some viral assemblies. But some of the most pressing challenges in both biomedical and materials science lie just beyond reach of the resolution of today’s MAS-NMR systems.

“As we progressed to spinning frequencies above 100 kilohertz,” equivalent to 6 million revolutions per minute, Griffin says, “these rotors have become very problematic. They fail about 50 percent of the time — and you lose a sample, and it destroys the NMR coil.” The team decided to tackle the problem, which many said at the time was impossible, of making the rotors out of single crystal diamond.

Even the company making the laser system they used thought it couldn’t be done, and it took years of work by an interdisciplinary team, involving students and researchers at both MIT’s Center for Bits and Atoms and the Department of Chemistry, to solve that fabrication problem. (The collaboration grew out of  Griffin and Gershenfeld serving on MIT’s Killian Award Committee). They developed a kind of laser-based lathe system that rapidly spins a piece of diamond while zapping it with the laser, essentially vaporizing its outer layers until a perfectly smooth cylinder remains, just 0.7 millimeters across (about 1/36 inch). Then, the same laser is used to drill a perfectly centered hole through the middle of the cylinder, leaving a sort of drinking-straw shape.

“It’s not obvious it would work,” Gershenfeld says, “but the laser turns the diamond into graphite and drives the carbon off, and you can incrementally do that to drill deep into the diamond.”

The diamond emerges from the machining process with a black coating of pure graphite, but the MIT researchers found that this could be eliminated by heating the rotor overnight at about 600 degrees Celsius (about 1,100 degrees Fahrenheit.) The result is a rotor that can already spin at 6 million revolutions per minute, the speed of the best zirconia rotors, and has other advantageous characteristics as well, including extremely high thermal conductivity and radio-frequency transparency.

Fredin points out that all the parts needed to make this high-precision machining system “were all designed and fabricated right here” in a basement lab in the Center for Bits and Atoms. “To be able to physically design and make everything and iterate it many times a day in-house was a crucial aspect of this project, as opposed to having to send things out to outside machine shops.”

Achieving much higher spinning frequencies should now be possible with these new rotors, the researchers say, but will require the development of new bearings and new systems based on helium rather than nitrogen to drive the rotation, in order to achieve the increased speeds and the corresponding leap in resolution. “It was never worth it to develop these helium-compatible bearings for these small rotors until this technology was proven out, when the rotors previously used would not be able to withstand the spinning speeds,” which could end up going as high as 20 million revolutions per minute, Golota says.

Such high rotation rates are almost unheard of outside the NMR field. Preiss says that as a mechanical engineer, “it’s rare that you’d encounter something spinning above tens of thousands of rpm.” When he first heard the 6 million rpm figure for these devices, he says, “I kind of thought it was a joke.”

Because of these high speeds, Gershenfeld says, instabilities can easily arise from any imperfection: “If there’s even a slight asymmetry in the structure, at these frequencies, you’re doomed.”

Golota says that in her experiments using current zirconia rotors, “when the rotors fail, they explode, and you essentially just recover dust. But when the diamond rotors fail, we were able to recover them intact. So, you’re saving the sample as well, which can be an invaluable resource to the user.”

They have already used the new diamond rotor to produce the carbon-13 and nitrogen-15 spectra of a small peptide, clearly demonstrating the capabilities of the new diamond rotor material, which Griffin says is the first new material for such rotors to be developed in the last three decades. “We’ve used spectra like these extensively,” he says, “to determine the structure of amyloid-beta 1-42, which is a toxic species in Alzheimer’s disease.” Samples of such material are hard to get and usually obtainable only in tiny quantities, he says. “We now have a small rotor that’s going to be hopefully very reliable where you can put in two or three milligrams of material and get spectral data like these,” he says, pointing to the sample data they obtained. “It’s really exciting and it’s going to open up a lot of new areas of research.”

This work “is truly remarkable,” says David Doty, president of Doty Scientific, a maker of NMR systems, who was not involved in this work. “It would have been very hard to find anyone outside this group who would have thought it possible to laser machine diamond rotors with the precision needed for fast-MAS, prior to actually seeing it work,” he says.

Doty adds, “What they have demonstrated thus far … is nothing short of amazing.  If the additional needed progress can be made, hundreds of NMR researchers will want these to help them get better data for the projects they are working on, from improving our understanding of some diseases and developing better drugs to developing advanced battery materials.”

“This new technology has the potential to be a game-changer in the way we will carry out solid-state NMR experiments in the future, opening unprecedented experimental opportunities in terms of resolution and sensitivity,” says Anne Lesage, adjunct director of the institute of analytical sciences at the Ecole Normale Superieure in Lyon, France, who also was not associated with this work.

The research team also included Salima Bahri, Daniel Banks, Prashant Patil, William Langford, Camron Blackburn, Erik Strand, Brian Michael, and Blake Dastrup, all at MIT. The work was supported by the U.S. National Institutes of Health, the CBA Consortia fund, the U.S. Department of Energy, and the U.S. National Science Foundation.

J-WAFS announces 2023 seed grant recipients

by Maria Paula Acosta Bello | Abdul Latif Jameel World Water and Food Systems Lab |

Today, the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) announced its ninth round of seed grants to support innovative research projects at MIT. The grants are designed to fund research efforts that tackle challenges related to water and food for human use, with the ultimate goal of creating meaningful impact as the world population continues to grow and the planet undergoes significant climate and environmental changes.

Ten new projects led by 15 researchers from seven different departments will be supported this year. The projects address a range of challenges by employing advanced materials, technology innovations, and new approaches to resource management. The new projects aim to remove harmful chemicals from water sources, develop monitoring and other systems to help manage various aquaculture industries, optimize water purification materials, and more.

“The seed grant program is J-WAFS’ flagship grant initiative,” says J-WAFS executive director Renee J. Robins. “The funding is intended to spur groundbreaking MIT research addressing complex issues that are challenging our water and food systems. The 10 projects selected this year show great promise, and we look forward to the progress and accomplishments these talented researchers will make,” she adds.

The 2023 J-WAFS seed grant researchers and their projects are:

Sara Beery, an assistant professor in the Department of Electrical Engineering and Computer Science (EECS), is building the first completely automated system to estimate the size of salmon populations in the Pacific Northwest (PNW).

Salmon are a keystone species in the PNW, feeding human populations for the last 7,500 years at least. However, overfishing, habitat loss, and climate change threaten extinction of salmon populations across the region. Accurate salmon counts during their seasonal migration to their natal river to spawn are essential for fisheries’ regulation and management but are limited by human capacity. Fish population monitoring is a widespread challenge in the United States and worldwide. Beery and her team are working to build a system that will provide a detailed picture of the state of salmon populations in unprecedented, spatial, and temporal resolution by combining sonar sensors and computer vision and machine learning (CVML) techniques. The sonar will capture individual fish as they swim upstream and CVML will train accurate algorithms to interpret the sonar video for detecting, tracking, and counting fish automatically while adapting to changing river conditions and fish densities.

Another aquaculture project is being led by Michael Triantafyllou, the Henry L. and Grace Doherty Professor in Ocean Science and Engineering in the Department of Mechanical Engineering, and Robert Vincent, the assistant director at MIT’s Sea Grant Program. They are working with Otto Cordero, an associate professor in the Department of Civil and Environmental Engineering, to control harmful bacteria blooms in aquaculture algae feed production.

Aquaculture in the United States represents a $1.5 billion industry annually and helps support 1.7 million jobs, yet many American hatcheries are not able to keep up with demand. One barrier to aquaculture production is the high degree of variability in survival rates, most likely caused by a poorly controlled microbiome that leads to bacterial infections and sub-optimal feed efficiency. Triantafyllou, Vincent, and Cordero plan to monitor the microbiome composition of a shellfish hatchery in order to identify possible causing agents of mortality, as well as beneficial microbes. They hope to pair microbe data with detail phenotypic information about the animal population to generate rapid diagnostic tests and explore the potential for microbiome therapies to protect larvae and prevent future outbreaks. The researchers plan to transfer their findings and technology to the local and regional aquaculture community to ensure healthy aquaculture production that will support the expansion of the U.S. aquaculture industry.

David Des Marais is the Cecil and Ida Green Career Development Professor in the Department of Civil and Environmental Engineering. His 2023 J-WAFS project seeks to understand plant growth responses to elevated carbon dioxide (CO2) in the atmosphere, in the hopes of identifying breeding strategies that maximize crop yield under future CO2 scenarios.

Today’s crop plants experience higher atmospheric CO2 than 20 or 30 years ago. Crops such as wheat, oat, barley, and rice typically increase their growth rate and biomass when grown at experimentally elevated atmospheric CO2. This is known as the so-called “CO2 fertilization effect.” However, not all plant species respond to rising atmospheric CO2 with increased growth, and for the ones that do, increased growth doesn’t necessarily correspond to increased crop yield. Using specially built plant growth chambers that can control the concentration of CO2, Des Marais will explore how CO2 availability impacts the development of tillers (branches) in the grass species Brachypodium. He will study how gene expression controls tiller development, and whether this is affected by the growing environment. The tillering response refers to how many branches a plant produces, which sets a limit on how much grain it can yield. Therefore, optimizing the tillering response to elevated CO2 could greatly increase yield. Des Marais will also look at the complete genome sequence of Brachypodium, wheat, oat, and barley to help identify genes relevant for branch growth.

Darcy McRose, an assistant professor in the Department of Civil and Environmental Engineering, is researching whether a combination of plant metabolites and soil bacteria can be used to make mineral-associated phosphorus more bioavailable.

The nutrient phosphorus is essential for agricultural plant growth, but when added as a fertilizer, phosphorus sticks to the surface of soil minerals, decreasing bioavailability, limiting plant growth, and accumulating residual phosphorus. Heavily fertilized agricultural soils often harbor large reservoirs of this type of mineral-associated “legacy” phosphorus. Redox transformations are one chemical process that can liberate mineral-associated phosphorus. However, this needs to be carefully controlled, as overly mobile phosphorus can lead to runoff and pollution of natural waters. Ideally, phosphorus would be made bioavailable when plants need it and immobile when they don’t. Many plants make small metabolites called coumarins that might be able to solubilize mineral-adsorbed phosphorus and be activated and inactivated under different conditions. McRose will use laboratory experiments to determine whether a combination of plant metabolites and soil bacteria can be used as a highly efficient and tunable system for phosphorus solubilization. She also aims to develop an imaging platform to investigate exchanges of phosphorus between plants and soil microbes.

Many of the 2023 seed grants will support innovative technologies to monitor, quantify, and remediate various kinds of pollutants found in water. Two of the new projects address the problem of per- and polyfluoroalkyl substances (PFAS), human-made chemicals that have recently emerged as a global health threat. Known as “forever chemicals,” PFAS are used in many manufacturing processes. These chemicals are known to cause significant health issues including cancer, and they have become pervasive in soil, dust, air, groundwater, and drinking water. Unfortunately, the physical and chemical properties of PFAS render them difficult to detect and remove.

Aristide Gumyusenge, the Merton C. Assistant Professor of Materials Science and Engineering, is using metal-organic frameworks for low-cost sensing and capture of PFAS. Most metal-organic frameworks (MOFs) are synthesized as particles, which complicates their high accuracy sensing performance due to defects such as intergranular boundaries. Thin, film-based electronic devices could enable the use of MOFs for many applications, especially chemical sensing. Gumyusenge’s project aims to design test kits based on two-dimensional conductive MOF films for detecting PFAS in drinking water. In early demonstrations, Gumyusenge and his team showed that these MOF films can sense PFAS at low concentrations. They will continue to iterate using a computation-guided approach to tune sensitivity and selectivity of the kits with the goal of deploying them in real-world scenarios.

Carlos Portela, the Brit (1961) and Alex (1949) d’Arbeloff Career Development Professor in the Department of Mechanical Engineering, and Ariel Furst, the Cook Career Development Professor in the Department of Chemical Engineering, are building novel architected materials to act as filters for the removal of PFAS from water. Portela and Furst will design and fabricate nanoscale materials that use activated carbon and porous polymers to create a physical adsorption system. They will engineer the materials to have tunable porosities and morphologies that can maximize interactions between contaminated water and functionalized surfaces, while providing a mechanically robust system.

Rohit Karnik is a Tata Professor and interim co-department head of the Department of Mechanical Engineering. He is working on another technology, his based on microbead sensors, to rapidly measure and monitor trace contaminants in water.

Water pollution from both biological and chemical contaminants contributes to an estimated 1.36 million deaths annually. Chemical contaminants include pesticides and herbicides, heavy metals like lead, and compounds used in manufacturing. These emerging contaminants can be found throughout the environment, including in water supplies. The Environmental Protection Agency (EPA) in the United States sets recommended water quality standards, but states are responsible for developing their own monitoring criteria and systems, which must be approved by the EPA every three years. However, the availability of data on regulated chemicals and on candidate pollutants is limited by current testing methods that are either insensitive or expensive and laboratory-based, requiring trained scientists and technicians. Karnik’s project proposes a simple, self-contained, portable system for monitoring trace and emerging pollutants in water, making it suitable for field studies. The concept is based on multiplexed microbead-based sensors that use thermal or gravitational actuation to generate a signal. His proposed sandwich assay, a testing format that is appealing for environmental sensing, will enable both single-use and continuous monitoring. The hope is that the bead-based assays will increase the ease and reach of detecting and quantifying trace contaminants in water for both personal and industrial scale applications.

Alexander Radosevich, a professor in the Department of Chemistry, and Timothy Swager, the John D. MacArthur Professor of Chemistry, are teaming up to create rapid, cost-effective, and reliable techniques for on-site arsenic detection in water.

Arsenic contamination of groundwater is a problem that affects as many as 500 million people worldwide. Arsenic poisoning can lead to a range of severe health problems from cancer to cardiovascular and neurological impacts. Both the EPA and the World Health Organization have established that 10 parts per billion is a practical threshold for arsenic in drinking water, but measuring arsenic in water at such low levels is challenging, especially in resource-limited environments where access to sensitive laboratory equipment may not be readily accessible. Radosevich and Swager plan to develop reaction-based chemical sensors that bind and extract electrons from aqueous arsenic. In this way, they will exploit the inherent reactivity of aqueous arsenic to selectively detect and quantify it. This work will establish the chemical basis for a new method of detecting trace arsenic in drinking water.

Rajeev Ram is a professor in the Department of Electrical Engineering and Computer Science. His J-WAFS research will advance a robust technology for monitoring nitrogen-containing pollutants, which threaten over 15,000 bodies of water in the United States alone.

Nitrogen in the form of nitrate, nitrite, ammonia, and urea can run off from agricultural fertilizer and lead to harmful algal blooms that jeopardize human health. Unfortunately, monitoring these contaminants in the environment is challenging, as sensors are difficult to maintain and expensive to deploy. Ram and his students will work to establish limits of detection for nitrate, nitrite, ammonia, and urea in environmental, industrial, and agricultural samples using swept-source Raman spectroscopy. Swept-source Raman spectroscopy is a method of detecting the presence of a chemical by using a tunable, single mode laser that illuminates a sample. This method does not require costly, high-power lasers or a spectrometer. Ram will then develop and demonstrate a portable system that is capable of achieving chemical specificity in complex, natural environments. Data generated by such a system should help regulate polluters and guide remediation.

Kripa Varanasi, a professor in the Department of Mechanical Engineering, and Angela Belcher, the James Mason Crafts Professor and head of the Department of Biological Engineering, will join forces to develop an affordable water disinfection technology that selectively identifies, adsorbs, and kills “superbugs” in domestic and industrial wastewater.

Recent research predicts that antibiotic-resistance bacteria (superbugs) will result in $100 trillion in health care expenses and 10 million deaths annually by 2050. The prevalence of superbugs in our water systems has increased due to corroded pipes, contamination, and climate change. Current drinking water disinfection technologies are designed to kill all types of bacteria before human consumption. However, for certain domestic and industrial applications there is a need to protect the good bacteria required for ecological processes that contribute to soil and plant health. Varanasi and Belcher will combine material, biological, process, and system engineering principles to design a sponge-based water disinfection technology that can identify and destroy harmful bacteria while leaving the good bacteria unharmed. By modifying the sponge surface with specialized nanomaterials, their approach will be able to kill superbugs faster and more efficiently. The sponge filters can be deployed under very low pressure, making them an affordable technology, especially in resource-constrained communities.

In addition to the 10 seed grant projects, J-WAFS will also fund a research initiative led by Greg Sixt. Sixt is the research manager for climate and food systems at J-WAFS, and the director of the J-WAFS-led Food and Climate Systems Transformation (FACT) Alliance. His project focuses on the Lake Victoria Basin (LVB) of East Africa. The second-largest freshwater lake in the world, Lake Victoria straddles three countries (Uganda, Tanzania, and Kenya) and has a catchment area that encompasses two more (Rwanda and Burundi). Sixt will collaborate with Michael Hauser of the University of Natural Resources and Life Sciences, Vienna, and Paul Kariuki, of the Lake Victoria Basin Commission.

The group will study how to adapt food systems to climate change in the Lake Victoria Basin. The basin is facing a range of climate threats that could significantly impact livelihoods and food systems in the expansive region. For example, extreme weather events like droughts and floods are negatively affecting agricultural production and freshwater resources. Across the LVB, current approaches to land and water management are unsustainable and threaten future food and water security. The Lake Victoria Basin Commission (LVBC), a specialized institution of the East African Community, wants to play a more vital role in coordinating transboundary land and water management to support transitions toward more resilient, sustainable, and equitable food systems. The primary goal of this research will be to support the LVBC’s transboundary land and water management efforts, specifically as they relate to sustainability and climate change adaptation in food systems. The research team will work with key stakeholders in Kenya, Uganda, and Tanzania to identify specific capacity needs to facilitate land and water management transitions. The two-year project will produce actionable recommendations to the LVBC.

Four researchers with MIT ties earn 2023 Schmidt Science Fellowships

by Danielle Doughty | Department of Chemistry |

Four researchers with ties to MIT have been named Schmidt Science Fellows this year. Lillian Chin ’17, SM ’19; Neil Dalvie PD ’22, PhD ’22; Suong Nguyen, and Yirui Zhang SM ’19, PhD ’23 are among the 32 exceptional early-career scientists worldwide chosen to receive the prestigious fellowships.

“History provides powerful examples of what happens when scientists are given the freedom to ask big questions which can achieve real breakthroughs across disciplines,” says Wendy Schmidt, co-founder of Schmidt Futures and president of the Schmidt Family Foundation. “Schmidt Science Fellows are tackling climate destruction, discovering new drugs against disease, developing novel materials, using machine learning to understand the drivers of human health, and much more. This new cohort will add to this legacy in applying scientific discovery to improve human health and opportunity, and preserve and restore essential planetary systems.”

Schmidt Futures is a philanthropic initiative that brings talented people together in networks to prove out their ideas and solve hard problems in science and society. Schmidt Science Fellows receive a stipend of $100,000 a year for up to two years of postdoctoral research in a discipline different from their PhD at a world-leading lab anywhere across the globe.

Lillian Chin ’17, SM ’19 is currently pursuing her PhD in the Department of Electrical Engineering and Computer Science. Her research focuses on creating new materials for robots. By designing the geometry of a material, Chin creates new “meta-materials” that have different properties from the original. Using this technique, she has created robot balls that dramatically expand in volume and soft grippers that can work in dangerous environments. All of these robots are built out of a single material, letting the researchers 3D print them with extra internal features like channels. These channels help to measure the deformation of metamaterials, enabling Chin and her collaborators to create robots that are strong, can move, and sense their own shape, like muscles do.

“I feel very honored to have been chosen for this fellowship,” says Chin. “I feel like I proposed a very risky pivot, since my background is only in engineering, with very limited exposure to neuroscience. I’m very excited to be given the opportunity to learn best practices for interacting with patients and be able to translate my knowledge from robotics to biology.”

With the Schmidt Fellowship, Chin plans to pursue new frontiers for custom materials with internal sensors, which can measure force and deformation and can be placed anywhere within the material. “I want to use these materials to make tools for clinicians and neuroscientists to better understand how humans touch and grasp objects around them,” says Chin. “I’m especially interested in seeing how my materials could help in diagnosis motor-related diseases or improve rehab outcomes by providing the patient with feedback. This will help me create robots that have a better sense of touch and learn how to move objects around like humans do.”

Neil Dalvie PD ’22, PhD ’22 is a graduate of the Department of Chemical Engineering, where he worked with Professor J. Christopher Love on manufacturing of therapeutic proteins. Dalvie developed molecular biology techniques for manufacturing high-quality proteins in yeast, which enables rapid testing of new products and low-cost manufacturing and large scales. During the pandemic, he led a team that applied these learnings to develop a Covid-19 vaccine that was deployed in multiple low-income countries. After graduating, Dalvie wanted to apply the precision biological engineering that is routinely deployed in medicinal manufacturing to other large-scale bioprocesses.

“It’s rare for scientists to cross large technical gaps after so many years of specific training to get a PhD — you get comfy being an expert in your field,” says Dalvie. “I was definitely intimidated by the giant leap from vaccine manufacturing to the natural rock cycle. The fellowship has allowed me to dive into the new field by removing immediate pressure to publish or find my next job. I am excited for what commonalities we will find between biomanufacturing and biogeochemistry.”

As a Schmidt Science Fellow, Dalvie will work with Professor Pamela Silver at Harvard Medical School on engineering microorganisms for enhanced rock weathering and carbon sequestration to combat climate change. They are applying modern molecular biology to enhance natural biogeochemical processes at gigaton scales.

Suong (Su) Nguyen, a postdoctoral researcher in Professor Jeremiah Johnson’s lab in the Department of Chemistry, earned her PhD from Princeton University, where she developed light-driven, catalytic methodologies for organic synthesis, biomass valorization, plastic waste recycling, and functionalization of quantum sensing materials.

As a Schmidt Science fellow, Nguyen will pivot from organic chemistry to nanomaterials. Biological systems are able to synthesize macromolecules with precise structure essential for their biological function. Scientists have long dreamed of achieving similar control over synthetic materials, but existing methods are inefficient and limited in scope. Nguyen hopes to develop new strategies to achieve such high level of control over the structure and properties of nanomaterials and explore their potential for use in therapeutic applications.

“I feel extremely honored and grateful to receive the Schmidt Science Fellowship,” says Nguyen. “The fellowship will provide me with a unique opportunity to engage with scientists from a very wide range of research backgrounds. I believe this will significantly shape the research objectives for my future career.”

Yirui Zhang SM ’19, PhD ’22 is a graduate of the Department of Mechanical Engineering. Zhang’s research focuses on electrochemical energy storage and conversion, including lithium-ion batteries and electrocatalysis. She has developed in situ spectroscopy and electrochemical methods to probe the electrode-electrolyte interface, understand the interfacial molecular structures, and unravel the fundamental thermodynamics and kinetics of (electro)chemical reactions in energy storage. Further, she has leveraged the physical chemistry of liquids and tuned the molecular structures at the interface to improve the stability and kinetics of electrochemical reactions.

“I am honored and thrilled to have been named a Schmidt Science Fellow,” says Zhang. “The fellowship will not only provide me with the unique opportunity to broaden my scientific perspectives and pursue pivoting research, but also create a lifelong network for us to collaborate across diverse fields and become scientific and societal thought leaders. I look forward to pushing the boundaries of my research and advancing technologies to tackle global challenges in energy storage and health care with interdisciplinary efforts!”

As a Schmidt Science Fellow, Zhang will work across disciplines and pivot to biosensing. She plans to combine spectroscopy, electrokinetics, and machine learning to develop a fast and cost-effective technique for monitoring and understanding infectious disease. The innovations will benefit next-generation point-of-care medical devices and wastewater-based epidemiology to provide timely diagnosis and help protect humans against deadly infections and antimicrobial resistance.

Study reveals new ways for exotic quasiparticles to “relax”

by David L. Chandler | MIT News Office |

New findings from a team of researchers at MIT and elsewhere could help pave the way for new kinds of devices that efficiently bridge the gap between matter and light. These might include computer chips that eliminate inefficiencies inherent in today’s versions, and qubits, the basic building blocks for quantum computers, that could operate at room temperature instead of the ultracold conditions needed by most such devices.

The new work, based on sandwiching tiny flakes of a material called perovskite in between two precisely spaced reflective surfaces, is detailed in the journal Nature Communications, in a paper by MIT recent graduate Madeleine Laitz PhD ’22, postdoc Dane deQuilettes, MIT professors Vladimir Bulovic, Moungi Bawendi and Keith Nelson, and seven others.

By creating these perovskite sandwiches and stimulating them with laser beams, the researchers were able to directly control the momentum of certain “quasiparticles” within the system. Known as exciton-polariton pairs, these quasiparticles are hybrids of light and matter. Being able to control this property could ultimately make it possible to read and write data to devices based on this phenomenon.

“What’s particularly fascinating about exciton-polaritons,” Laitz says, is that they lie “on a spectrum between purely electronic and photonic systems.” These quasiparticles “have the characteristics of both, and thus you can leverage exciton-polaritons to utilize the best properties of each.”

For example, purely electronic transistors, she explains, have inherent losses to capacitance effects at each interface between devices, whereas “purely photonic systems have challenges in engineering, in that it’s very hard to get photons to interact, and you have to rely on complex interferometric schemes.” By contrast, the quasiparticles used by this team can be easily controlled through multiple variables.

The quasiparticle is “a combined state of light and neutral charge,” Bulovic says. “As a result, you can perturb that combined state either with light or charge, and hence, if you need to modulate that state, you have extra levers you can utilize. These extra levers can now allow one to manipulate this combined state of matter in a more energy-efficient manner.”

What’s more, the materials involved are easily manufactured using room-temperature, solution-based processing methods, and thus could be relatively easy to produce at scale once practical systems are designed. So far, the work is at a very early stage, as researchers are still studying newly discovered effects; practical applications could be five to 10 years away, Laitz says.

Perovskites have attracted much attention in recent years as materials for new lightweight, flexible solar photovoltaic panels, so there has been a great deal of research on their properties and fabrication methods. The team settled on a particular version of perovskite called phenethylammonium lead iodide.

“Halide perovskites harvest light really well, and turn photons into electrons or excitons, depending on the dimensionality and material properties of the perovskite,” she says, which is why the researchers chose this particular version of this large class of materials for their research.

Then, to create what is known as an optical cavity that can trap photons of light, the researchers placed tiny flakes of the material between mirrored surfaces. Two of these ultrathin layers, just tens of nanometers thick, were spaced a precise distance apart using spacer layers, so that the mirrors were separated by half the wavelength of light that this perovskite material both absorbs and emits.

Using perovskite tuned to a wavelength of green light, the emitted green light then bounces back and forth between the mirrors. “It’s reabsorbed by the material, re-emitted, reabsorbed, re-emitted, reabsorbed over and over again so quickly that you’re interconverting between the photon and the exciton, such that you generate a superposition of both,” Laitz says.

This can lead to the state of matter known as a Bose-Einstein Condensate, in which all the particles have identical energy states and behave much like one large particle. Laitz says that such condensates carry a property known as spin, and this can be modified by light or electrical stimulation; the resulting changes can be measured by observing photoluminescence from the material using a spectroscopic imaging system. And unlike purely photonic systems, where there is little interaction between photons, these materials have strong interactions with both light and electrons.

Arrays of such condensates have been produced, but typically only at ultralow, cryogenic temperatures so far. “Perovskites offer the opportunity for realizing this phenomenon at elevated temperatures,” but it’s hard to form the condensates in perovskites. This new research shows fundamental characteristics of the process that leads to condensation, Laitz says. In their paper, “we propose several strategies from a material perspective and a device architecture perspective to enable this.” And that could be a key step toward eventual room-temperature qubits, she says.

While such devices may take several years to develop, a more near-term application of the new findings could be in producing new kinds of light-emitting devices, deQuilettes says, including ones that could provide a steerable light source with directional output that can be controlled electronically.

The research team also included Alexander Kaplan, Jude Deschamps, Ulugbek Barotov, Andrew Proppe, and Anna Asherov at MIT, Ines Garcia-Benito at Complutense University of Madrid, and Giulia Grancini at the University of Pavia. The work was supported by the Tata-MIT GridEdge Solar Research Program, the National Science Foundation, and the European Research Council.

Five MIT faculty elected to the National Academy of Sciences for 2023

by Mary Beth Gallagher | School of Engineering |

The National Academy of Sciences has elected 120 members and 23 international members, including five faculty members from MIT. Joshua Angrist, Gang Chen, Catherine Drennan, Dina Katabi, and Gregory Stephanopoulos were elected in recognition of their “distinguished and continuing achievements in original research.” Membership to the National Academy of Sciences is one of the highest honors a scientist can receive in their career.

Established in 1863 by a Congressional charter that was signed by Abraham Lincoln, the National Academy of Sciences is a private, nonprofit society of distinguished scholars. Each year, new members are elected by their peers in recognition of their outstanding contributions to their field of research. Together with the National Academy of Engineering and National Academy of Medicine, the National Academy of Sciences aims to “encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine.”

As of this year, the National Academy of Sciences has 2,565 active members and 526 international members. Among the new members added this year are eight MIT alumni, including Thomas Banks PhD ’73; Joan W. Bresnan PhD ’72; Jennifer Elisseeff PhD ’99; current faculty member Dina Katabi SM ’99, PhD ’03; Maria C. Lemos SM ’90, PhD ’95; William B. McKinnon ’76; Emmanuel Saez PhD ’99; and Gunther Uhlmann PhD ’76.

Joshua Angrist

Joshua Angrist is the Ford Professor of Economics at MIT, a co-founder and director of MIT’s Blueprint Labs, and a research associate at the National Bureau of Economic Research. Angrist and his collaborators have pioneered the use of natural experiments to answer important economic questions and developed new econometric tools that help social scientists and policymakers discover the causal effects of individual choices and government policy changes. Angrist’s research explores the economics of education and school reform, the impact of social programs on the labor market, and the labor market effects of immigration, regulation, and economic institutions.

Angrist received his bachelor’s degree in economics from Oberlin College in 1982 and completed his PhD in economics at Princeton University in 1989. He taught at Harvard University and the Hebrew University of Jerusalem before coming to MIT in 1996.

Angrist received the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel in 2021 with co-laureates Guido Imbens of the Stanford Graduate School of Business and David Card of the University of California at Berkeley. Angrist is a fellow of the American Academy of Arts and Sciences and the Econometric Society, a Margaret MacVicar Faculty Fellow, and has served as co-editor of the Journal of Labor Economics.

Gang Chen

Gang Chen is the Carl Richard Soderberg Professor of Power Engineering in the Department of Mechanical Engineering. Chen is a pioneer in nanoscale heat transfer and energy conversion. He has significantly contributed to the understanding of heat transfer and energy conversion mechanisms; developed high-performance thermoelectric materials, superior semiconductors, highly heat-conductive polymers, and water desalination materials; and advanced solar-thermal and solar photovoltaic technologies. Physics World chose Chen’s work on cubic boron arsenide being a superior semiconductor as a Top 10 Breakthrough in 2022. Scientific American highlighted his directional solvent extraction and thermally charged batteries technologies as one of its annual top 10 World Changing Ideas in 2012 and 2014. His work on high-performance thermoelectric materials won an R&D 100 award.

Chen earned both his bachelor’s and master’s degrees from Huazhong University of Science and Technology in China and his PhD from UC Berkeley. He worked at Duke University and UCLA before joining the MIT faculty in 2001. Chen served as department head of MIT’s Department of Mechanical Engineering from 2013 to 2018 and director of the Solid-State Solar-Thermal Energy Conversion Center for the U.S. Department of Energy EFRC from 2009 to 2018.

Chen is a dedicated mentor and advocate for diversity and inclusion in STEM fields. He has supervised 86 master’s and PhD theses and 60 postdocs. Chen received an NSF Young Investigator Award, an ASME Heat Transfer Memorial Award, an ASME Frank Kreith Award in Energy, a Nukiyama Memorial Award from Japan Heat Transfer Society, a World Technology Network Award in Energy, an SES Eringen Medal, and the Capers and Marion McDonald Award for Excellence in Mentoring and Advising from MIT. He is an academician of Academy Sinica, a fellow of the American Academy of Arts and Sciences, and a National Academy of Engineering member.

Catherine Drennan

Catherine Drennan, professor of biology and chemistry, combines X-ray crystallography, cryo-electron microscopy and other biophysical methods, with the goal of “visualizing” molecular processes by obtaining snapshots of enzymes in action.

Drennan earned her bachelor’s degree from Vassar College, and her PhD from the University of Michigan. Following a postdoctoral fellowship at Caltech, she joined the MIT faculty in 1999, and was named a Howard Hughes Medical Institute Professor in recognition of her teaching in 2006 and a Howard Hughes Medical Institute Investigator in recognition of her research in 2008. Drennan has led by example, dedicating herself to both research and teaching. Her educational initiatives include creating free resources for educators that help students recognize the underlying chemical principles in biology and medicine, and training graduate student teaching assistants and mentors to be effective teacher–scholars.

Recently, the American Society for Biochemistry and Molecular Biology chose Drennan as the recipient of the 2023 William C. Rose Award for her outstanding contributions to biochemical research and commitment to training younger scientists. Among her additional honors are the Everett Moore Baker Memorial Award for Excellence in Undergraduate Teaching, the Harold E. Edgerton Faculty Achievement Award, the Dean’s Educational and Student Advising Award, a Committed to Caring Award, and a Presidential Early Career Award for Scientists and Engineers (PECASE). She has also been named an MIT MacVicar Fellow, a AAAS fellow, an ASBMB fellow, an Alfred P Sloan Fellow, and a Searle Scholar, and she is a member of the American Academy of Arts and Sciences.

Dina Katabi

Dina Katabi is the Thuan and Nicole Pham Professor of Electrical Engineering and Computer Science (EECS), director of the MIT Center for Wireless Networks and Mobile Computing, and a principal investigator at both the Computer Science and Artificial Intelligence Laboratory (CSAIL) and the Abdul Latif Jameel Clinic for Machine Learning in Health (Jameel Clinic), and a co-founder of Emerald Innovations. At CSAIL, she conducts mobile computing, machine learning, and computer vision research while leading the NETMIT group. Katabi is known for her contributions to wireless data transmission, developing wireless devices that assist with digital health using AI and radio signals. These works include an in-home wireless device that continuously monitors the gait speed of patients with Parkinson’s to better track the progression of the disease, an AI model that detects Parkinson’s from individuals’ breathing patterns, and BodyCompass, a radio-frequency-based wireless device that captures sleep data without using cameras or body sensors.

Katabi received a bachelor’s of science from the University of Damascus and continued her studies at MIT, where she earned a master’s of science and a PhD in computer science. She joined EECS faculty in 2003.

She is a member of the American Academy of Arts and Sciences, the National Academy of Engineering, and the National Academy of Sciences, having received the 2013 MacArthur “genius grant” Fellowship as well as the Association for Computing Machinery Prize in Computing in 2018. Additionally, Katabi has earned the ACM Grace Murray Hopper Award, two Test of Time Awards from the ACM’s Special Interest Group on Data Communications, and a Sloan Research Fellowship.

Gregory Stephanopoulos

Gregory Stephanopoulos is the W. H. Dow Professor of Chemical Engineering and Biotechnology. His work focuses on biotechnology, specifically metabolic and biochemical engineering. His research group conducts research on various projects aiming at the development of biological production routes to chemical products and biofuels. The group is also investigating cancer as metabolic disease. He is renowned for his work in reprogramming the gene transcription network of particular bacteria in order to improve their efficiency in converting renewable raw material into valuable chemical products.

Stephanopoulos graduated from the National Technical University of Athens in 1973 with the a bachelor’s degree in chemical engineering. In 1975, he obtained his master’s degree from the University of Florida and, three years later, his PhD from the University of Minnesota. His professional career started in 1978 as assistant professor at Caltech, where he was promoted in 1984 to the rank of associate professor with tenure. In 1985, Stephanopoulos moved to MIT as a professor of chemical engineering. He was Bayer Professor between 2000 and 2006, when he was appointed to the W. H. Dow Professorship of Chemical Engineering and Biotechnology. From 1990 to 1997 he served as associate director of the Biotechnology Process Engineering Center (BPEC) at MIT. In 2016, he served as president of the American Institute of Chemical Engineers (AIChE).

Stephanopoulos has received many honors, including the 2019 Gaden Award for Biotechnology and Bioengineering, the 2017 Novozymes Award for Excellence in Biochemical and Chemical Engineering, and the 2016 Eric and Sheila Samson Prime Minister’s Prize for Innovation in Alternative Fuels. In 2010, he received the George Washington Carver Award for Innovation in Industrial Biotechnology and the ACS E. V. Murphree Award. From AIChE, he has received the R.H. Wilhelm Award (2001), the Founders Award (2007) and the William Walker Award (2014). In 2011, he received the Eni Prize in Renewable and Non-Conventional Energy, and in 2013 the John Fritz Medal from the American Association of Engineering Societies. Stephanopoulos is a member of the National Academy of Engineering and a corresponding member of the Academy of Athens.

Inaugural J-WAFS Grand Challenge aims to develop enhanced crop variants and move them from lab to land

by Carolyn Blais | Abdul Latif Jameel Water and Food Systems Lab |

According to MIT’s charter, established in 1861, part of the Institute’s mission is to advance the “development and practical application of science in connection with arts, agriculture, manufactures, and commerce.” Today, the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) is one of the driving forces behind water and food-related research on campus, much of which relates to agriculture. In 2022, J-WAFS established the Water and Food Grand Challenge Grant to inspire MIT researchers to work toward a water-secure and food-secure future for our changing planet. Not unlike MIT’s Climate Grand Challenges, the J-WAFS Grand Challenge seeks to leverage multiple areas of expertise, programs, and Institute resources. The initial call for statements of interests returned 23 letters from MIT researchers spanning 18 departments, labs, and centers. J-WAFS hosted workshops for the proposers to present and discuss their initial ideas. These were winnowed down to a smaller set of invited concept papers, followed by the final proposal stage.

Today, J-WAFS is delighted to report that the inaugural J-WAFS Grand Challenge Grant has been awarded to a team of researchers led by Professor Matt Shoulders and research scientist Robert Wilson of the Department of Chemistry. A panel of expert, external reviewers highly endorsed their proposal, which tackles a longstanding problem in crop biology — how to make photosynthesis more efficient. The team will receive $1.5 million over three years to facilitate a multistage research project that combines cutting-edge innovations in synthetic and computational biology. If successful, this project could create major benefits for agriculture and food systems worldwide.

“Food systems are a major source of global greenhouse gas emissions, and they are also increasingly vulnerable to the impacts of climate change. That’s why when we talk about climate change, we have to talk about food systems, and vice versa,” says Maria T. Zuber, MIT’s vice president for research. “J-WAFS is central to MIT’s efforts to address the interlocking challenges of climate, water, and food. This new grant program aims to catalyze innovative projects that will have real and meaningful impacts on water and food. I congratulate Professor Shoulders and the rest of the research team on being the inaugural recipients of this grant.”

Shoulders will work with Bryan Bryson, associate professor of biological engineering, as well as Bin Zhang, associate professor of chemistry, and Mary Gehring, a professor in the Department of Biology and the Whitehead Institute for Biomedical Research. Robert Wilson from the Shoulders lab will be coordinating the research effort. The team at MIT will work with outside collaborators Spencer Whitney, a professor from the Australian National University, and Ahmed Badran, an assistant professor at the Scripps Research Institute. A milestone-based collaboration will also take place with Stephen Long, a professor from the University of Illinois at Urbana-Champaign. The group consists of experts in continuous directed evolution, machine learning, molecular dynamics simulations, translational plant biochemistry, and field trials.

“This project seeks to fundamentally improve the RuBisCO enzyme that plants use to convert carbon dioxide into the energy-rich molecules that constitute our food,” says J-WAFS Director John H. Lienhard V. “This difficult problem is a true grand challenge, calling for extensive resources. With J-WAFS’ support, this long-sought goal may finally be achieved through MIT’s leading-edge research,” he adds.

RuBisCO: No, it’s not a new breakfast cereal; it just might be the key to an agricultural revolution

A growing global population, the effects of climate change, and social and political conflicts like the war in Ukraine are all threatening food supplies, particularly grain crops. Current projections estimate that crop production must increase by at least 50 percent over the next 30 years to meet food demands. One key barrier to increased crop yields is a photosynthetic enzyme called Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase (RuBisCO). During photosynthesis, crops use energy gathered from light to draw carbon dioxide (CO2) from the atmosphere and transform it into sugars and cellulose for growth, a process known as carbon fixation. RuBisCO is essential for capturing the CO2 from the air to initiate conversion of CO2 into energy-rich molecules like glucose. This reaction occurs during the second stage of photosynthesis, also known as the Calvin cycle. Without RuBisCO, the chemical reactions that account for virtually all carbon acquisition in life could not occur.

Unfortunately, RuBisCO has biochemical shortcomings. Notably, the enzyme acts slowly. Many other enzymes can process a thousand molecules per second, but RuBisCO in chloroplasts fixes less than six carbon dioxide molecules per second, often limiting the rate of plant photosynthesis. Another problem is that oxygen (O2) molecules and carbon dioxide molecules are relatively similar in shape and chemical properties, and RuBisCO is unable to fully discriminate between the two. The inadvertent fixation of oxygen by RuBisCO leads to energy and carbon loss. What’s more, at higher temperatures RuBisCO reacts even more frequently with oxygen, which will contribute to decreased photosynthetic efficiency in many staple crops as our climate warms.

The scientific consensus is that genetic engineering and synthetic biology approaches could revolutionize photosynthesis and offer protection against crop losses. To date, crop RuBisCO engineering has been impaired by technological obstacles that have limited any success in significantly enhancing crop production. Excitingly, genetic engineering and synthetic biology tools are now at a point where they can be applied and tested with the aim of creating crops with new or improved biological pathways for producing more food for the growing population.

An epic plan for fighting food insecurity

The 2023 J-WAFS Grand Challenge project will use state-of-the-art, transformative protein engineering techniques drawn from biomedicine to improve the biochemistry of photosynthesis, specifically focusing on RuBisCO. Shoulders and his team are planning to build what they call the Enhanced Photosynthesis in Crops (EPiC) platform. The project will evolve and design better crop RuBisCO in the laboratory, followed by validation of the improved enzymes in plants, ultimately resulting in the deployment of enhanced RuBisCO in field trials to evaluate the impact on crop yield.

Several recent developments make high-throughput engineering of crop RuBisCO possible. RuBisCO requires a complex chaperone network for proper assembly and function in plants. Chaperones are like helpers that guide proteins during their maturation process, shielding them from aggregation while coordinating their correct assembly. Wilson and his collaborators previously unlocked the ability to recombinantly produce plant RuBisCO outside of plant chloroplasts by reconstructing this chaperone network in Escherichia coli (E. coli). Whitney has now established that the RuBisCO enzymes from a range of agriculturally relevant crops, including potato, carrot, strawberry, and tobacco, can also be expressed using this technology. Whitney and Wilson have further developed a range of RuBisCO-dependent E. coli screens that can identify improved RuBisCO from complex gene libraries. Moreover, Shoulders and his lab have developed sophisticated in vivo mutagenesis technologies that enable efficient continuous directed evolution campaigns. Continuous directed evolution refers to a protein engineering process that can accelerate the steps of natural evolution simultaneously in an uninterrupted cycle in the lab, allowing for rapid testing of protein sequences. While Shoulders and Badran both have prior experience with cutting-edge directed evolution platforms, this will be the first time directed evolution is applied to RuBisCO from plants.

Artificial intelligence is changing the way enzyme engineering is undertaken by researchers. Principal investigators Zhang and Bryson will leverage modern computational methods to simulate the dynamics of RuBisCO structure and explore its evolutionary landscape. Specifically, Zhang will use molecular dynamics simulations to simulate and monitor the conformational dynamics of the atoms in a protein and its programmed environment over time. This approach will help the team evaluate the effect of mutations and new chemical functionalities on the properties of RuBisCO. Bryson will employ artificial intelligence and machine learning to search the RuBisCO activity landscape for optimal sequences. The computational and biological arms of the EPiC platform will work together to both validate and inform each other’s approaches to accelerate the overall engineering effort.

Shoulders and the group will deploy their designed enzymes in tobacco plants to evaluate their effects on growth and yield relative to natural RuBisCO. Gehring, a plant biologist, will assist with screening improved RuBisCO variants using the tobacco variety Nicotiana benthamianaI, where transient expression can be deployed. Transient expression is a speedy approach to test whether novel engineered RuBisCO variants can be correctly synthesized in leaf chloroplasts. Variants that pass this quality-control checkpoint at MIT will be passed to the Whitney Lab at the Australian National University for stable transformation into Nicotiana tabacum (tobacco), enabling robust measurements of photosynthetic improvement. In a final step, Professor Long at the University of Illinois at Urbana-Champaign will perform field trials of the most promising variants.

Even small improvements could have a big impact

A common criticism of efforts to improve RuBisCO is that natural evolution has not already identified a better enzyme, possibly implying that none will be found. Traditional views have speculated a catalytic trade-off between RuBisCO’s specificity factor for CO2 / O2 versus its CO2 fixation efficiency, leading to the belief that specificity factor improvements might be offset by even slower carbon fixation or vice versa. This trade-off has been suggested to explain why natural evolution has been slow to achieve a better RuBisCO. But Shoulders and the team are convinced that the EPiC platform can unlock significant overall improvements to plant RuBisCO. This view is supported by the fact that Wilson and Whitney have previously used directed evolution to improve CO2 fixation efficiency by 50 percent in RuBisCO from cyanobacteria (the ancient progenitors of plant chloroplasts) while simultaneously increasing the specificity factor.

The EPiC researchers anticipate that their initial variants could yield 20 percent increases in RuBisCO’s specificity factor without impairing other aspects of catalysis. More sophisticated variants could lift RuBisCO out of its evolutionary trap and display attributes not currently observed in nature. “If we achieve anywhere close to such an improvement and it translates to crops, the results could help transform agriculture,” Shoulders says. “If our accomplishments are more modest, it will still recruit massive new investments to this essential field.”

Successful engineering of RuBisCO would be a scientific feat of its own and ignite renewed enthusiasm for improving plant CO2 fixation. Combined with other advances in photosynthetic engineering, such as improved light usage, a new green revolution in agriculture could be achieved. Long-term impacts of the technology’s success will be measured in improvements to crop yield and grain availability, as well as resilience against yield losses under higher field temperatures. Moreover, improved land productivity together with policy initiatives would assist in reducing the environmental footprint of agriculture. With more “crop per drop,” reductions in water consumption from agriculture would be a major boost to sustainable farming practices.

“Our collaborative team of biochemists and synthetic biologists, computational biologists, and chemists is deeply integrated with plant biologists and field trial experts, yielding a robust feedback loop for enzyme engineering,” Shoulders adds. “Together, this team will be able to make a concerted effort using the most modern, state-of-the-art techniques to engineer crop RuBisCO with an eye to helping make meaningful gains in securing a stable crop supply, hopefully with accompanying improvements in both food and water security.”

Chemists’ technique reveals whether antibodies neutralize SARS-CoV-2

by Anne Trafton | MIT News Office |

Antibodies that can disarm a virus, known as neutralizing antibodies, are key to the body’s ability to fight off infection. MIT chemists have come up with a new way to identify these neutralizing antibodies in a blood sample, by analyzing how antibodies interact with sugar molecules found on the surface of a viral protein.

The new test could help to reveal whether someone has neutralizing antibodies against viruses such as SARS-CoV-2, the virus that the researchers focused on in their study. Neutralizing antibodies, which can be generated by vaccination or a previous infection, offer protection against future infections.

“This type of assay could be used to check whether patients are really protected by vaccines or not,” says Laura Kiessling, the Novartis Professor of Chemistry at MIT and the senior author of the paper. “If someone is at high risk, it would be really good to be able to rapidly determine if they have neutralizing antibodies.”

This technique, which uses general equipment already found in many biochemistry labs, could also help researchers to determine how well current vaccines might protect against emerging variants of SARS-CoV-2, Kiessling says.

Former MIT postdoc Michael Wuo and MIT research scientist Amanda Dugan are the lead authors of the paper, which appears today in the open-access journal ACS Central Science.

Neutralizing or not?

Most vaccines for SARS-CoV-2 target the spike protein of the virus, which the virus uses to enter host cells through the ACE2 receptor. Like most proteins found on viral envelopes, the spike protein is heavily coated in sugar chains that hang from the protein.

Kiessling, whose lab studies how proteins interact with carbohydrates found on cell surfaces, wondered if it might be possible to create a “fingerprint” of different antibodies, based on how they interact with the sugar molecules found on a viral protein such as the SARS-CoV-2 spike protein.

“To tell whether an antibody is neutralizing or not, you usually have to do a relatively difficult set of assays,” Kiessling says. “You have to test whether or not the antibody blocks the virus from infecting cells. We thought if we could develop this fingerprint, then we could identify neutralizing antibodies much more rapidly.”

To do that, the researchers created a panel of commercially available lectins (proteins that bind to carbohydrates), taken from a variety of organisms, mostly plants and bacteria. Lectins, which are normally involved in functions such as cell-cell interactions and immune responses, bind to the sugar molecule at the very end of a sugar chain as it dangles from a protein.

When the researchers expose the SARS-CoV-2 spike protein to these lectins, each lectin attaches to a particular subset of sugar molecules found on the protein. Then, the researchers add serum containing antibodies against SARS-CoV-2. If the antibodies have a high affinity for the spike protein, they jostle the lectins already there out of the way.

Each antibody displaces a different set of lectins, depending on its binding specificity, and this displacement can be measured using a laboratory test known as enzyme-linked lectin assay (ELLA). By analyzing whether each antibody displaced 28 different lectins bound to the spike protein, the researchers were able to identify patterns of lectin displacement, creating a distinctive “fingerprint” for each antibody.

The researchers first identified fingerprints for antibodies that were already known to be either neutralizing or non-neutralizing. Then, they tested patient blood samples and were able to determine whether antibodies from those samples were neutralizing or not, by comparing them to the fingerprints produced by the known neutralizing antibodies.

“By looking at the different patterns, we could see that neutralizing antibodies fell into a different category as the non-neutralizing antibodies,” Kiessling says.

Antibody profiles

Using this analysis, the researchers were also able to categorize antibodies based on whether they came from people who received the Moderna Covid-19 vaccine or the Pfizer Covid-19 vaccine, each of which targets slightly different viral RNA sequences.

The researchers have filed for a patent on the technology, which they hope could be developed to perform rapid tests in a doctor’s office to determine the antibody profile of individual patients.

This technique could potentially be adapted to identify neutralizing antibodies against new variants of SARS-CoV-2, or other disease-causing viruses, Kiessling says. Now that the researchers have a panel of lectins that can be used for the test, they would simply need to re-run the analysis with antibodies that are known to be neutralizing and non-neutralizing, so they can determine the correct fingerprint for those antibodies.

“We could use the same panel of lectins for all SARS-CoV-2 variants of concern,” Kiessling says. “It can be useful for any new viruses that emerge, as long as they have a viral envelope.”

Other authors of the paper include Melanie Halim, Blake Hauser, Jared Feldman, Timothy Caradonna, Shuting Zhang, Lauren Pepi, Caroline Atyeo, Stephanie Fischinger, Galit Alter, Wilfredo Garcia-Beltran, Parastoo Azadi, Deb Hung, and Aaron Schmidt.

The research was funded by the National Cancer Institute, the National Institute for Allergy and Infectious Disease, the MIT Center for Microbiome Informatics, the Massachusetts Consortium on Pathogenesis Readiness, the National Institute for General Medical Science, and GlycoMIP, a National Science Foundation Materials Innovation Platform.

MIT graduate engineering, business, science programs ranked highly by U.S. News for 2023-24

by MIT News Office |

U.S. News and Word Report has again placed MIT’s graduate program in engineering at the top of its annual rankings. The Institute has held the No. 1 spot since 1990, when the magazine first ranked such programs.

The MIT Sloan School of Management also placed highly. It occupies the No. 4 spot for the best graduate business programs, tied with Harvard University.

Among individual engineering disciplines, MIT placed first in six areas: aerospace/aeronautical/astronautical engineering, chemical engineering, computer engineering, electrical/electronic/communications engineering, materials engineering, and mechanical engineering. It placed second in nuclear engineering.

In the rankings of individual MBA specialties, MIT placed first in three areas: business analytics, production/operations, and project management. It placed second in information systems and supply chain/logistics.

U.S. News does not issue annual rankings for all doctoral programs but revisits many every few years. This year, the magazine ranked the nation’s top PhD programs in several science fields. MIT’s chemistry program earned a No. 1 ranking, shared with Caltech and the University of California at Berkeley. Its computer science program also earned a No. 1 ranking, shared with Stanford University and UC Berkeley. MIT’s mathematics program shared the top spot with Princeton University, and its physics program placed first along with Stanford. MIT ranked second among Earth science programs.

The magazine bases its rankings of graduate schools of engineering and business on two types of data: reputational surveys of deans and other academic officials, and statistical indicators that measure the quality of a school’s faculty, research, and students. The magazine’s less-frequent rankings of programs in the sciences, social sciences, and humanities are based solely on reputational surveys.