A research team, led by Professor Dong Woog Lee from the Department of Chemistry at UNIST, in collaboration with Professor Byeong-Su Kim from the Department of Chemistry at Yonsei University, has discovered that the synergistic anion–π interactions serve as a key principle in enhancing the cohesion of synthetic polymers.
In this study, the researchers developed an epoxy monomer-based polymer that mimics the structural features of mussel foot proteins and experimentally demonstrated that anion–π interactions are pivotal in strengthening polymer cohesion.
The paper is published in the journal Proceedings of the National Academy of Sciences.
Anion–π interactions are non-covalent bonds formed between negatively charged molecules (anions) and the π electron systems of aromatic rings. While these interactions are known to play critical roles in biological processes such as enzyme catalysis and ion transport, research exploring their application in synthetic polymers remains scarce.
Inspired by mussels, which exhibit remarkable adhesive properties in natural environments, the research team focused on the plantar proteins of these organisms. Through an analysis of the key components contributing to their strong binding capabilities, the scientists found that the structural characteristics of 3,4-dihydroxyphenylalanine (DOPA) and aspartic acid are particularly significant.
To advance their findings, the research team designed functional monomers that replicate these structural features, leading to the synthesis of a novel polymer. This work proposes a new design methodology for polymers, taking into account the complex intermolecular interactions present in biological systems.
Specifically, the monomer that emulates the DOPA structure provides the π-electronic field of the aromatic ring, while the monomer representing aspartic acid introduces the anion necessary for anion–π interactions within the polymer framework. Furthermore, the team employed a surface force apparatus (SFA) to quantitatively analyze the cohesiveness of the polymer under various conditions.
The team compared the cohesion of the polymer in neutral environments, where its functional groups are ionized, against acidic conditions, where they remain non-ionized.
Their findings revealed that in neutral environments, anion–π interactions serve as the principal binding force, significantly enhancing polymer cohesion. In contrast, under acidic conditions, hydrogen bonding dominates, resulting in comparatively weaker cohesion.
This study marks the first experimental evidence highlighting the decisive role of anion–π interactions in reinforcing cohesion among synthetic polymers.
The implications of these findings open avenues for innovative polymer design strategies applicable in diverse fields, including adhesives, self-assembly systems, catalysts, and drug delivery.
More information: Seunghyun Lee et al, Synergistic anion–π interactions in peptidomimetic polyethers, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2419404122
A small team of materials scientists and chemical engineers at Qingdao University, in China, has developed a self-powered, three-component biosensor that can kill bacteria in water samples. The study is published in the journal Advanced Functional Materials.
As the world’s population continues to rise, scientists are looking for ways to sustain so many people. One area of concern is safe drinking water, particularly in regions that do not have sophisticated water treatment facilities. In this new effort, the team in China developed a biosensor that could, in theory, be used in developing countries to make water safe for drinking.
Biosensors are made using living organisms or tissues. Prior research has shown that they can be faster and less expensive than those based on traditional technology, especially in applications such as testing water for the presence of bacteria. Unfortunately, they tend to also suffer from degradation.
The researchers overcame this problem by creating their biosensor with three components. The first was an enzyme-based fuel cell to power the cell. The enzymes generate electricity via chemical reactions that occur once the sensor is placed in a water sample. To prevent their power generator from losing stability, the team put it in a hollow metal-organic framework.
The second component used a type of antibody known as an aptamer—their DNA strands were chosen specifically to bind with the exterior of an E. coli bacterium.
The third component was the part that kills the bacteria. It is accomplished by the oxidation of the silver nanoparticles used by the second component. The oxidation produces hydrogen peroxide, which kills the bacterium.
In testing, the sensor was capable of detecting E. coli at very low concentrations. It was also efficient, killing 99.9% of bacteria in a given sample over just a few hours. The biosensor also distinguished between different kinds of bacteria, suggesting it could be modified to kill other microbes as well. When tested on seawater samples, the sensor had recovery rates of 91.06% to 101.9% and remained workable after five user cycles.
More information: Yanfang Wang et al, Self‐Powered Biosensor‐Based Multifunctional Platform for Detection and In Situ Elimination of Bacteria, Advanced Functional Materials (2025). DOI: 10.1002/adfm.202420480
Boron, carbon, nitrogen and oxygen: these four elements can form chemical triple bonds with each other due to their similar electronic properties. Examples of this are the gas carbon monoxide, which consists of one carbon and one oxygen atom, or the nitrogen gas in the Earth’s atmosphere with its two nitrogen atoms.
Chemistry recognizes triple bonds between all possible combinations of the four elements—but not between boron and carbon. This is astonishing because there have long been stable double bonds between boron and carbon. In addition, many molecules are known in which triple bonds exist between two carbon atoms or between two boron atoms.
Chemists at Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany, have now closed this gap: A team led by boron expert Professor Holger Braunschweig has succeeded for the first time in synthesizing a molecule with a boron-carbon triple bond, a so-called boryne, which exists as an orange solid at room temperature.
The scientists characterized the new molecule and also carried out initial reactivity studies. They present the results in the journal Nature Synthesis.
Boron atom in an uncomfortable situation
In the novel molecule, the boron atom is in a linear arrangement with carbon atoms. “In combination with the triple bond, this is about as uncomfortable as it gets for boron, requiring very special conditions,” says Dr. Rian Dewhurst, co-author of the study. This is why it has taken so long to synthesize such a triple bond for the first time.
What interests the Würzburg chemists about the new molecule: “Compounds in which individual atoms feel ‘uncomfortable’ often show a very interesting reactivity,” explains Maximilian Michel, the doctoral student who made the molecule in the laboratory.
It is precisely this reactivity that the team’s further work is now focusing on. Ultimately, this may result in innovative tools for chemical syntheses. The findings could also be helpful for a better understanding of chemical bonds and structures.
“Another benefit that is often overlooked: Basic research like ours inspires other researchers to put their efforts and imagination into synthesizing compounds that might seem improbable,” says Dewhurst. “World-changing advances often emerge from these kinds of crazy ideas.”
Teflon, for example, was discovered during research originally aimed at developing new refrigerants, while the well-known product superglue emerged by chance during attempts to produce transparent plastics.
Some beetles, such as Anomala albopilosa, strongly reflect left circularly polarized light (electromagnetic waves that oscillate leftward relative to the direction of light reception). This property originates from the formation of a cholesteric liquid crystal phase with an optically active, helical structure during chrysalis during exoskeleton formation and the solidification of this phase into a rigid skeleton while retaining its helical structure.
Researchers at the University of Tsukuba have coated the surface of its exoskeleton with an electrically conductive polymer, polyaniline. The polymer does not reflect circularly polarized light; however, electrical or chemical oxidation of the polymer changes its coloration, thereby changing its light transmittance.
By combining the color change caused by the oxidation and reduction of polyaniline with the exoskeleton’s properties of reflecting circularly polarized light, the researchers have crafted a new polymer element that can modulate the reflection intensity of the circularly polarized light. The work is published in the journal Next Materials.
First, the researchers examined the circularly polarized light reflectance of the exoskeleton. They confirmed that the green reflection of the exoskeleton is not caused by dyes, etc., but is a structural color (i.e., its coloration results from the reflection of light from the surface microstructure). They also confirmed that the exoskeleton strongly reflects left circularly polarized light.
Next, they coated the exoskeleton with polyaniline and created a polymer element with a two-layered structure comprising a conductive polymer and a sheath spring. For this coating, they measured the circularly polarized reflectance spectra of polyaniline in the oxidized state by doping it with ammonia and in the reduced state by dedoping.
They found that no circularly polarized light was reflected in the oxidized state. However, in the reduced state, left circularly polarized light was reflected. This research realizes a new bio/synthetic photofunctional material that combines the excellent optical properties of insects and the external field responsiveness of conductive polymers.
More information: Hiromasa Goto et al, Circularly polarized reflection spectra of a photonic beetle and preparation of tunable circularly polarized light reflecting device consisting of conductive polymer/beetle exoskeleton, Next Materials (2025). DOI: 10.1016/j.nxmate.2025.100516
Researchers in South Korea have developed a cobalt-iron (CoFe)-based non-noble metal ammonia decomposition catalyst, advancing eco-friendly hydrogen production. The work is published in the Chemical Engineering Journal.
The research team led by Dr. Su-Un Lee and Dr. Ho-Jeong Chae from the Korea Research Institute of Chemical Technology (KRICT) has successfully developed a high-performance ammonia decomposition catalyst by incorporating cerium oxide (CeO2) into a cobalt-iron-based layered double oxide (LDO) structure. This innovation enables high ammonia decomposition efficiency at lower temperatures.
Ammonia (NH3) is gaining attention as a carbon-free hydrogen carrier due to its high hydrogen storage capacity and transport efficiency.
However, extracting hydrogen from ammonia requires a high-temperature decomposition process, typically facilitated by catalysts. Ruthenium (Ru) catalysts demonstrate the highest efficiency in this reaction, but their high cost and the need for elevated temperatures pose significant barriers to large-scale application.
To overcome these challenges, the research team developed a CoFe-based non-noble metal catalyst enhanced with cerium oxide (CeO2). This catalyst offers high ammonia decomposition efficiency at lower temperatures, ensuring cost efficiency and long-term stability.
Comparison of ammonia decomposition performance between the developed catalyst and existing catalysts. Credit: Korea Research Institute of Chemical Technology (KRICT)
Advantages of cerium oxide incorporation:
Prevents particle agglomeration: Adjusts the surface structure of CoFe-based LDO catalysts, preventing metal nanoparticle sintering.
Enhances catalytic properties: Utilizes Ce3+/Ce4+ redox transitions to modulate the electronic characteristics of the catalyst.
Facilitating the rate-determining step:
The rate-determining step in ammonia decomposition is nitrogen recombination-desorption from the catalyst surface.
The newly developed catalyst optimizes this process, significantly accelerating ammonia decomposition even at lower temperatures.
Thanks to these advancements, the catalyst achieved 81.9% ammonia conversion at 450°C, surpassing previous non-noble metal catalysts.
This marks a significant improvement compared to a 2022 nickel-based catalyst, which exhibited only 45% conversion at 450°C.
Furthermore, long-term stability tests at 550°C demonstrated that the catalyst maintained structural integrity and hydrogen production efficiency even after prolonged operation.
The research team aims to further enhance low-temperature hydrogen production efficiency through additional studies, targeting commercialization by 2030.
“This catalyst can be applied to large-scale ammonia-based hydrogen production, hydrogen power plants, hydrogen fueling stations, and maritime industries,” Dr. Su-Un Lee stated.
More information: Su-Un Lee et al, CeO2-conjugated CoFe layered double oxides as efficient non-noble metal catalysts for NH3-decomposition enabling carbon-free hydrogen production, Chemical Engineering Journal (2024). DOI: 10.1016/j.cej.2024.156986
How can we produce clean hydrogen without burning fossil hydrocarbons or other non-renewable energy sources? We can do so through photoelectrochemistry, or artificial photosynthesis, a method that—just like photosynthesis—uses sunlight and water, as with electrolysis, to obtain hydrogen, without generating harmful emissions. A group of researchers from the Department of Physics of the University of Trento has focused precisely on this approach.
One of the most innovative aspects of their research project is the use of photocatalysts (semiconductor materials) based on two-dimensional materials, and in particular, on graphitic carbon nitride (g-C3N4). This material is lightweight and sustainable and is used to break the chemical bond of the water molecules to produce hydrogen.
The research has shown that when used in the form of a single atomic layer, these photocatalysts offer superior performance compared to the thicker and less orderly structures previously tested. This discovery could open the way to a more efficient use of these materials in the production of green hydrogen.
Hydrogen is considered one of the most promising solutions for energy transition. But most hydrogen produced today is made via the “steam reforming” method, where methane (a fossil fuel) is heated to high temperatures; a process that is not fully sustainable. The Trento-based research team instead focuses on the production of hydrogen through photoelectrochemical cells.
This is a clean process that does not use hydrocarbons or other non-renewable energy sources to break the chemical bond of the water molecules to produce hydrogen.
“The graphitic compound based on graphitic carbon nitride has been suggested as a possible photocatalyst. In contact with water, this semiconductor absorbs visible sunlight and transforms it into chemical energy to allow the movement of electrons within matter. Before our work, little was known about these mechanisms,” explains Francesca Martini, lead author of the study.
“By studying the formation and propagation of excitons (a bound electron-hole pair), particles produced by sunlight in carbon nitride formed by a single layer of atoms, we realized that they have a very low speed and move in the photocatalyst thanks to a combined motion that includes the vibrations of the atoms.”
The authors of the study are surprised by this result. The electrons are more than two thousand times smaller than the atoms of the photocatalyst. Therefore, they move faster, just as a swarm of insects (the electrons) moves around a person (the atom). This, however, does not happen in carbon nitride. It is as if the swarm of insects agrees with the person to walk arm in arm like a couple, until they meet a hydrogen ion together.
“When this happens,” explains Matteo Calandra, study coordinator, “the atom bows and lets the electron that binds to the hydrogen ion pass through. Just as the father (the atom) of the bride (the electron) does when he takes her to the altar (hydrogen ion).”
The work of researchers will continue as they will perform numerical simulations on a database of over five thousand materials to which they have access, to perform a computational screening and identify better catalysts than the current ones.
“We hope that this research will lead to a strong innovation in the production of hydrogen from photoelectrolytic cells. Thanks to this methodology, we can now systematically identify better-performing materials and accelerate progress in the production of green hydrogen,” concludes Pietro Brangi, co-author of the study.
This project represents a significant step towards energy sustainability.
More information: Francesca Martini et al, Ultraflat excitonic dispersion in single layer g-C3N4, Carbon (2024). DOI: 10.1016/j.carbon.2024.119951
The world’s demand for alternative fuels and sustainable chemical products has prompted many scientists to look in the same direction for answers: converting carbon dioxide (CO2) into carbon monoxide (CO).
But the labs of Yale chemists Nilay Hazari and James Mayer have a different chemical destination in mind. In a new study, Hazari, Mayer, and their collaborators present a new method for transforming CO2 into a chemical compound known as formate—which is used primarily in preservatives and pesticides, and which may be a potential source of more complex materials.
The finding opens a new pathway for chemical discoveries, they say, and widens the possibilities for addressing environmental problems by transforming greenhouse gases into useful products.
The new study was published on March 7 in the journal Chem.
“Most of our fuels and commodity chemicals are currently derived from fossil fuels,” said Hazari, the John Randolph Huffman Professor of Chemistry, and chair of chemistry, in Yale’s Faculty of Arts and Sciences (FAS). “Their combustion contributes to global warming and their extraction can be environmentally damaging. Therefore, there is a pressing need to explore alternative chemical feedstocks.”
Hazari, who is also a member of the Yale Center for Natural Carbon Capture, and Mayer, the Charlotte Fitch Roberts Professor of Chemistry in FAS, are co-corresponding authors of the study. They are also part of the Center for Hybrid Approaches in Solar Energy to Liquid Fuels (CHASE), a solar energy research hub based at the University of North Carolina-Chapel Hill.
The challenges for transforming CO2 into usable products—on an industrial scale—are formidable. Such processes require new catalysts that work under milder conditions (less extreme temperatures and pressures) and exhibit higher productivity and stability than currently available catalysts.
For the new study, the research team focused on a relatively under-explored type of catalytic system called an immobilized molecular catalyst. This is a system featuring a molecular catalyst that is attached to a solid support material.
The researchers developed molecular manganese catalysts that were attached to semiconducting, thermally oxidized porous silicon. When exposed to light, the silicon absorbs the light and transfers electrons to the manganese catalyst, which then converts CO2 to formate.
“Formate is a very appealing product, as it is a potential stepping-stone to materials used industrially in very large quantities,” Mayer said. “Our work here opens the door to the use of readily available porous silicon as a support for molecular catalysts, in part because it establishes that the presence of a thin oxide layer improves catalyst selectivity and stability.”
The researchers had previously worked with hydride-terminated porous silicon, said Eleanor Stewart-Jones, a graduate student in chemistry at Yale and co-lead author of the study.
“There’s a rich literature studying the modification of porous silicon surfaces,” she said. “Knowing that these surface modifications can be used to tune catalysis will hopefully be impactful for future hybrid catalysts using porous silicon.”
The researchers also noted that the discovery may have applications for catalysts that work with other chemical feedstocks, beyond CO2.
More information: Young Hyun Hong et al, Photoelectrocatalytic reduction of CO2 to formate using immobilized molecular manganese catalysts on oxidized porous silicon, Chem (2025). DOI: 10.1016/j.chempr.2025.102462
Scientists have achieved the first real-time visualization of how excited-state aromaticity emerges within just hundreds of femtoseconds and then triggers a molecule to change from bent to planar structure in a few picoseconds.
By combining ultrafast electronic and vibrational spectroscopies, the team captured these fleeting structural changes at the molecular level and showed that aromaticity appears before—and then drives—the structural planarization. Their findings lay the groundwork for designing more efficient photoactive materials, such as sensors and light-driven molecular switches, by leveraging the power of aromaticity in excited states.
The study is published in the Journal of the American Chemical Society. The research was led by Hikaru Kuramochi, Associate Professor at the Institute for Molecular Science/SOKENDAI.
Aromaticity is a foundational concept in chemistry describing the enhanced stability of cyclic molecules whose electrons are delocalized. Although most discussions have focused on molecules in their ground state, the concept of excited-state aromaticity has recently been extensively utilized in predicting the structural change and designing the chemical reactivities induced by photoexcitation.
While the dynamic properties of excited-state aromaticity have been studied intensively in the past, these have primarily focused on molecules in a near-equilibrium state, leaving the precise timing and interplay between excited-state aromaticity and structural changes poorly understood. Directly visualizing these ultrafast motions is crucial for designing photoactive materials, such as sensors, adhesives, and switches.
The team used a combination of femtosecond transient absorption and time-resolved impulsive stimulated Raman spectroscopy (TR-ISRS)—an advanced time-domain Raman technique that covers vibrational frequencies from terahertz to 3000 cm⁻¹ with femtosecond temporal resolution—to capture ultrafast snapshots of a newly synthesized cyclooctatetraene (COT)-based flapping molecule called TP-FLAP.
By exciting TP-FLAP with a femtosecond laser pulse, then probing its evolving vibrational signals, they could see exactly when and how the molecule’s central COT ring planarized. Isotope labeling with ¹³C at the central ring allowed the researchers to confirm which specific vibrational mode accompanied the bent-to-planar transition.
Initial measurements revealed a sub-picosecond (≈590 fs) electronic relaxation that imparts aromatic character to the bent molecule’s excited state. The molecule then undergoes planarization in a few picoseconds as indicated by a frequency shift in the ring’s carbon-carbon stretching vibration.
With the help of the isotope labeling (¹³C), a telltale shift in the key C=C stretching frequency was unambiguously shown, confirming that the ring’s planarization drives the observed vibrational changes. Calculations of aromaticity indices (e.g., nucleus-independent chemical shifts, NICS) further support that the system is already aromatic in the bent excited state and becomes even more aromatic as it undergoes planarization.
This study provides the first direct observation of nonequilibrium structural changes governed by excited-state aromaticity. It conclusively shows that aromaticity can emerge within hundreds of femtoseconds, preceding—and then facilitating—the picosecond-scale flattening of the molecule.
Beyond deepening our understanding of fundamental light-driven processes, these insights help guide the rational design of photoactive materials, including molecular sensors, tunable fluorescence probes, and photoresponsive adhesives. The TR-ISRS method’s ability to track vibrational modes in real time offers a new avenue for exploring other systems featuring excited-state (anti)aromaticity and complex conformational changes.
More information: Yusuke Yoneda et al, Excited-State Aromatization Drives Nonequilibrium Planarization Dynamics, Journal of the American Chemical Society (2025). DOI: 10.1021/jacs.4c18623
The environmentally harmful greenhouse gas carbon dioxide, or CO₂ for short, can be converted into valuable chemical products such as carbon monoxide (CO) or ethanol by means of electrochemical reduction—electrolysis. These can be used as raw materials for industry or for the sustainable provision of energy. However, a key obstacle to the long-term stability of this technology is the water and salt management within the electrolytic cell in which the chemical reaction takes place.
The research team led by Dr. Joey Disch and PD Dr. Severin Vierrath from Hahn-Schickard and the University of Freiburg, in collaboration with the French Institut Laue-Langevin in Grenoble, has made significant progress in understanding the distribution of water during CO₂ electrolysis. Their study was first published in the ACS Energy Letters and has now been featured as a Research Highlight in the February issue of Nature Catalysis.
The study uses high-resolution neutron imaging—one of the most powerful methods for directly investigating water transport in electrolyzers—to visualize the transport mechanisms during the pulsed operation of a CO₂ electrolyzer.
With a spatial resolution of 6 μm, this method allows a highly precise investigation of water distribution and salt formation under realistic operating conditions (400 mA cm⁻² at a cell voltage of 3.1 V and a Faradaic efficiency for CO of 95%). In contrast to X-rays, neutrons easily penetrate even metallic components, while making hydrogen and thus water-containing structures highly visible.
The results show a significant stabilization of the electrolyzer during pulsed operation, in which the cell potential is periodically set to a potential below the onset of reduction for a short time. Neutron imaging provides an explanation for the stabilization and illustrates that during the brief interruptions in operation, the water content in the gas diffusion layer increases, which promotes the breakdown of obstructive salt deposits.
Electrochemical CO₂ reduction opens up promising prospects for a sustainable transformation of the chemical industry. In particular, CO₂ electrolysis for the production of carbon monoxide is on the threshold of industrial application: Electrolysis cells with anion exchange membranes are already impressing with remarkable efficiency thanks to optimized reactant management and minimized resistance losses.
These findings thus provide valuable information for optimizing the design and operation of CO₂ electrolyzers, enhancing their efficiency and long-term stability, and facilitating the removal of the harmful greenhouse gas CO₂ from the environment.
More information: Luca Bohn et al, High-Resolution Neutron Imaging of Water Transport in CO2 Electrolysis during Pulsed Operation, ACS Energy Letters (2025). DOI: 10.1021/acsenergylett.4c03003
From smartphones to wind turbines, rare earth elements (REEs) are an essential part of the hardware in many advanced technologies. These elements, which include the lanthanides along with scandium and yttrium, are the backbone of industries that rely on unique properties such as luminescence, magnetism and catalytic ability. In fact, as our world moves toward more sustainable energy solutions and increasingly sophisticated technologies, the demand for REEs is projected to grow substantially.
There’s one catch, however: REEs are difficult to extract and even harder to separate. These elements, despite their name, aren’t actually rare in terms of abundance. What makes them “rare” is their dispersion throughout the Earth’s crust and their chemical similarities, which make them incredibly challenging to isolate from one another.
Current separation methods—largely reliant on toxic solvents like kerosene—are not only inefficient, but also harmful to people and the environment. Additionally, while the U.S. once dominated REE mining and production, environmental restrictions on current separation methods have limited domestic production.
Kathleen Stebe, Richer & Elizabeth Goodwin Professor in Chemical and Biomolecular Engineering (CBE), is tackling this challenge head-on with a collaborative group of researchers across five institutions under the support of a grant from the Department of Energy. Stebe is leading a groundbreaking research initiative that aims to create an eco-friendly, bioinspired process for separating REEs that would also avoid shipping semi-processed REEs to other countries for purification.
“Current separation methods use kerosene and extractants-molecules that bind the REE cations, a positively charged particle, that create issues, both environmentally and in terms of efficiency,” says Stebe. “The separation process is not selective enough to efficiently separate lanthanides, meaning that it has to be repeated many times to achieve REEs in sufficient purity. The whole method is cumbersome and creates unnecessary waste.”
Stebe, along with a team of researchers from Penn, the City College of New York, the University of Illinois Chicago, Northwestern University and the University of Chicago, look to human biology to find the molecule best suited for the job of separation: peptides.
Bioinspired interfaces: Drawing on nature’s expertise
In nature, organisms have evolved proteins that selectively bind to specific ions, despite their similar properties. A perfect example of this is calcium-binding proteins in the human body, which can distinguish between calcium and magnesium ions, even though both have the same charge.
“We are applying this concept to create a similar level of selectivity for rare earth elements,” says collaborator E. James Petersson, professor of chemistry, biochemistry and biophysics at Penn’s School of Arts & Sciences. “By using peptide-based molecules—specifically, a truncated version of the EF-hand motif, which is naturally found in calcium-binding proteins—we are designing molecules that can selectively bind to specific rare earth elements.”
This EF-hand motif refers to the structure and mechanism through which these naturally occurring proteins and peptides are able to differentiate between two very similar molecules.
“The structure resembles a hand,” says Stebe, “and each ‘finger’ of the hand is laden with a carboxyl or carbonyl group that binds to cations floating around in solution. It’s a beautiful and complex structure that can recognize the nuanced and subtle differences between two nearly indistinct cations, and then capture and hold onto whichever cation it is ‘looking’ for. This is extremely important for separating REEs, which differ in size by only one-tenth of an angstrom.”
In the team’s recent study published in the Proceedings of the National Academy of Sciences, they found that EF-hand-containing peptides could bind to the peptide-cation complex and capture it at the aqueous-air interface. The vision includes using bubbles to separate specific lanthanides from a mixture. Once bound to the peptides in an aqueous solution, the REEs will rise to the surface, where they are trapped in a foam at the water-air interface, a separation technique called ion foam flotation.
“My primary area of research is in interfacial science, studying the adsorption of surface-active molecules—surfactants and soap molecules—to the air-water interface,” says co-author Charles Maldarelli, professor of chemical engineering at The City College of New York. “This study gave me the opportunity to apply my expertise to the adsorption of peptides and peptide-metal complexes at the interface.”
Felipe Jimenez-Angeles, research associate professor at Northwestern University, performed many of the molecular dynamics simulations in this study. “I am fascinated that these peptides can separate ions that only differ by a few tenths of an Angstrom in diameter via the differences in the electrostatic forces at the atomic scale. The water-soluble peptide reconfigures when it captures the ion and becomes insoluble in water, resulting in its adsorption to the air-water interface.”
The team’s next steps in this research will be investigating how to scale this process, allowing them to isolate target REEs and collect them at usable quantities in a way that is much more efficient and environmentally friendly.
The collaborative effort behind the innovation
What makes this project truly innovative is the collaboration across multiple universities and disciplines. Each institution brings unique expertise to the project, from synthetic chemistry to surface material properties, and even X-ray experiments.
“This is really the first time my lab has used biology to solve chemistry problems,” says Petersson. “Normally, we focus on creating chemical probes to study biology, often looking at neurodegenerative disorders like Parkinson’s disease. But the experience of working on this project has inspired me to explore other biological approaches to chemistry, including adapting disease-related proteins for applications in other fields like energy and sustainability.”
“I have long been interested in molecular interface interactions,” adds Ivan Dmochowski, Professor of Chemistry in Penn’s School of Arts & Sciences. “As an undergraduate, I made molecules that react with the surface of glass and gold, and studied the resulting monolayers that formed. Later I started looking at proteins at the air-water interface.”
Other key senior faculty involved in the research include Monica Olvera de la Cruz from Northwestern University, Raymond Tu from CCNY, Mark Schlossman from the University of Illinois at Chicago, and Daeyeon Lee, Ravi Radhakrishnan and Cesar de la Fuente at the University of Pennsylvania.
“It has been rewarding to both contribute to and learn from this effort,” continues Dmochowski. “To solve really challenging, societally relevant problems in 2025, we will need a wide range of technical expertise, and I am excited to continue working with this team of collaborators to do that.”
Looking ahead: The future of rare earth element recovery
As Stebe’s team continues their work, they are focused on fine-tuning the selectivity of the peptides and optimizing the process for bulk production. Their next steps include using specialized peptides designed by Petersson to enhance the fluorescence of the system, allowing for more precise tracking of the binding events. They also plan to use physics data to inform additional opportunities for improved specificity and look into developing new, synthetic molecules to make this method even more cost-effective and environmentally friendly.
“This is just the beginning,” says Stebe. “We have a lot of exciting new directions to explore, from using synthetic molecules instead of peptides to creating even more selective binding structures. The potential impact of this work goes far beyond just rare earth elements—it could revolutionize the way we approach material separation across many industries.”
More information: Luis E. Ortuno Macias et al, Lanthanide binding peptide surfactants at air–aqueous interfaces for interfacial separation of rare earth elements, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2411763121
