Category: Chemistry

by Wayne Lewis, University of California, Los Angeles

Derek Urwin has a special stake in his work as a cancer control researcher. After undergraduate studies in applied mathematics at UCLA, he became a firefighter. His inspiration to launch a second career as a scientist was the loss of his brother, Isaac, who died of leukemia at only 33 despite no history of cancer in their family. Working with Anastassia Alexandrova, a professor of chemistry and biochemistry at UCLA College, he earned his doctorate.

Urwin is now a UCLA adjunct professor of chemistry—and still a full-time firefighter with the Los Angeles County Fire Department. In a recent publication, his science shed new light on the chemical underpinnings of exposures that may lead to cancer.

When organic substances burn, the smoke carries compounds known as polycyclic aromatic hydrocarbons, or PAHs. PAHs can enter the body through breathing, eating, drinking and skin contact. Because emissions from industry and automobiles are one source, nearly everyone encounters these chemicals in day-to-day life. Certain jobs such as firefighting and coal-tar production expose workers to concentrated doses of PAHs—the same jobs that tend to be associated with increased risk for cancer.

In fact, the International Agency for Research on Cancer has listed many PAHs as probable or possible carcinogens. Only one among these thousands of chemicals, benzo[a]pyrene (B[a]P), is classified as a known carcinogen in humans.

A study by Urwin, Alexandrova and UCLA undergraduate Elise Tran, published in the Proceedings of the National Academy of Sciences, shows that some of B[a]P’s chemical cousins may present more serious risk for cancer. The scientists used computer simulations of molecular interactions to profile what happens when each of 15 PAHs settles onto a spot in the DNA helix commonly linked to cancer-causing mutations. Compared to the known carcinogen, six of the PAHs showed a greater affinity for binding to the mutational hotspot. Those six chemicals also had a higher likelihood of avoiding detection by a crucial mechanism for repairing DNA lesions.

In addition to the new insight into the relative toxicity of PAHs, the research may offer a faster way to filter potentially dangerous chemicals and identify which ones are riskiest to human health. Such findings could inform not only laboratory and population studies but also public policy.

“We hope that our strategy can speed up the process of studying these chemicals,” said Urwin, the study’s first author. “Instead of casting a wide net, this could show exactly where we ought to start the process. Efficient, effective, accurate computational studies can even enhance or accelerate the process of developing policy that improves public and occupational health.”

Urwin also serves as chief science advisor for the International Association of Fire Fighters and was recently appointed to the California Occupational Safety and Health Standards Board.

“Derek’s work as a firefighter made this research possible,” said corresponding author Alexandrova, who is a member of the California NanoSystems Institute at UCLA. “He knows what’s going on in the field very intimately, and that enables us to make the connection to chemistry and the tools that we have. Real-life experience educated us about what to do.”

Credit is also due to Urwin’s intuition. The germ of the investigation was his observation that based on their structure, several PAHs simply looked as though they ought to fit more snugly within the DNA double helix than others, where they insert themselves like a key into a keyhole.

The investigators built on previous research in which they applied an advanced algebraic technique to accurately model PAHs’ atomic interactions. They compared how strongly B[a]P and 14 other PAHs bind to a DNA sequence that is mutated in one-third of all human cancers.

The team plans to apply their computational method to other genetic hot spots related to cancer, as well as to more PAHs and other compounds, including the “forever chemicals” known as PFAS.

With connections to the world of firefighting and science, Urwin also relishes the opportunity for community-based participatory research. In that model, the people being studied help shape the questions being asked, the design and execution of the research, and the dissemination of resulting information to those affected in a way that they understand.

“My fellow firefighters have historically been underserved by the scientific community, not out of disdain, but rather because it’s complicated to conduct research in the midst of emergency service operations,” Urwin said. “Having my feet in both arenas, I want to bring access to scientists, so their research can create a positive impact on health in the fire service community. Science is supposed to make the world better for people, whether it’s firefighters or anyone else.”

More information: Derek J. Urwin et al, Relative genotoxicity of polycyclic aromatic hydrocarbons inferred from free energy perturbation approaches, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2322155121

Journal information: Proceedings of the National Academy of Sciences 

by University of Tsukuba

Conducting polymers exhibit a variety of properties in addition to their conductivity. Research has explored their use in light-emitting devices, electromagnetic wave shielding, and anticorrosion materials. One notable characteristic is paramagnetism.

Researchers at University of Tsukuba have synthesized a conducting polymer, polyaniline, exhibiting perfect diamagnetic properties, which eliminate external magnetic fields within the material. These properties are typically associated with superconductors.

While conducting polymers generally display paramagnetism—where they are weakly attracted to magnetic fields—this breakthrough marks the first step towards developing a conducting material that demonstrates diamagnetism, the opposite of paramagnetic behavior. The results are published in The Journal of Physical Chemistry B.

The research team has previously developed methods for synthesizing various conducting polymers. In this study, they successfully synthesized polyaniline, one of the most commonly studied conductive polymers, in the presence of iron sulfate, imparting perfect diamagnetism—a property that excludes external magnetic fields from the material. This behavior is analogous to that of superconductors and contrasts with the paramagnetism typically found in conducting polymers.

Superconducting Quantum Interference Device measurements of the synthesized polyaniline confirmed that its magnetic susceptibility exhibits a gradual negative shift from approximately 100 K (−173°C), and it demonstrates perfect antiferromagnetism below 24 K (−249°C).

Conducting polymers, which are also organic semiconductors, usually exhibit strong temperature dependence in their electrical conductivity. At lower temperatures, their conductivity typically decreases, while electrical resistance increases.

However, the polyaniline synthesized in this study showed minimal variation in electrical resistance with temperature. A significant reduction in electrical conductivity was only observed at extremely low temperatures.

The discovery of perfect diamagnetism in polyaniline represents a unique phenomenon not observed in conventional organic or inorganic conductive materials. It is plausible that an unconventional mechanism of perfect diamagnetism is at play, potentially leading to novel advancements in the field of conductive polymers.

More information: Hiromasa Goto et al, Perfect Diamagnetism of Polyaniline, The Journal of Physical Chemistry B (2024). DOI: 10.1021/acs.jpcb.4c05317

Journal information: Journal of Physical Chemistry B 

Provided by University of Tsukuba 

by Helmholtz Association of German Research Centres

A team from the Technical University of Berlin, HZB, IMTEK (University of Freiburg) and Siemens Energy has developed a highly efficient alkaline membrane electrolyzer that approaches the performance of established proton-exchange membrane(PEM) electrolyzers. What makes this achievement remarkable is the use of inexpensive nickel compounds for the anode catalyst, replacing costly and rare iridium.

At BESSY II, the team was able to elucidate the catalytic processes in detail using operando measurements, and a theory team (U.S., Singapore) provided a consistent molecular description. In Freiburg, prototype cells were built using a new coating process and tested in operation. The results have been published in the journal Nature Catalysis.

Hydrogen will play a major role in the energy system of the future, as an energy storage medium, a fuel and valuable raw material for the chemical industry. Hydrogen can be produced by electrolysis of water in a virtually climate-neutral way, provided this is done with electricity from solar or wind power.

Scale-up efforts for a green hydrogen economy are currently largely dominated by two systems: proton-conducting membrane electrolysis (PEM) and classic liquid alkaline electrolysis. AEM electrolyzers combine the advantages of both systems and, for example, do not require rare precious metals such as iridium.

Now, research teams from TU Berlin and HZB, together with the Department of Microsystems Engineering (IMTEK) at the University of Freiburg and Siemens Energy, have presented the first AEM electrolyzer that produces hydrogen almost as efficiently as a PEM electrolyzer. Instead of iridium, they used nickel double hydroxide compounds with iron, cobalt or manganese and developed a process to coat them directly onto an alkaline ion exchange membrane.

Insight into molecular processes during electrolysis at BESSY II

During the electrolysis in the cell, they were able to carry out operando measurements at the Berlin X-ray source BESSY II at the LiXEdrom end station. A theory team from Singapore and the U.S. helped to interpret the experimental data.

“This enabled us to elucidate the relevant catalytic-chemical processes at the catalyst-coated membrane, in particular the phase transition from a catalytically inactive alpha phase to a highly active gamma phase and the role of the various O ligands and Ni⁴⁺ centers in the catalysis,” explains Prof. Peter Strasser, TU Berlin.

“It is this gamma phase that makes our catalyst competitive with the current state-of-the-art iridium catalysts. Our work shows important similarities to iridium in the catalytic mechanism, but also some surprising molecular differences.”

The study has thus significantly advanced our understanding of the fundamental catalysis mechanisms of the new nickel-based electrode materials. In addition, the newly developed coating method for the membrane electrode promises excellent scalability. A first fully functional laboratory cell has already been tested at IMTEK. The work lays the foundation for further industrial evaluation and demonstrates that an AEM water electrolyzer can also be highly efficient.

More information: M. Klingenhof et al, High-performance anion-exchange membrane water electrolysers using NiX (X = Fe,Co,Mn) catalyst-coated membranes with redox-active Ni–O ligands, Nature Catalysis (2024). DOI: 10.1038/s41929-024-01238-w

Journal information: Nature Catalysis 

by Duke University

Additive manufacturing (AM) has revolutionized many industries and holds the promise to affect many more in the not too distant future. While people are most familiar with the 3D printers that function much like inkjet printers, another type of AM offers advantages using a different approach: building objects with light one layer at a time.

One such technology is digital light processing (DLP). Widely used in both industrial and dental applications, DLP works by converting a liquid resin into a solid part using light, essentially pulling solid objects out of a shallow pool of resin one layer at a time.

A major challenge to using this 3D printing method, however, is that the resins need to have a low viscosity, almost like water, to function properly at high resolution. Plenty of polymers that would otherwise be useful in DLP printing are solids or too viscous, requiring solvents to dilute them to an appropriate consistency.

But adding these solvents also causes significant drawbacks, like poor dimensional accuracy after printing due to part shrinkage (up to 30%) coupled with residual stress that occurs as the solvent evaporates.

In a paper published in Angewandte Chemie International Edition, researchers at Duke University have invented a new solvent free polymer for DLP printing. Besides eliminating the shrinkage problem, the lack of solvent also results in improved mechanical properties of the part while maintaining the ability to degrade in the body.

“I wanted to create an inherently thin, low-viscosity material for DLP to use for degradable medical devices,” said Maddiy Segal, a MEMS Ph.D. candidate working in the laboratory of Matthew Becker, the Hugo L. Blomquist Distinguished Professor of Chemistry at Duke. “It took a lot of attempts, but eventually I was able to identify optimal monomers and a synthetic technique to create a solvent free polymer that can be used in a DLP printer without any dilution.”

Since the new material is one of the first solvent free resins that can be used in DLP printing, Segal was interested in testing the properties of parts made with it. She was excited to discover that the test parts did not shrink or distort at all, and in general, they were also stronger and more durable than those made with solvents. According to her findings, this is one of the first empirical demonstrations of increased mechanical properties from eliminating solvent use in DLP 3D printing of degradable polymers.

To create her new polymer, Segal analyzed the structure and properties of existing resins developed by the Becker Lab and others and modified the monomers and chain length in a step-by-step empirical approach to achieve the desired low-viscosity polymers. She essentially used a “guess and check” approach, adjusting the polymer’s monomers or “recipes” until she found a combination that worked.

The process isn’t entirely dissimilar from cooking a meal. It involves mixing specific combinations of ingredients, heating them, and then testing the results until achieving the desired outcome. In total, Segal experimented with about 60 different combinations before finally making the product she had been hoping for.

“Besides making a material that didn’t shrink and was stronger, I also wanted it to be useful for medical applications,” Segal said. “I’m trying to make prototype devices that are both biocompatible and degradable. Eliminating toxic solvents from the process will help me do that.”

Segal’s ultimate goal with this work is to apply this technique to biodegradable medical implants. Some materials used to make temporary medical implants today are not degradable and require multiple surgeries to not only implant them, but also remove them. Through her research, Segal aims to develop implants that can be degraded through the body’s natural processes.

Devices fabricated from this material could be implanted and designed to degrade naturally over time, eliminating the need for additional surgeries to remove the device. It could also potentially be used as a bone adhesive to hold fractures together temporarily or in soft robotics applications, where a soft, degradable material is needed.

“This kind of material is what makes this particular application the primary goal of my work,” Segal said. “And in reality, this technique could be used for any sort of implant that you would want to degrade after some time and not stay there forever.”

More information: Maddison I. Segal et al, Synthesis and Solvent Free DLP 3D Printing of Degradable Poly(Allyl Glycidyl Ether Succinate), Angewandte Chemie International Edition (2024). DOI: 10.1002/anie.202414016

Journal information: Angewandte Chemie International Edition 

by Stanford University

As California transitions rapidly to renewable fuels, it needs new technologies that can store power for the electric grid. Solar power drops at night and declines in winter. Wind power ebbs and flows. As a result, the state depends heavily on natural gas to smooth out highs and lows of renewable power.

“The electric grid uses energy at the same rate that you generate it, and if you’re not using it at that time, and you can’t store it, you must throw it away,” said Robert Waymouth, the Robert Eckles Swain Professor in Chemistry in the School of Humanities and Sciences.

Waymouth is leading a Stanford team to explore an emerging technology for renewable energy storage: liquid organic hydrogen carriers (LOHCs). Hydrogen is already used as fuel or a means for generating electricity, but containing and transporting it is tricky.

“We are developing a new strategy for selectively converting and long-term storing of electrical energy in liquid fuels,” said Waymouth, senior author of a study detailing this work in the Journal of the American Chemical Society. “We also discovered a novel, selective catalytic system for storing electrical energy in a liquid fuel without generating gaseous hydrogen.”

Liquid batteries

Batteries used to store electricity for the grid—plus smartphone and electric vehicle batteries—use lithium-ion technologies. Due to the scale of energy storage, researchers continue to search for systems that can supplement those technologies.

Among the candidates are LOHCs, which can store and release hydrogen using catalysts and elevated temperatures. Someday, LOHCs could widely function as “liquid batteries,” storing energy and efficiently returning it as usable fuel or electricity when needed.

The Waymouth team studies isopropanol and acetone as ingredients in hydrogen energy storage and release systems. Isopropanol—or rubbing alcohol—is a high-density liquid form of hydrogen that could be stored or transported through existing infrastructure until it’s time to use it as a fuel in a fuel cell or to release the hydrogen for use without emitting carbon dioxide.

Yet methods to produce isopropanol with electricity are inefficient. Two protons from water and two electrons can be converted into hydrogen gas, then a catalyst can produce isopropanol from this hydrogen.

“But you don’t want hydrogen gas in this process,” said Waymouth. “Its energy density per unit volume is low. We need a way to make isopropanol directly from protons and electrons without producing hydrogen gas.”

Daniel Marron, lead author of this study who recently completed his Stanford Ph.D. in chemistry, identified how to address this issue. He developed a catalyst system to combine two protons and two electrons with acetone to generate the LOHC isopropanol selectively, without generating hydrogen gas. He did this using iridium as the catalyst.

A key surprise was that cobaltocene was the magic additive. Cobaltocene, a chemical compound of cobalt, a non-precious metal, has long been used as a simple reducing agent and is relatively inexpensive. The researchers found that cobaltocene is unusually efficient when used as a co-catalyst in this reaction, directly delivering protons and electrons to the iridium catalyst rather than liberating hydrogen gas, as was previously expected.

A fundamental future

Cobalt is already a common material in batteries and in high demand, so the Stanford team is hoping their new understanding of cobaltocene’s properties could help scientists develop other catalysts for this process. For example, the researchers are exploring more abundant, non-precious earth metal catalysts, such as iron, to make future LOHC systems more affordable and scalable.

“This is basic fundamental science, but we think we have a new strategy for more selectively storing electrical energy in liquid fuels,” said Waymouth.

As this work evolves, the hope is that LOHC systems could improve energy storage for industry and energy sectors or for individual solar or wind farms.

And for all the complicated and challenging work behind the scenes, the process, as summarized by Waymouth, is actually quite elegant, “When you have excess energy, and there’s no demand for it on the grid, you store it as isopropanol. When you need the energy, you can return it as electricity.”

Additional Stanford co-authors are Conor Galvin, Ph.D. ’23, and Ph.D. student Julia Dressel. Waymouth is also a member of Stanford Bio-X and the Stanford Cancer Institute, a faculty fellow of Sarafan ChEM-H, and an affiliate of the Stanford Woods Institute for the Environment.

by Karyn Hede, Pacific Northwest National Laboratory

Cooks love stainless steel for its durability, rust resistance and even cooking when heated. But few know the secret that makes stainless steel so popular. It’s the metal chromium in stainless steel, which reacts with oxygen in the air to form a stable and protective thin coating for protecting the steel underneath.

These days, scientists and engineers are working to design alloys that can resist extreme environments for applications such as nuclear fusion reactors, hypersonic flights and high-temperature jet engines. For such extreme applications, scientists are experimenting with complex combinations of many metals mixed in equal proportions in what are called multi-principal element alloys or medium- to high-entropy alloys. These alloys aim to achieve design goals such as strength, toughness, resistance to corrosion and so on.

Specifically, researchers seek alloys resistant to corrosion that can happen when metals react with oxygen in the atmosphere, a process called oxidation. These alloys are typically tested in a “cook-and-look” procedure where alloy materials are exposed to high-temperature oxidation environments to see how they respond.

But now, a multidisciplinary research team led by scientists at the Department of Energy’s Pacific Northwest National Laboratory and North Carolina State University combined atomic-scale experiments with theory to create a tool to predict how such high-entropy alloys will behave under high-temperature oxidative environments. The research, published in the journal Nature Communications, offers a road map toward rapid design and testing cycles for oxidation-resistant complex metal alloys.

“We are working toward developing an atomic-scale model for material degradation of these complex alloys, which then can be applied to design next-generation alloys with superior resistance to extreme environments for a wide variety of applications such as the aerospace and nuclear power industries,” said Arun Devaraj, co-principal investigator of the study and a PNNL materials scientist specializing in understanding metal degradation in extreme environments.

“The goal here is to find ways to rapidly identify medium- to high-entropy alloys with the desired properties and oxidation resistance for your chosen application.”

A complex alloy recipe

For their recent experiments, the research team studied the degradation of a high-entropy alloy with equal amounts of the metals cobalt, chromium, iron, nickel and manganese (CoCrFeNiMn, also called the Cantor alloy). The research team examined oxide formed on the Cantor alloy using a variety of advanced atomic-scale methods to understand how each element arranges itself in the alloy and the oxide.

They discovered that chromium and manganese tend to migrate quickly toward the surface and form stable chromium and manganese oxides. Subsequently, iron and cobalt diffuse through these oxides to form additional layers.

By adding a small amount of aluminum, they discovered that aluminum oxide can act as a barrier for other elements migrating to form the oxide, thereby reducing the overall oxidation of the aluminum-containing Cantor alloy and increasing its resistance to degradation at high temperatures.

“This work sheds light on the mechanisms of oxidation in complex alloys at the atomic scale,” said Bharat Gwalani, co-corresponding author of the study. Gwalani began the study while a scientist at PNNL and continued the research in his current role as an assistant professor of materials science and engineering at North Carolina State University. He added, “by understanding the fundamental mechanisms involved, this work gives us a deeper understanding of oxidation across all complex alloys.”

Predictive models

“Right now there are no universally applicable governing models to extrapolate how a given complex, multi-principal element alloy will oxidize and degrade over time in a high-temperature oxidation environment,” said Devaraj. “This is a substantial step in that direction.”

The team’s careful analysis revealed some universal rules that can predict how the oxidation process will proceed in these complex alloys. Computational colleagues from NCSU developed a model called the Preferential Interactivity Parameter for early prediction of oxidation behavior in complex metal alloys.

Ultimately, the research team expects to expand this research to develop complex alloys with exceptional high-temperature properties, and to do so very quickly by rapid sampling and analysis. The ultimate goal is to choose a combination of elements that favor the formation of an adherent oxide, said Devaraj. “You know oxide formation will happen, but you want to have a very stable oxide that will be protective, that would not change over time, and would withstand extreme heat inside a rocket engine or nuclear reactors.”

A next step will be to introduce automated experimentation and integrate additive manufacturing methods, along with advanced artificial intelligence, to rapidly evaluate promising new alloys. That project is now getting underway at PNNL as a part of the Adaptive Tunability for Synthesis and Control via the Autonomous Learning on Edge (AT SCALE) Initiative.

“That kind of discovery loop for materials discovery will be very relevant for further expanding our knowledge of these novel alloys,” said Devaraj, who also has a joint faculty appointment at the Colorado School of Mines.

In addition to Gwalani and Devaraj, PNNL scientists Sten Lambeets, Matthew Olszta, Anil Krishna Battu and Thevuthasan Suntharampillai contributed; as well as Martin Thuo, Aram Amassian, Andrew Martin, Aniruddha Malakar, and Boyu Guo of NCSU; Elizabeth Kautz, an assistant professor of nuclear engineering at North Carolina State, who also has a joint appointment with PNNL; Feipeng Yang and Jinghua Guo of Lawrence Berkeley National Laboratory; and Ruipeng Li of Brookhaven National Laboratory.

To investigate the arrangement of atoms within the samples, the research team used in situ atom probe tomography at PNNL. These results were correlated with electron microscopy and synchrotron-based grazing incidence wide-angle X-ray scattering at the National Synchrotron Light Source II, BNL, and X-ray absorption measurements conducted at the Advanced Light Source, LBNL.

by US Department of Energy

For the first time in history, scientists have measured radium’s bonding interactions with oxygen atoms in an organic molecule. Scientists have not measured this bonding before because radium-226 is available only in small amounts and it is highly radioactive (radium is one million times more radioactive than the same mass of uranium), making it challenging to work with.

The findings are published in the journal Nature Chemistry.

Using oxygen as the donor atom, the researchers developed a way to synthesize and crystallize the radium complex rapidly and on a small scale. Next, they measured the X-ray diffraction pattern of the complex. This pattern is created by the complex’s crystal structure and reveals its structure and bonding characteristics.

Certain radium isotopes show promise for targeted alpha therapy treatment for cancers. For this type of treatment, radium must be bonded to another molecule, called a “chelator,” and delivered directly to tumors in the body. There, the radium gives off powerful radiation that travels only a very short distance to attack the tumor and leaves surrounding cells unharmed.

When developing these chelators, scientists typically use barium because it is chemically similar to radium. However, this study showed that radium is quite different from barium. The result gives scientists information that may help them use radium in future cancer treatments.

Working with radium, which is highly radioactive, required the researchers to develop a process for synthesis and crystallization on a nanogram scale.

Their success using this technique to characterize radium potentially allows scientists to learn exactly how radium binds to other elements—oxygen or nitrogen, for example. Since nitrogen and oxygen are elements typically present in chelators, and radium interacts with them during bonding, this information will be helpful for developing chelators to carry radium to cancer sites in targeted alpha therapy treatment.

This work also demonstrates significant differences between radium and barium in how they interact with chelators, suggesting that barium is not always a good stand-in for radium when developing these chelators. The methods the researchers used to characterize and analyze radium potentially could be used to learn about other challenging radioactive complexes.

by Zhang Nannan, Chinese Academy of Sciences

Point-of-care testing (POCT) devices show great advantages over conventional diagnostic tests in being accessible to patients and providing timely diagnostic information. The global POCT market has grown remarkably over the past few decades. Distance-based devices are attracting great interest due to their simplicity, affordability, and ease of application.

Researchers at the Suzhou Institute of Biomedical Engineering and Technology (SIBET) of the Chinese Academy of Sciences have proposed a distance-based visual miRNA biosensor based on a DNA hydrogel system. The results of the study, titled “Distance-Based Visual miRNA Biosensor with Strand Displacement Amplification-Mediated DNA Hydrogel Assembly,” were published in ACS Materials Letters.

The target miRNA-initiated strand displacement amplification process will produce abundant single-stranded DNA, which are essential probes for the linking of the three-way junction scaffold of the hydrogel.

The phase transition of the solution is confirmed by elastic and electrochemical techniques. A distance-based paper biosensing method is thus set up by establishing the relationship between the seepage flow distance along the strip and the initial miRNA concentration.

Due to the strand displacement amplification, the biosensor is not only simple but also highly sensitive with a detection limit down to 1 fM.

Since the three-dimensional DNA hydrogel provides abundant binding sites, the detection range is quite wide, according to the researchers.

The biosensor is shown to be highly selective, and the results of human serum analysis are consistent with standard quantitative reverse transcription-PCR.

“This approach has the advantages of convenient operation and low cost, which meets the requirements of point-of-care testing,” said Miao Peng, lead author of the study. “It is promising as a convenient tool for miRNA-related biological studies and clinical diagnosis.”

by Anne Trafton, Massachusetts Institute of Technology

In the movie “Jurassic Park,” scientists extracted DNA that had been preserved in amber for millions of years, and used it to create a population of long-extinct dinosaurs.

Inspired partly by that film, MIT researchers have developed a glassy, amber-like polymer that can be used for long-term storage of DNA, whether entire human genomes or digital files such as photos.

Most current methods for storing DNA require freezing temperatures, so they consume a great deal of energy and are not feasible in many parts of the world. In contrast, the new amber-like polymer can store DNA at room temperature while protecting the molecules from damage caused by heat or water.

The researchers showed that they could use this polymer to store DNA sequences encoding the theme music from Jurassic Park, as well as an entire human genome. They also demonstrated that the DNA can be easily removed from the polymer without damaging it.

“Freezing DNA is the number one way to preserve it, but it’s very expensive, and it’s not scalable,” says James Banal, a former MIT postdoc. “I think our new preservation method is going to be a technology that may drive the future of storing digital information on DNA.”

Banal and Jeremiah Johnson, the A. Thomas Geurtin Professor of Chemistry at MIT, are the senior authors of the study, published in the Journal of the American Chemical Society. Former MIT postdoc Elizabeth Prince and MIT postdoc Ho Fung Cheng are the lead authors of the paper.

Capturing DNA

DNA, a very stable molecule, is well-suited for storing massive amounts of information, including digital data. Digital storage systems encode text, photos, and other kinds of information as a series of 0s and 1s. This same information can be encoded in DNA using the four nucleotides that make up the genetic code: A, T, G, and C. For example, G and C could be used to represent 0 while A and T represent 1.

DNA offers a way to store this digital information at very high density: In theory, a coffee mug full of DNA could store all of the world’s data. DNA is also very stable and relatively easy to synthesize and sequence.

In 2021, Banal and his postdoc advisor, Mark Bathe, an MIT professor of biological engineering, developed a way to store DNA in particles of silica, which could be labeled with tags that revealed the particles’ contents. That work led to a spinout called Cache DNA.

One downside to that storage system is that it takes several days to embed DNA into the silica particles. Furthermore, removing the DNA from the particles requires hydrofluoric acid, which can be hazardous to workers handling the DNA.

To come up with alternative storage materials, Banal began working with Johnson and members of his lab. Their idea was to use a type of polymer known as a degradable thermoset, which consists of polymers that form a solid when heated. The material also includes cleavable links that can be easily broken, allowing the polymer to be degraded in a controlled way.

“With these deconstructable thermosets, depending on what cleavable bonds we put into them, we can choose how we want to degrade them,” Johnson says.

For this project, the researchers decided to make their thermoset polymer from styrene and a cross-linker, which together form an amber-like thermoset called cross-linked polystyrene. This thermoset is also very hydrophobic, so it can prevent moisture from getting in and damaging the DNA. To make the thermoset degradable, the styrene monomers and cross-linkers are copolymerized with monomers called thionolactones. These links can be broken by treating them with a molecule called cysteamine.

Because styrene is so hydrophobic, the researchers had to come up with a way to entice DNA—a hydrophilic, negatively charged molecule—into the styrene.

To do that, they identified a combination of three monomers that they could turn into polymers that dissolve DNA by helping it interact with styrene. Each of the monomers has different features that cooperate to get the DNA out of water and into the styrene. There, the DNA forms spherical complexes, with charged DNA in the center and hydrophobic groups forming an outer layer that interacts with styrene. When heated, this solution becomes a solid glass-like block, embedded with DNA complexes.

The researchers dubbed their method T-REX (Thermoset-REinforced Xeropreservation). The process of embedding DNA into the polymer network takes a few hours, but that could become shorter with further optimization, the researchers say.

To release the DNA, the researchers first add cysteamine, which cleaves the bonds holding the polystyrene thermoset together, breaking it into smaller pieces. Then, a detergent called SDS can be added to remove the DNA from polystyrene without damaging it.

Storing information

Using these polymers, the researchers showed that they could encapsulate DNA of varying length, from tens of nucleotides up to an entire human genome (more than 50,000 base pairs). They were able to store DNA encoding the Emancipation Proclamation and the MIT logo, in addition to the theme music from “Jurassic Park.”

After storing the DNA and then removing it, the researchers sequenced it and found that no errors had been introduced, which is a critical feature of any digital data storage system.

The researchers also showed that the thermoset polymer can protect DNA from temperatures up to 75 degrees Celsius (167 degrees Fahrenheit). They are now working on ways to streamline the process of making the polymers and forming them into capsules for long-term storage.

Cache DNA, a company started by Banal and Bathe, with Johnson as a member of the scientific advisory board, is now working on further developing DNA storage technology. The earliest application they envision is storing genomes for personalized medicine, and they also anticipate that these stored genomes could undergo further analysis as better technology is developed in the future.

“The idea is, why don’t we preserve the master record of life forever?” Banal says. “Ten years or 20 years from now, when technology has advanced way more than we could ever imagine today, we could learn more and more things. We’re still in the very infancy of understanding the genome and how it relates to disease.”

by Martha Höhne, Leibniz Institute for Catalysis

A catalyst developed at LIKAT in Rostock opens up new avenues in the synthesis of fine chemicals for pharmaceuticals, agrochemicals and household chemicals, for example. Its effect is based on isolated copper atoms applied to a solid carrier material around which the reaction solution flows.

This heterogeneous catalysis, so called because the aggregate states of the catalyst (solid) and the starting materials (liquid) differ, is highly unusual in the production of pharmaceuticals, for example. The researchers report on the new approach in the journal Chem.

Hot topic: Heterogeneous instead of homogeneous

In the production of fine chemicals, chemists usually use the classic workhorse, homogeneous catalysis: starting materials, catalyst and end product are in a liquid mix (homogeneous, i.e. in the same aggregate state) in one vessel. One advantage of this catalysis is the mild reaction temperatures, which are gentle on the sensitive structures of these complex molecules.

However, homogeneous catalysis has decisive disadvantages. This is why one of the “hot topics” in chemistry is to replace these processes with heterogeneous procedures. Two Humboldt Fellows at the Leibniz Institute for Catalysis in Rostock have succeeded in doing this for a single step within a multi-stage reaction cascade that fine chemicals usually undergo during their production.

Dr. Qiang Wang and Dr. Haifeng Qi developed a heterogeneous copper catalyst and were able to use it to re-establish important bonds between carbon and other chemical elements in numerous complex molecules at moderate temperatures of 60 degrees Celsius.

Single-atom structure on MOFs

When developing their catalyst, they applied the copper atoms to the carrier material in isolated form, i.e. individually. This so-called single-atom structure enabled Wang and Qi to enormously increase the precision of their catalyst, which chemists refer to as selectivity. Their copper catalyst has also outperformed the homogeneous process in terms of yield.

“Individually, copper atoms offer the reaction environment a much larger surface area than when they are connected in clusters or nanoparticles,” say Dr. Kathrin Junge and Prof. Jagadeesh Rajenahally, explaining the principle.

Junge and Rajenahally are co-authors of the Chem paper and supervised Haifeng Qi and Qiang Wang. The two Humboldt Fellows are now working in other research groups in China and the UK. Kathrin Junge explains the significance of her research, “Active ingredients, vitamins and fragrances are often modeled on nature and are created through total synthesis, which in turn can involve a dozen or more reaction steps.”

After each step, the substances must be separated, purified and prepared for the next reaction stage. However, the catalysts, usually organometallic complexes, are difficult to recover from the homogeneous reaction solutions. And metal impurities represent a real hurdle for the approval of drugs, as the authors write in the original paper.

The two Humboldt fellows circumvented this problem by stably bonding their metal to a solid carrier material. They used organometallic framework structures as carriers, which have been making a name for themselves in chemistry for several years under the name MOFs.

“These MOFs contain structures similar to those of ligands in homogeneous catalysts,” explains Dr. Junge. Their function is simulated to a certain extent with the help of the corresponding structure in the heterogeneous copper catalyst.

Substances selected for specific applications

Qiang Wang and Haifeng Qi demonstrated the functionality of their heterogeneous catalyst using a variety of complex molecules that are used in organic synthesis chemistry. For example, for the production of pharmaceuticals, vitamins in animal feed production and fragrances in household chemistry.

Dr. Junge said, “The two colleagues have thus shown that their research work really does have potential applications in mind.” Or, as the original paper puts it, “The use of more stable heterogeneous materials is a model for future catalysis in the field of organic syntheses.”