Sandro Botticelli, the Lamentation of Christ, with indication of sampling positions for binding medium analyses. Credit: Bavarian State Painting Collections, Munich.
A team of chemical engineers affiliated with several institutions in Europe has determined why Old Masters of the 16th, 17th, and early 18th centuries added egg yolk to their oil-based paints. In their study, reported in the journal Nature Communications, the group added fresh egg yolk to the types of oils used by Renaissance painters and tested them to see changes it made to their properties.
For many years, historians have known that the Old Masters of the Renaissance, such as Sandro Botticelli or Leonardo da Vinci, added proteins such as egg yolk to their oil-based paints—creating a medium known as egg tempera—but no one knew why. In this new effort, the chemists set themselves the task of solving the mystery.
The work involved creating two types of oil-based paints, both with yolk added. One mixture consisted of nothing but yolk and oil. The other had yolk, oil and pigments to add coloring. The team also created similar paints without using egg yolk. The group then used the paints to create paintings that could be used for testing purposes. Such tests included taking measurements of moisture amounts and movement, oxidation, time to dry and heat capacity.
The researchers found that adding yolk helped to create stronger bonding between pigment particles, which made for stiffer paint. And that, they noted, would have been ideal for use in impasto painting, where the ink is applied thickly to give it a three-dimensional quality. The group also found that adding yolk reduced wrinkling of the paint, helping it to retain the shape applied by the painter—and helped to protect the paint against exposure to high humidity. Antioxidants in the yolk also helped to prevent yellowing.
Adding egg yolk also allowed the painter, the team found, to add more pigment to the oil, which in turn, helped to create more vivid images.
The research group found that there was one a downside to adding yolk—the paint takes longer to dry, which means the painter has to wait longer to add another coat.
More information: Ophélie Ranquet et al, A holistic view on the role of egg yolk in Old Masters’ oil paints, Nature Communications (2023). DOI: 10.1038/s41467-023-36859-5
Nickel-iron hydrogenase, described by researchers as “one of nature’s most complicated and beautiful enzymes,” may be crucial in the world’s push toward a renewable energy economy. Credit: Mirica group, University of Illinois at Urbana-Champaign
An ancient biological enzyme known as nickel-iron hydrogenase may play a key role in producing hydrogen for a renewables-based energy economy, researchers have found. Careful study of the enzyme has led chemists from the University of Illinois Urbana-Champaign to design a synthetic molecule that mimics the hydrogen gas-producing chemical reaction performed by the enzyme.
The researchers reported their findings in the journal Nature Communications.
Currently, industrial hydrogen is usually produced by separating hydrogen gas molecules from oxygen atoms in water using a process called electrolysis. To boost this chemical reaction in the industrial setting, platinum metal is used as a catalyst in the cathodes that direct the reaction. However, many studies have shown that the expense and rarity of platinum make it unattractive as the world pushes toward more environmentally sound energy sources.
On the other hand, nature’s nickel-iron hydrogenase enzyme produces hydrogen using earth-abundant metals in its core, said chemistry professor Liviu Mirica, who led the study with graduate student Sagnik Chakrabarti.
“The nickel at the core of the natural enzyme produces hydrogen by reducing protons in water,” Chakrabarti said. “During the catalytic process, the nickel center goes through paramagnetic intermediates, meaning that the intermediates have an unpaired electron—which makes them extremely short-lived.”
Synthetic chemists have made nickel compounds that produce hydrogen for over a decade, Mirica said. While some of these compounds are very efficient at producing hydrogen, the vast majority of them operate via intermediates that are not paramagnetic.
“Researchers are trying to mimic exactly what nature does because it is efficient, and maximizing efficiency is a key challenge to overcome when engineering energy sources,” Mirica said. “Being able to reproduce the paramagnetic intermediate steps that occur in the natural enzyme is what our group is trying to achieve—to increase efficiency and mimic nature.”
To achieve this, the team designed an organic molecule called a ligand that contains electron-donating atoms like nitrogen and sulfur, and can hold the nickel in place and support the two relevant paramagnetic states that produce hydrogen. The key design element that sets this molecule apart from other catalysts is the presence of a carbon-hydrogen bond near the nickel center that is broken and formed again during catalysis. This was crucial in stabilizing the aforementioned paramagnetic states.
“One of the key takeaways from our work is that by using the specially designed ligand in the manner we did, we have successfully united ideas from two fields of inorganic chemistry—bioinorganic and organometallic chemistry—to make nickel complexes that behave similarly to the active site of one of nature’s most beautiful and complicated enzymes,” Chakrabarti said.
In the recent past, several unusual enzymes have been found that feature metal-carbon bonds in their active sites, the researchers said. Such design principles in synthetic complexes could lead to further insights into how nature performs chemistry with small molecules like hydrogen.
Former Illinois researchers Soumalya Sinha, Giang N. Tran and Hanah Na contributed to this study.
More information: Sagnik Chakrabarti et al, Characterization of paramagnetic states in an organometallic nickel hydrogen evolution electrocatalyst, Nature Communications (2023). DOI: 10.1038/s41467-023-36609-7
The graph in the center of this image shows the hybrid photocatalysts, labeled as 1 through 4, and the stark reduction in hexvalent chromium in the research when compared to other photocatalysts. Credit: Polyoxometalates, Tsinghua University Press
Toxic heavy metals found in wastewater have health and safety ramifications for communities affected by pollution. Hexavalent chromium is a dangerous, cancer-causing byproduct of industrial processes that is known to cause birth defects, severe diarrhea, and is linked to kidney, bladder, and liver cancers. Famously, it was the center of the lawsuit dramatized in the film “Erin Brockovich.”
Researchers are trying to find effective ways to remove hexavalent chromium from wastewater and a recently published paper shows how photocatalytic technology may be a solution. Photocatalysis is when light and a catalyst are used to speed up chemical reactions.
The paper was published in Polyoxometalates.
“Rapid industrialization causes an increased release of wastewater containing heavy metal ions. Hexavalent chromium, which has high carcinogenicity and teratogenicity, is widely found in wastewater and can easily enter food chains,” said Yuan-Yuan Ma, a researcher at Hebei Normal University in Shijiazhuang, China. Photocatalysis technology is an appealing solution for removing heavy metals from wastewater because it is sustainable, cost-effective, and environmentally friendly.
“This green approach for the removal of heavy metal ions uses sustainable light energy via hourglass-type phosphomolybdate-based crystalline photocatalysts and develops a strategy for the regulation of photocatalytic performance by adjusting the central metal ions in hourglass-type phosphomolybdate clusters,” said Ma. Researchers chose this particular type of photocatalyst because of its molecular properties and well-defined hourglass-type structure, which give it a wide light absorption ability and the band structure necessary to reduce the levels of hexavalent chromium.
Researchers tested four “hybrid” photocatalysts and compared them to six other photocatalysts. The hybrids had slightly different compositions, but all had the same hourglass-type structure that could be maintained up to 200 degrees Celsius. They had wide visible-light absorption and similar energy band structures. Researchers labeled these as Hybrid 1, 2, 3, and 4. After 80 minutes of exposure to a 10W LED light, hybrid 1 and 3 had around a 90% reduction in hexavalent chromium, while 2 and 4 had around a 74% and 71% reduction in hexavalent chromium respectively.
The hybrids generally performed better than any of the tested photocatalysts. Hybrids 1 and 3, which performed best, both were Mn{P4MO6}2-based hybrids. Hybrids 2 and 4 were Co{P4MO6}2-based. Researchers suspect that the better performance was due to structural differences that gave hybrids 1 and 3 a narrower band gap. “The semiconductor photocatalysts in photocatalytic processes can absorb photons matched with their band gap energy, leading to the conversion of toxic hexavalent chromium to less toxic chromium,” said Ma.
Looking ahead, researchers will focus on improving the design of the photocatalysts, while also planning for how to best bring this technology to a real-world wastewater setting. “Designing effective photocatalysts is the first step to solve heavy metal pollution in water,” said Ma. “We will design more efficient photocatalysts and apply the developed photocatalysts to actual industrial wastewater. We will also expand the treatment range of polluted water sources and strive to realize the practicality of the photocatalyst materials used.”
More information: Xiao-Yu Yin et al, Photoactive hourglass-type M{P 4Mo 6} 2 networks for efficient removal of hexavalent chromium, Polyoxometalates (2023). DOI: 10.26599/POM.2023.9140027
Converting CO2 to Ethanol on Partially Oxidized Ag Nanowires with High Selectivity and Activity. Credit: Science China Press
In a study, published in the journal Science China Chemistry and led by Prof. Pingping Fang (School of Chemistry, Zhejiang University) and Prof. Jianfeng Li (College of Chemistry and Chemical Engineering, Xiamen University), experiments were performed by using an Xplora Raman spectrometer with a 50x microscope objective and an excitation wavelength of 638 nm from a He–Ne laser.
“Due to the proper adsorption energy of CO on the partially oxidized Ag NWs, it is of great significance to correlate the high ethanol selectivity for CO2 electroreduction with the partially oxidized active center. Ag catalysts have been shown to exhibit high selectivity for CO2 electroreduction to CO at low over potentials with depressed H2 evolution. CO is an important intermediate for C-C coupling, therefore, Ag has the potential to exhibit high selectivity for ethanol products by tuning the adsorption energy of CO. This study provides a new insight to design efficient catalysts and investigate the mechanisms to improve the selectivity,” Fang says.
Interestingly, high ethanol FE was obtained on partially oxidized Ag NWs for CO2 electroreduction, and operando EC-SERS combined with DFT calculation explained the mechanisms why partially oxidized Ag NWs exhibited so high ethanol selectivity. The ethanol FE can reach as high as 85% on partially oxidized Ag NWs at −0.95 V vs. RHE. Operando EC-SERS found the high coverage of CO can greatly facilitate the ethanol formation on partially oxidized Ag NWs during CO2 electroreduction.
DFT calculation results show that the adsorption energy of CO on the partially oxidized Ag NWs is higher than that on Cu, and the reaction free energy of CO coupling with *CHO to *COCHO intermediate on partially oxidized Ag NWs is smaller than that on Cu surface, which explains the high ethanol selectivity very well.
Therefore, experiment results, operando EC-SERS and DFT calculations together prove that such partially oxidized Ag NWs can provide high ethanol selectivity for CO2 electroreduction. These results provide new clues for designing Ag based catalysts to improve the ethanol selectivity and mechanism studies.
More information: Qiong Liu et al, Converting CO2 to ethanol on Ag nanowires with high selectivity investigated by operando Raman spectroscopy, Science China Chemistry (2022). DOI: 10.1007/s11426-022-1460-7
An illustration of how next-generation bioimager BIGTUNA simultaneously uses multiple approaches to significantly improve metabolic mapping. Credit: Nathan Johnson, Pacific Northwest National Laboratory
Microbes may be among the smallest living things on Earth, but bioimaging to understand the chemistry that fuels these organisms could reveal important clues about the intricacies of gene function and the health of the planet. Because of this, scientists have long sought ways to eavesdrop on conversations between living microbes in their environment.
This has been exceptionally difficult, in part because microbes communicate using molecules instead of words. Deciphering conversations means identifying small, specific, and quickly changing molecules called metabolites, something even the most powerful instruments struggle to attempt. But a team of researchers at Pacific Northwest National Laboratory (PNNL) have spent the last decade continuously developing a next-generation bioimaging instrument that is making progress toward this goal.
The Chemical Dynamics Initiative (CDi), an internal PNNL investment, supported PNNL chemist Patrick El Khoury and his team as they developed the technology to measure phenomena in the quantum realm. Here the team imaged subatomic waves of energy called phonons as they formed, beat, and dissipated in a single trillionth of a second.
“Similar technologies can be used to image phonons and metabolites in real space and real time,” said El Khoury. “The fundamental advances required in both areas comprise a challenge worthy of a national laboratory and continued investments.”
Now researchers are taking the technologies to the next level as they use bioimaging to map metabolites exchanged by live microbes.
Bioimaging to fish out whispers in a crowd
The bioimager is known as BIGTUNA, short for BioImaginG Technology Using Nano-optical Approach. The keys to BIGTUNA are its multiple optical capabilities, each providing complementary information about the position and composition of molecules in a study sample. Many laser sources focus on the tip of a very sharp nanosized needle. Researchers position the needle’s tip in the sample area they want to examine, then use the light focused on the tip of the needle to measure the sample’s physical and chemical features. Through this, researchers identify molecules and understand how they interact.
One of the custom-built nano-optical system precursors to the BIGTUNA bioimaging device. Credit: Patrick El-Khoury, Pacific Northwest National Laboratory
Chemical bioimaging with light has been done for a hundred years, but never at this molecular scale.
“Some methods illuminate a relatively large area, but these far-field approaches are like listening in to a crowd and expecting to understand individual conversations,” said PNNL chemist Scott Lea. To overcome this challenge, researchers focused on combining a wide range of near-field techniques to capture and characterize the maximum information in an area as small as a few molecules.
“If we don’t have multiple streams of data coming from multiple techniques, we only get partial information,” said El Khoury. “And in addition to developing the techniques, we developed our understanding of optical selection rules to maximize the information we get from one sample in one set-up.”
In the most recent iteration of this project, the researchers zoomed out to a larger area, although still only a thousandth the thickness of a strand of hair. At this slightly farther distance, they identified the most promising approaches to capture information about the patterns of molecular bonds and the distribution of electrons. These new nano-optical measurements are addressing a much smaller number of molecules; therefore, the researchers must continue developing new theories that describe nanoscopic interactions of light and matter.
Combining these conceptual and technological developments will allow the researchers to move beyond model systems they studied using early incarnations of BIGTUNA. The chemical signals in these model systems were much stronger than chemical signals from the metabolites involved in microbial communications. In addition to having weaker signals, biological samples are also susceptible to damage by light, which is why BIGTUNA’s noninvasive approach makes it ideal to develop for bioimaging applications. Including state-of-the art data and computational techniques from PNNL data scientists Sarah Akers and Edo Aprà will help automate where and how the instrument balances exploration with the sensitivity of a living system.
Bioimaging to tune in to talking microbes
As an initial foray into biology, researchers are focusing BIGTUNA’s bioimaging power on a community of symbiotic microbes that live in deep ocean sediments. One microbe reduces sulfur, the other oxidizes methane, a powerful greenhouse gas.
Image of the microbe community (purple and green) within sediment particles (yellow) that researchers are studying through bioimaging with BIGTUNA. Credit: Patrick El Khoury, Pacific Northwest National Laboratory
Previous approaches to unraveling microbial interactions have mainly focused on identifying influential genes or on examining isolated enzymes and pathways. The approaches often include fixing, freezing, or combining the biological system. But these approaches lose out on time-dependent or space-specific details. And the researchers can’t look at the flow of metabolites to get a predictive understanding of how and why microbes interact.
Even so, PNNL collaborator and CalTech geologist Victoria Orphan has theories about how these symbiotic microbes share metabolites. Bioimaging with BIGTUNA could produce the first close-up view of the metabolites in action as the instrument sends light through the sample and measures what gets absorbed or scattered. Researchers use the information to identify metabolites and create a detailed record of microbial intercellular communication pathways. In turn, this knowledge could help researchers understand the degree to which microbes respond to environmental changes.
A new generation of nano-optics
“Possibilities for BIGTUNA extend far beyond the realm of bioimaging,” said Peter Sushko, CDi’s chief scientist. “Because this highly adaptable instrument can obtain detailed information describing atomic motion and electronic processes, it will be useful in seeking answers to a broad range of questions that are of interest to chemists, physicists, and materials scientists as well.”
Potential applications include quantum materials, catalysis, and human health, in addition to the current work in microbial systems. In that realm, planned future developments could incorporate environmental controls to further generalize the approach.
A portion of the blueprint for BIGTUNA was designed under PNNL’s CDi, a five-year internal investment in capabilities to better understand and predict the evolution of complex chemical systems in real-world or operational environments.
The graphic illustrates five different effects of Ir-based catalysts, which were studied for future improvements for usage in proton exchange membrane water electrolyzers (PEMWEs). Credit: Nano Research Energy, Tsinghua University Press
Hydrogen production powered by wind and solar energy is still too expensive if it is to play a role in the clean transition via energy storage and to help decarbonize hard-to-electrify sectors. Much effort in reducing its cost focuses on enhancing production efficiency by improving the performance of iridium-based catalysts that can speed up the oxygen-related part of the electrochemical reaction involved in splitting water into its component parts, hydrogen and oxygen.
A new review of the state of the field discusses its recent progress and challenges and identifies research gaps that need to be filled before such catalysts can achieve commercial viability.
The review paper was published in the journal Nano Research Energy.
Cleanly produced hydrogen is essential in the transition away from fossil fuels in order to avoid dangerous climate change, both as an energy carrier to be used on its own or as a component of a synthetic fuel for those sections of the economy such as long-haul shipping and aviation that are hard to electrify.
But such clean hydrogen production—which is performed via electrolysis, using electricity to split water into its component elements, hydrogen and oxygen—is extremely energy intensive. This energy intensity of electrolysis in turn makes clean production of hydrogen very expensive, and thus uncompetitive with fossil fuels.
If this were not enough of a challenge, using wind and solar energy as the source of clean electricity to power the electrolysis—a form of hydrogen production termed ‘green hydrogen’—places a significant burden on the electrolyzers because these energy sources are intermittent. The sun doesn’t always shine and the wind doesn’t always blow.
This means that sometimes there is little to no current and at other times, there can be a big spike of current, which places stress on the electrolyzers, again pushing up costs. However, proton exchange membrane water electrolyzers (PEMWE) are a very promising option here, as PEMWEs can operate at high current densities such as those posed by these spikes.
Electrolysis is a chemical reaction composed of two parts, or ‘half reactions.’ One is the hydrogen evolution reaction (HER), which generates the hydrogen, and the other is the oxygen evolution reaction (OER), which produces the oxygen. But it is actually the latter reaction that is most important with respect to the energy efficiency of the overall process and thus production of clean hydrogen.
And so to reduce the energy demands and thus the cost of clean production of hydrogen, a lot of research has focused on superior catalysts—chemicals that speed up a chemical reaction—for the OER part of the process and that pair well with PEMWEs.
However, the severe corrosion in the acidic environment of PEMWEs makes most non-precious metal-based catalysts—for example using cobalt, nickel, or iron—unstable. But iridium-based catalysts exhibit much better catalytic stability in these harsh acidic conditions.
A number of recent studies have reported significant advances in the development of iridium-based catalysts for green hydrogen production, including the use of new synthesis methods and the optimization of catalyst structures and compositions.
However, there are still several research challenges that need to be addressed to fully realize the potential of iridium-based catalysts for green hydrogen production. One major challenge is the high cost of iridium—and high costs are precisely what novel catalysts were intended to avoid.
“To overcome this, researchers are exploring new synthesis methods and alternative catalyst materials that can replace iridium or reduce the amount of iridium required,” said Chunyun Wang, of the School of Chemistry and Chemical Engineering at Yangzhou University and lead author of the review. “Some novel and effective options have emerged recently, such as iridium oxides, perovskites, pyrochlores, and single-atom catalysts.”
“And so we thought it was about time that we paused and assessed the state of play in iridium-based catalysts for green hydrogen production with a review paper,” added Alex Schechter, a chemist with Ariel University in Israel and co-author of the review paper. “The benefit of this is to pool information across many different teams of researchers and, crucially, identify research gaps.”
The review focuses in particular on how the catalysis operates (the catalytic mechanism), design of catalysts, and strategies for synthesis of catalysts. In particular, the analysis looks at different attributes of catalysts that affect their promotion of the catalysis process including geometric effects, electronic effects, synergistic effects, defect engineering and support effects, and how different research teams have dealt with each option to try to improve performance.
Geometric effects in essence describe the shape, structure and size of the catalyst molecule, including which of its crystal planes are exposed, and how atomic arrangements might be ordered or disordered. All of this significantly affects catalyst performance. Electronic effects refer to the structure of electrons associated with the relevant molecules.
Synergistic effects are those where two or more ingredients come together to produce a superior result than either one on its own. Defect engineering involves efforts to design the surface chemistry of catalysts via voids, dislocations, vacancies and so on—deliberately introducing imperfections—so as to increase the number of places where the chemical reaction can take place (active sites). And support effects come from metals that interact with and support the catalyst.
The reviewers concluded after surveying their field that the most successful strategy for improving the performance of iridium-based catalysts includes defect engineering, adjusting synergistic effects and altering geometric effects. The number of exposed active sites can be increased by constructing a porous structure and introducing supports for the catalyst that promote transfer of both mass and electrons. And enhanced metal-support interaction can increase the long-term stability of the catalysts.
Despite the considerable research success, the field still faces challenges. Many high-performance iridium-based catalysts have been developed, but most of them can only be synthesized on a small scale of just a few grams or even hundreds of milligrams in the laboratory. Complex preparation processes thus must be simplified.
In addition, lab conditions are a bit too ideal compared to actual catalytic systems, and so real-world conditions need to be part of any follow-up research. This includes looking at realistic electrolyzer temperature, current density, and product delivery, amongst other aspects, that will enable evaluation of performance catalysts in practical applications.
And beyond the catalysts themselves, other components need to be optimized as well, including the development of electrode plates with high corrosion resistance and low cost, proton exchange membranes with high proton transport capacity.
The reviewers stressed however that none of these challenges are deal-breakers for iridium-based catalysts for green hydrogen production. Instead these represent possible avenues for new research that may deliver the breakthroughs this process requires to achieve commercial viability.
More information: Chunyan Wang et al, Iridium-based catalysts for oxygen evolution reaction in acidic media: Mechanism, catalytic promotion effects and recent progress, Nano Research Energy (2023). DOI: 10.26599/NRE.2023.9120056
A model shows how glycine molecules (teal) interact with brain cell receptors called GPR158 to influence the nervous system. The dotted lines show hydrogen bonds and weak electrical field attractions that start the signal. Credit: Martemyanov lab at The Wertheim UF Scripps Institute.
A common amino acid, glycine, can deliver a “slow-down” signal to the brain, likely contributing to major depression, anxiety and other mood disorders in some people, scientists at the Wertheim UF Scripps Institute for Biomedical Innovation & Technology have found.
The discovery, outlined Thursday in the journal Science, improves understanding of the biological causes of major depression and could accelerate efforts to develop new, faster-acting medications for such hard-to-treat mood disorders, said neuroscientist Kirill Martemyanov, Ph.D., corresponding author of the study.
“Most medications for people with depression take weeks before they kick in, if they do at all. New and better options are really needed,” said Martemyanov, who chairs the neuroscience department at the institute in Jupiter.
Major depression is among the world’s most urgent health needs. Its numbers have surged in recent years, especially among young adults. As depression’s disability, suicide numbers and medical expenses have climbed, a study by the U.S. Centers for Disease Control and Prevention in 2021 put its economic burden at $326 billion annually in the United States.
Martemyanov said he and his team of students and postdoctoral researchers have spent many years working toward this discovery. They didn’t set out to find a cause, much less a possible treatment route for depression. Instead, they asked a basic question: How do sensors on brain cells receive and transmit signals into the cells? Therein lay the key to understanding vision, pain, memory, behavior and possibly much more, Martemyanov suspected.
“It’s amazing how basic science goes. Fifteen years ago we discovered a binding partner for proteins we were interested in, which led us to this new receptor,” Martemyanov said. “We’ve been unspooling this for all this time.”
In 2018 the Martemyanov team found the new receptor was involved in stress-induced depression. If mice lacked the gene for the receptor, called GPR158, they proved surprisingly resilient to chronic stress.
That offered strong evidence that GPR158 could be therapeutic target, he said. But what sent the signal?
A breakthrough came in 2021, when his team solved the structure of GPR158. What they saw surprised them. The GPR158 receptor looked like a microscopic clamp with a compartment—akin to something they had seen in bacteria, not human cells.
“We were barking up the completely wrong tree before we saw the structure,” Martemyanov said. “We said, ‘Wow, that’s an amino acid receptor. There are only 20, so we screened them right away and only one fit perfectly. That was it. It was glycine.”
That wasn’t the only odd thing. The signaling molecule was not an activator in the cells, but an inhibitor. The business end of GPR158 connected to a partnering molecule that hit the brakes rather than the accelerator when bound to glycine.
“Usually receptors like GPR158, known as G protein Coupled Receptors, bind G proteins. This receptor was binding an RGS protein, which is a protein that has the opposite effect of activation,” said Thibaut Laboute, Ph.D., a postdoctoral researcher from Martemyanov’s group and first author of the study.
Scientists have been cataloging the role of cell receptors and their signaling partners for decades. Those that still don’t have known signalers, such as GPR158, have been dubbed “orphan receptors.”
The finding means that GPR158 is no longer an orphan receptor, Laboute said. Instead, the team renamed it mGlyR, short for “metabotropic glycine receptor.”
“An orphan receptor is a challenge. You want to figure out how it works,” Laboute said. “What makes me really excited about this discovery is that it may be important for people’s lives. That’s what gets me up in the morning.”
Laboute and Martemyanov are listed as inventors on a patent application describing methods to study GPR158 activity. Martemyanov is a cofounder of Blueshield Therapeutics, a startup company pursuing GPR158 as a drug target.
Glycine itself is sold as a nutritional supplement billed as improving mood. It is a basic building block of proteins and affects many different cell types, sometimes in complex ways. In some cells, it sends slow-down signals, while in other cell types, it sends excitatory signals. Some studies have linked glycine to the growth of invasive prostate cancer.
More research is needed to understand how the body maintains the right balance of mGlyR receptors and how brain cell activity is affected, he said. He intends to keep at it.
“We are in desperate need of new depression treatments,” Martemyanov said. “If we can target this with something specific, it makes sense that it could help. We are working on it now.”
Free at last—This collection of microscope photos depicts the wonderful moments of dynamic particles moving towards various freestanding membranes at the air-liquid interface. Credit: National University of Singapore
A breakthrough in synthesis strategy enables the facile formulation of inorganic membranes that are not just energy-efficient but also highly customizable, potentially revolutionizing the way many industries operate for greater sustainability.
Inorganic membranes can be thought of as kitchen sieves. Similar to how sieves separate smaller particles from larger ones, inorganic membranes, typically made of ceramics or metals, selectively separate molecules based on their size and properties.
In a ground-breaking achievement, a team of researchers from the College of Design and Engineering (CDE) at the National University of Singapore, led by Professor Ho Ghim Wei from the Department of Electrical and Computer Engineering, has developed a revolutionary technique for producing ultrathin inorganic membranes. These freestanding membranes can function without any supporting substrate—a significant advancement in membrane technology. The team’s findings were published in the scientific journal Nature on March 29, 2023.
Highly customizable and simple to produce, the inorganic membranes—underpinned by a universal, facile synthesis strategy—have the potential to benefit applications beyond filtration and separation. From energy conversion to catalysis and sensing, the membranes’ versatility could transform various sectors and industries that depend on membrane technology. By promoting efficiency and sustainability in industrial processes, the NUS scientists’ pioneering research has unveiled new possibilities for overcoming energy challenges in the face of climate change.
Membranes reimagined
Conventional membrane technologies used in purification and separation processes are known to be energy-intensive and therefore expensive, often entailing a combination of pressure, heat, and sometimes chemicals to function effectively. Moreover, the membranes must be regenerated, while the filtered components usually require further treatment after separation, leading to additional energy demands and costs.
Such limitations of traditional membrane technologies served as the impetus for postdoctoral research fellow Dr. Zhang Chen in Prof Ho’s team to develop a new synthesis strategy for highly efficient inorganic membranes. Dr. Zhang’s method involves taming chaotic, free-floating, inorganic building-blocks in a liquid environment, coaxing them to self-assemble into the desired membrane. This tunable process provides an effective means to tailor the membrane’s thickness and pore characteristics for specific applications, achieving maximum energy efficiency.
“Our study has also allowed us to take a fresh approach to rethink how inorganic membranes are traditionally developed,” added Dr. Zhang.
The NUS scientists have presented a synthesis template that other researchers can utilize for their work, which could spur the discovery of more novel membranes with a wider compositional range in a scalable and cost-effective manner.
From a structural perspective, the membranes they produced have more geometric diversity than conventional ones, providing more flexibility and options when designing membrane structures.
Additionally, the study also explores membrane functionality, where highly selective 2D barriers are used to control energy flow across the membrane. This feature could influence how the membrane functions—allowing ions to be filtered based on their charge, different forms of energy such as thermal, electrical, or light to be harnessed, or specific molecules to be selectively concentrated. Such flexibility is highly desirable in various energy-related applications, including fuel cells and solar energy conversion.
“Our new technique has the potential to transform industries that heavily rely on membranes for their operation, particularly those related to energy or the environment,” said Prof Ho. “The ability to create freestanding inorganic membranes that are highly selective opens up numerous exciting possibilities for applications in advanced spatial dynamic separation, catalysis, sensors, memories, and ionic conductors, all of which represent unprecedented developments.”
Formulating a greener future
With an emphasis on efficiency and customization, the researchers’ innovation plays a key role in NUS’ sustainability initiatives, greatly reducing the energy consumption of membrane-related processes worldwide and cutting the carbon footprint of various industries as a result.
Driven by the potential of the breakthrough, Prof Ho plans to lead an interdisciplinary team of scientists in a multi-faceted research program to advance membrane technology to the next level. “By exploring the vast range of membrane compositions and coupling them with various forms of energy, we hope to unlock new applications and make further strides towards a more sustainable future,” shared Prof Ho.
The team is also looking to develop automated manufacturing tools to streamline the production process of inorganic membranes, ultimately making their technology more accessible on a larger scale.
More information: Chen Zhang et al, Mechanistic formulation of inorganic membranes at the air–liquid interface, Nature (2023). DOI: 10.1038/s41586-023-05809-y
Photocatalysis is the use of light to accelerate the rate of a reaction in the presence of a photocatalyst. The catalyst plays a crucial role in this process—it absorbs the light being shined onto it and makes it available in ways that can help accelerate the chemical reaction and also enhance it. These catalysts are used for a variety of light-dependent reactions ranging from the production of paper to the conversion of carbon dioxide to fuel.
Given these applications, the development of ideal photocatalysts is important. An ideal photocatalyst is one that uses a single transition metal that performs both visible light absorption and chemical transformation. Currently, visible light-driven single transition metal catalysts are limited to only one mechanism of operation, known as the radical mechanism, or have a low light-harvesting ability, making them heavily dependent on certain substrates. Thus, there is a need for an ideal single transition metal catalyst that solves these problems.
A team of researchers from Tokyo Institute of Technology (Tokyo Tech), led by Assistant Professor Yuki Nagashima, have reported a novel visible light-driven single transition metal catalyst that solves these issues. Their findings are published in Nature Synthesis. Dr. Nagashima explains, “We envisioned unprecedented rhodium (Rh)-based photocatalysts—spiro-fluorene-indenoindenyl (SFI)-Rh(I) complexes—that combine high light harvesting abilities with broad applicability.”
The team found that extending the molecules around the central Rh atom—called the ligand—is necessary to increase the light harvesting abilities of these complexes, but also makes them less stable. Thus, the team designed SFI-Rh(I) complexes using a non-fused extension strategy, extending the molecules around the ligand without compromising the stability of the resultant catalyst.
In fact, their extension strategy made the catalyst stable against protonation and helped in increasing its light-harvesting ability, thus reducing its substrate dependence. The catalyst was also designed to be able to perform using multiple mechanisms, beyond the radical mechanism used by previous catalysts.
“The careful design of our catalyst enabled it to have many advantages compared to previously described catalysts, while making it suitable for complex reactions. The SFI-Rh(I) complexes can easily extend the scope of typical Rh-catalyzed reactions using blue light LED irradiation at room temperature. This opens many avenues for future applications of these catalysts, as well as photocatalytic reactions in general,” says Nagashima.
“We believe that this catalyst has the potential to be a versatile light-driven catalyst that can break through the ground-state limitations in various photoreactions.”
Using energy from light equivalent to sunlight the artificial photosynthesis system uses enzymes and a rhodium catalyst to produce a biodegradable plastic precursor. Now for the first time, the process works using low concentrations of CO2, similar to exhaust gas, and waste acetone as raw materials. Credit: Yutaka Amao, OMU
Osaka Metropolitan University scientists have developed a process using artificial photosynthesis to successfully convert more than 60% of waste acetone into 3-hydroxybutyrate, a material used to manufacture biodegradable plastic. The results were obtained using low-concentration CO2, equivalent to exhaust gas, and powered by light equivalent to sunlight for 24 hours.
The researchers expect that this innovative way of producing biodegradable plastic could not only reduce CO2 emissions but also provide a way of reusing laboratory and industrial waste acetone. Their findings have been published in the journal Green Chemistry.
Poly-3-hydroxybutyrate—a biodegradable plastic—is a strong water-resistant polyester often used in packaging materials, made from 3-hydroxybutyrate as a precursor. In previous studies, a research team led by Professor Yutaka Amao from the Research Center for Artificial Photosynthesis at Osaka Metropolitan University found that 3-hydroxybutyrate can be synthesized from CO2 and acetone with high efficiency, but this was only demonstrated at higher concentrations of CO2 or sodium bicarbonate.
This new study aimed to reuse waste acetone from permanent marker ink and low concentrations of CO2—equivalent to exhaust gas from power plants, chemical plants, or steel factories. Acetone is a relatively inexpensive and reasonably harmless chemical used in many different laboratory settings, either for reactions or as a cleaning agent, which produces waste acetone. The acetone and CO2 acted as raw materials to synthesize 3-hydroxybutyrate using artificial photosynthesis, powered by light equivalent to sunlight.
“We focused our attention on the importance of using CO2 created by exhaust gas from thermal power plants and other sources to demonstrate the practical application of artificial photosynthesis,” explained Professor Amao.
After 24 hours, more than 60% of acetone had been successfully converted to 3-hydroxybutyrate. “In the future, we aim to develop artificial photosynthesis technology further, so that it can use acetone from liquid waste and as well as exhaust gas from the laboratory as raw materials,” stated Professor Amao.
More information: Yu Kita et al, Visible-light-driven 3-hydroxybutyrate production from acetone and low concentrations of CO2 with a system of hybridized photocatalytic NADH regeneration and multi-biocatalysts, Green Chemistry (2023). DOI: 10.1039/D3GC00247K
