Category: Chemistry

Researchers have developed and demonstrated an efficient and scalable technique that allows them to manufacture soft polymer materials in a dozen different structures, or “morphologies,” from ribbons and nanoscale sheets to rods and branched particles. The technique allows users to finely tune the morphology of the materials at the micro- and nano-scale. The paper, “Fluid Flow Templating of Polymeric Soft Matter with Diverse Morphologies,” is published open access in the journal Advanced Materials.

“This advance is important because the technique can be used with a wide variety of polymers and biopolymers. Since the morphology of these polymeric micro- and nanostructures is critical for their applications, it allows us to obtain new polymer functionalities by simply controlling structure instead of polymer chemistry,” says Orlin Velev, corresponding author of the paper and the S. Frank and Doris Culberson Distinguished Professor of Chemical and Biomolecular Engineering at North Carolina State University.

“For example, the nanosheets can be used in designing better batteries, whereas dendricolloids—branching networks of polymer fibers that have exceptionally high surface area—can be used in environmental remediation technologies or creation of novel lightweight metamaterials.”

Fundamentally, all of the different morphologies are produced using a well-known process called polymer precipitation. In this process, a polymer is dissolved into a solvent, producing a polymer solution. That polymer solution is then introduced into a second liquid, which makes the polymer come back together as soft matter.

What’s new here is that the researchers have discovered how to precisely control the structure of the resulting polymer soft matter by manipulating three sets of parameters during the manufacturing process.

The first set of parameters is the shear rate, which refers to how quickly the liquids are stirred when the two liquids are mixed together. The second set of parameters is the concentration of the polymer in the polymer solution. The last set of parameters is the composition of the solvent that the polymer was initially dissolved in, as well as the composition of the liquid that the polymer solution is added to.

“We identified the critical parameters that affect the final morphology of the polymeric materials, which in turn gives us a great deal of control and versatility,” says Rachel Bang, first author of the paper and a recent Ph.D. graduate from NC State. “Because we now understand the role of each of these factors and how they all influence each other, we can reproducibly fine-tune the polymeric particle morphology.”

“Even though we have demonstrated how to produce a dozen different morphologies, we are still in the early stages of exploring all of the possible outcomes and applications,” Velev says.

The researchers have already demonstrated that the dendricolloids can be used to make membranes for growing live cells, or to create hydrophobic or hydrophilic coatings. The researchers have also worked with collaborators to demonstrate that the nanosheets have potential for use as more efficient separators in lithium-ion batteries.

“The technique can also be used with a variety of natural biopolymers, such as plant proteins, and it could be used to support a variety of applications, such as the development of plant-based meat analogs, which requires precise control of protein particle morphologies at multiple length scales,” adds co-author Prof. Simeon Stoyanov of the Singapore Institute of Technology and Wageningen University in the Netherlands. “In addition, because our technique is based on mixing liquids using conventional mixers, it can be easily scaled up for practical manufacturing.”

“We are currently working with food science researchers to determine how protein microrods could be used to control the texture of some food products,” Velev says. “And we are also working with collaborators to explore how our technique can be used to produce biopolymer-based materials for use in biodegradable soft electronics.

“We are open to working with additional collaborators to explore potential applications for the polymers and biopolymers across all of these morphologies.”

NC State has issued or pending patents on the shear fabrication of microrods, nanofibers, dendricolloids and their application in electrochemical energy sources.

More information: Rachel S. Bang et al, Fluid Flow Templating of Polymeric Soft Matter with Diverse Morphologies, Advanced Materials (2023). DOI: 10.1002/adma.202211438

Journal information: Advanced Materials 

Provided by North Carolina State University 

NPL, in collaboration with London Biofoundry and BiologIC Technologies Ltd, have released an analysis on existing and emerging DNA Synthesis technologies in Nature Reviews Chemistry, featuring the work on the front cover.

The study, which was initiated by DSTL, set out to understand the development trajectory of DNA Synthesis as a major industry drive for the UK economy over the next 10 years. The demand for synthetic DNA is growing exponentially. However, our ability to make, or write, DNA lags behind our ability to sequence, or read, it. The study reviewed existing and emerging DNA synthesis technologies developed to close this gene writing gap.

DNA or genes provide a universal tool to engineer and manipulate living systems. Recent progress in DNA synthesis has brought up limitless possibilities in a variety of industry sectors. Engineering biology, therapy and diagnostics, data storage, defense and nanotechnology are all set for unprecedented breakthroughs if DNA can be provided at scale and low cost.

As an example, DNA has already been used to write books, episodes of Netflix series, video games and is being applied to catalog the entire British Library. Just one gram of DNA is estimated to store over 17 Exabytes of information, whereas 5 Exabytes is all that is needed to store all the words spoken by mankind.

The review details DNA chemistry, cross-compares the efficacies of synthesis technologies, outlines pros and cons of commercialized techniques versus future optimisations, and discusses oversight, security, deskilling, automation, and standardization of DNA synthesis.

The review identified common trends and dependences in DNA synthesis technologies, as well as leading companies who develop innovative solutions to circumvent current limitations. With existing technologies, it is now possible to make large DNA molecules and many DNA molecules simultaneously on tiny microchips.

As DNA synthesis becomes affordable, there are many options available from industry, from customized DNA synthesis to benchtop DNA printers allowing non-expert users themselves to make DNA. However, much remains to be addressed before we can reach the ability to make full sized genes and genomes and thereby close the gene writing gap.

Max Ryadnov, NPL Fellow, said, “Among other challenges, the development of robust metrology and suitable standards are required to accelerate and safeguard the uptake of synthetic DNA by the end users. Of particular relevance this is for the UK’s National Engineering Biology program, designed to build on the UK’s capabilities to boost businesses and commercialisation of enabling technologies. NPL supports this endeavor by developing a toolbox of traceable reference materials, methods and standards, which will underpin further developments in the field.”

More information: Alex Hoose et al, DNA synthesis technologies to close the gene writing gap, Nature Reviews Chemistry (2023). DOI: 10.1038/s41570-022-00456-9

Provided by National Physical Laboratory 

Fluorescence is a fascinating natural phenomenon. It is based on the fact that certain materials can absorb light of a certain wavelength and then emit light of a different wavelength. Fluorescent materials play an important role in our everyday lives, for example in modern screens. Due to the high demand for applications, science is constantly striving to produce new and easily accessible molecules with high fluorescence efficiency. Chemist Professor Evamarie Hey-Hawkins from Leipzig University and her colleagues have specialized in a particular class of fluorescent materials—phospholes.

These consist of hydrocarbon frameworks with a central phosphorus atom. In experiments with this substance, Nils König from Hey-Hawkins’ working group has found access to new fluorescent materials. He has now published his findings in the journal Chemical Science.

“Phospholes can be modified by certain chemical reactions, which has a major impact on the color and efficiency of the fluorescence of the molecule. Another special feature of these substances is their propeller-like structure,” explains König. When these molecules are dissolved in a solvent and exposed to UV light, they do not fluoresce. The absorbed energy is released in the form of rotational motion, causing the molecules to spin like a propeller in the solvent. In a crystalline state, however, the ability to rotate is severely limited, which makes the substances fluoresce strongly under UV light. This behavior is known as aggregation-induced emission (AIE).

In the recently published paper, Nils König and his colleagues demonstrated a new reaction on AIE-based phospholes, which provided access to a new class of substances. Phospholes can be modified under mild conditions by isocyanates, a reactive class of substances consisting of the elements nitrogen, oxygen and carbon, which are inexpensive and widely available due to their industrial applications in the field of polymers and biochemistry. This reaction, which seems to contradict classical organic chemistry, is characterized by high yields and excellent atom economy.

The optical properties of the new substances were investigated in collaboration with the Institute of Surface Engineering (IOM) in Leipzig, as well as the Center for Nanotechnology (CeNTech) and the University of Münster (WWU). It turned out that the simple modification significantly increased the efficiency of fluorescence compared to the original substances. This is due to the formation of a unique interaction between parts of the molecular framework, which significantly strengthens the molecule in the solid state and leads to stronger fluorescence. The new modification method thus makes a major contribution to understanding the AIE concept and could serve as a tool for synthesizing efficient new dyes for screens or as markers for biomolecules.

More information: Nils König et al, Facile modification of phosphole-based aggregation-induced emission luminogens with sulfonyl isocyanates, Chemical Science (2023). DOI: 10.1039/D3SC00308F

Journal information: Chemical Science 

Provided by Leipzig University 

A team of Rutgers scientists dedicated to pinpointing the primordial origins of metabolism—a set of core chemical reactions that first powered life on Earth—has identified part of a protein that could provide scientists clues to detecting planets on the verge of producing life.

The research, published in Science Advances, has important implications in the search for extraterrestrial life because it gives researchers a new clue to look for, said Vikas Nanda, a researcher at the Center for Advanced Biotechnology and Medicine (CABM) at Rutgers.

Based on laboratory studies, Rutgers scientists say one of the most likely chemical candidates that kickstarted life was a simple peptide with two nickel atoms they are calling “Nickelback” not because it has anything to do with the Canadian rock band, but because its backbone nitrogen atoms bond two critical nickel atoms. A peptide is a constituent of a protein made up of a few elemental building blocks known as amino acids.

“Scientists believe that sometime between 3.5 and 3.8 billion years ago there was a tipping point, something that kickstarted the change from prebiotic chemistry—molecules before life—to living, biological systems,” Nanda said. “We believe the change was sparked by a few small precursor proteins that performed key steps in an ancient metabolic reaction. And we think we’ve found one of these ‘pioneer peptides.'”

The scientists conducting the study are part of a Rutgers-led team called Evolution of Nanomachines in Geospheres and Microbial Ancestors (ENIGMA), which is part of the Astrobiology program at NASA. The researchers are seeking to understand how proteins evolved to become the predominant catalyst of life on Earth.

When scouring the universe with telescopes and probes for signs of past, present or emerging life, NASA scientists look for specific “biosignatures” known to be harbingers of life. Peptides like nickelback could become the latest biosignature employed by NASA to detect planets on the verge of producing life, Nanda said.

An original instigating chemical, the researchers reasoned, would need to be simple enough to be able to assemble spontaneously in a prebiotic soup. But it would have to be sufficiently chemically active to possess the potential to take energy from the environment to drive a biochemical process.

To do so, the researchers adopted a “reductionist” approach: They started by examining existing contemporary proteins known to be associated with metabolic processes. Knowing the proteins were too complex to have emerged early on, they pared them down to their basic structure.

After sequences of experiments, researchers concluded the best candidate was Nickelback. The peptide is made of 13 amino acids and binds two nickel ions.

Nickel, they reasoned, was an abundant metal in early oceans. When bound to the peptide, the nickel atoms become potent catalysts, attracting additional protons and electrons and producing hydrogen gas. Hydrogen, the researchers reasoned, was also more abundant on early Earth and would have been a critical source of energy to power metabolism.

“This is important because, while there are many theories about the origins of life, there are very few actual laboratory tests of these ideas,” Nanda said. “This work shows that, not only are simple protein metabolic enzymes possible, but that they are very stable and very active—making them a plausible starting point for life.”

More information: Jennifer Timm et al, Design of a Minimal di-Nickel Hydrogenase Peptide, Science Advances (2023). DOI: 10.1126/sciadv.abq1990. www.science.org/doi/10.1126/sciadv.abq1990

Journal information: Science Advances 

Provided by Rutgers University 

A review article, published in Science China Chemistry and led by Prof. Fan Dong and associate research fellow Bangwei Deng (Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China), was written to inspire more investigations and studies on the intrinsic active sites during the dynamic evolution of catalysts that could promote the optimization of the catalyst system to further improve the performance of CO₂RR.

To date, copper-based catalysts are one of the most prominent catalysts that can electrochemically reduce CO₂ towards high value fuels or chemicals, such as ethylene, ethanol, acetic acid.

However, the chemically active feature of Cu-based catalysts hinders the understanding of the intrinsic catalytic active sites during the initial and the operative processes of CO₂RR. The identification and engineering of active sites during the dynamic evolution of catalysts are thereby vital to further improve the activity, selectivity, and durability of Cu-based catalysts for high-performance CO₂RR.

In this regard, four triggers for the dynamic evolution of catalysts were introduced in detail. Afterward, three typical active-site theories during the dynamic reconstruction of catalysts were discussed. In addition, the strategies in catalyst design were summarized according to the latest reports of Cu-based catalysts for CO₂RR, including the tuning of electronic structure, controlling of the external potential, and regulation of local catalytic environment.

“The dynamic reconstruction of catalysts has now been well accepted by the research community, especially for Cu-based catalysts. Even though great advances have been achieved in the research of high performance CO₂RR, however, the activity, selectivity, and durability for the industrial application of CO₂RR on Cu-based catalysts are still unsatisfactory, particularly in the production of C₂₊ products. The detailed mechanisms on the intrinsic active site behind these dynamic properties, which are very important for the advanced catalyst design, are still ambiguous and more investigations are needed in future studies,” Dong says.

Some perspectives are also given here to guide future studies: 1) The triggers of the dynamic evolution of Cu-based catalysts should be carefully investigated, since several factors (intermediates, electrolyte, applied potential) are present along during CO₂RR; 2) More factors such as such as the electrolytic cell type, mass/electron transfer, local electric field, pH variations, solution resistance, hydrophilic/hydrophobic feature of reaction interface, and supporting effects should be considered during the catalyst design; 3) High-throughput testing and machine learning are efficient techniques to further establish the structure–property relationship in more complicated conditions.

More information: Bangwei Deng et al, Active site identification and engineering during the dynamic evolution of copper-based catalysts for electrocatalytic CO2 reduction, Science China Chemistry (2022). DOI: 10.1007/s11426-022-1412-6

Provided by Science China Press 

In a study is published in Science China Chemistry and led by Prof. Yuqin Zou (College of Chemistry and Chemical Engineering, Hunan University), experiments were performed by using a series of in situ characterization and the density functional theory (DFT) calculation.

It is noteworthy that the experimental findings show that Cu⁰ catalyzed furfural hydrogenation without Cu⁺ possesses a slow hydrogenation rate and poor selectivity. In contrast, the Cu⁰-Cu⁺ active sites possess excellent performance in the selective hydrogenation of furfural to produce furfuryl alcohol.

Moreover, this catalytic advantage shows a clear potential dependence, with a regular decrease in furfural selective hydrogenation performance when a decrease in potential leads to a decrease in the proportion of Cu⁺.

“Cu-based catalysts have shown excellent catalytic performance for the electrochemical hydrogenation of furfural to produce furfuryl alcohol. However, the true reaction active site remains unclear. Mixed-valence Cu oxide catalysts demonstrate excellent furfuryl alcohol selectivity but are limited by the dynamic electrocatalyst surface during catalysis. In situ capture of the true reaction activity sites and thus insight into the origin of the cu-based catalyst furfural electrochemical hydrogenation activity is necessary. This work could inform the optimal design of all Cu based catalyst electrocatalytic hydrogenation processes for organics,” Zou says.

Herein, the oxidation state of the prepared CuO nanowire under the ECH of furfural was tracked by in situ X-ray absorption spectroscopy (XAS). The co-existence of Cu⁰ and Cu⁺ states during the electrohydrogenation was con-firmed. Moreover, the poisoning experiment proved the decisive role of Cu+ in the furfural ECH.

Finally, the reaction energy barriers of the furfural ECH on Cu(111), Cu₂O(111), and Cu⁰-Cu⁺ were analyzed by the density functional theory (DFT) calculation. It is concluded that Cu⁰-Cu⁺ active sites on the surface of CuO synergistically the conversion of furfural to furfuryl alcohol, and the respective roles of Cu⁰ and Cu⁺ have also been revealed: Cu⁺ accelerates the second-step hydrogenation process of furfural, and Cu0 reduces the energy barrier for desorption of furfuryl alcohol.

More information: Zhongcheng Xia et al, Promoting the electrochemical hydrogenation of furfural by synergistic Cu⁰−Cu⁺ active sites, Science China Chemistry (2022). DOI: 10.1007/s11426-022-1407-0

Provided by Science China Press 

A new type of catalyst breaks down polyolefin plastics into new, useful products. This project is part of a new strategy to reduce the amount of plastic waste and its impact on our environment, as well as recover value that is lost when plastics are thrown away. The catalyst was developed by a team from the Institute for Cooperative Upcycling of Plastic (iCOUP), a U.S. Department of Energy, Energy Frontier Research Center. The effort was led by Aaron Sadow, the director of iCOUP, scientist at Ames National Laboratory, and professor at Iowa State University; Andreas Heyden, professor at the University of South Carolina; and Wenyu Huang, scientist at Ames Lab and professor at Iowa State. The new catalyst is made only of earth-abundant materials, which they demonstrated can break carbon-carbon (CC) bonds in aliphatic hydrocarbons.

Aliphatic hydrocarbons are organic compounds made up of only hydrogen and carbon. Polyolefin plastics are aliphatic hydrocarbon materials composed of long chains of carbon atoms linked together to form strong materials. These materials are a big part of the plastic waste crisis. Wenyu Huang said, “More than half of produced plastics so far are polyolefin based.”

Polyolefin plastics are used everywhere in the modern world, including in shrink wrap and other packaging products, containers for liquids such as detergents or milk, fibers in waterproof clothing, dental floss, and electronics. Yet, as Andreas Heyden explained, polyolefins are some of the most difficult plastics to recycle and new approaches are needed. One such promising alternative to recycling is known as upcycling. This approach involves chemical transformation of the materials into higher value products.

One way to upcycle polyolefins is a chemical process called hydrogenolysis. During this process, a catalyst splits chains of molecules by cutting CC bonds and adding hydrogen. According to Aaron Sadow, catalysts that are used for hydrogenolysis are typically based on precious metals, such as platinum. Platinum is expensive because of its low abundance in the earth’s crust, and due to its effectiveness, it is used in many types of catalytic transformations.

To address both challenges of sustainability and economy, Heyden said, “We thought we’d be able to use earth-abundant elements to create much cheaper catalytic materials, and by assembling these elements in a certain way we might achieve a high selectivity and still very good activity.”

The team discovered that zirconia, an earth-abundant metal oxide, can cut CC bonds in aliphatic hydrocarbon polymers at about the same speed of precious metal catalysts. “We were surprised that we could do hydrogenolysis of CC bonds, using zirconium oxide as the catalyst. The conventional paradigm is that zirconia is not very reactive on its own,” said Sadow.

The key to its success is the structure of the catalyst, which was designed by Wenyu Huang and his group. “In this architecture, ultrasmall zirconia nanoparticles are embedded between two plates of mesoporous silica. The two silica plates are fused, with the zirconia embedded in the middle, like a sandwich,” Huang said. “The pores in the silica provide access to the zirconia, while the sandwich-like structure protects the zirconia nanoparticles from sintering or crystallization, which would make them less effective.”

Heyden’s team was in charge of modeling the reaction and understanding where and how the active site works under reaction conditions. “And so for that we do both quantum chemical modeling of the catalyst and the chemical reactions together with some classical chemical reactor modeling,” he explained. “And here we really saw the importance of that amorphous zirconia structure.”

According to Sadow, the idea to study zirconia in hydrogenolysis was based on previous pioneering research of polymer depolymerization using zirconium hydrides studied in the late 1990s. “Harnessing zirconium hydrides for hydrogenolysis is really nice chemistry,” he said. “The problem is those zirconium organometallic species are really air and water sensitive. So they have to be handled under the cleanest of conditions. Typically polymer waste is not pure and isn’t supplied as a clean and perfectly dry starting material. Using a zirconium hydride catalyst, you’d have to really worry about impurities that inhibit the chemistry.”

The new zirconia material the team developed is simply heated under vacuum before the reactions, and it stays active during the hydrogenolysis process. “Zirconium oxide is easily handled in air and then activated. It doesn’t require any kind of really specialized conditions, which was also exciting,” Sadow said. “Being able to take an air-exposed metal oxide, heat it with an alkane, and generate an organometallic is a really powerful reaction that enables this kind of hydrogenolysis process. It potentially could enable lots of interesting catalytic transformations of hydrocarbons that were previously not considered.”

This research is further discussed in the paper “Ultrasmall amorphous zirconia nanoparticles catalyse polyolefin hydrogenolysis,” written by Shaojiang Chen, Akalanka Tennakoon, Kyung-Eun You, Alexander L. Paterson, Ryan Yappert, Selim Alayoglu, Lingzhe Fang, Xun Wu, Tommy Yunpu Zhao, Michelle P. Lapak, Mukunth Saravanan, Ryan A. Hackler, Yi-Yu Wang, Long Qi, Massimiliano Delferro, Tao Li, Byeongdu Lee, Baron Peters, Kenneth R. Poeppelmeier, Salai C. Ammal, Clifford R. Bowers, Frédéric A. Perras, Andreas Heyden, Aaron D. Sadow, and Wenyu Huang, and published in the Nature Catalysis.

More information: Shaojiang Chen et al, Ultrasmall amorphous zirconia nanoparticles catalyse polyolefin hydrogenolysis, Nature Catalysis (2023). DOI: 10.1038/s41929-023-00910-x

Journal information: Nature Catalysis 

Provided by Ames Laboratory 

Snakes bite 5.4 million people each year—and roughly half are injected with venom, according to the WHO. Between 81,000 and 138,000 people die, while around three times as many suffer amputations and other permanent disabilities. Due to their size, children often suffer the most severe effects.

For 128 years, our primary treatment against snakebite has been using mixtures of polyclonal antibodies derived from immunized animal blood. Although they are proven effective, these medicines may cause adverse reactions that can sometimes be severe. So, the search for novel ways to treat severe snakebite envenoming is ongoing.

Recently, an international team of scientists led by DTU reached remarkable results and developed a new modernized prototype treatment that proves effective against the venom of African and Asian elapid snakes, such as some cobra, mamba, and krait species—many of which are among the world’s deadliest.

“We have previously developed antibodies against the venom toxins from single snake species; however, our new results demonstrate that our technology has great potential in neutralizing toxins from multiple species, even from different continents. This broadened cross-neutralization capacity is very promising. It could provide the basis for more effective treatments for snakebite victims in the future,” says Andreas Hougaard Laustsen-Kiel, a professor at DTU Bioengineering.

He conducted the research with colleagues at DTU, ETH Zurich, Universidad de Costa Rica, and industrial partners Sophion Bioscience and IONTAS. Their work is published in Nature Communications.

New antibody works against several neurotoxins

In essence, their approach is to develop antibodies of fully human origin, which offer fewer adverse reactions, competitive costs, and, when fine-tuned, superior efficacy. They use phage display technology, a popular in vitro methodology within drug discovery, to select antibodies that bind well to the toxins in the venom, enabling broad neutralization.

“There has been a revolution in recombinant antibody technology over the last three decades. I am delighted to be involved in these efforts to direct phage display technology to the blight of snakebite envenomation,” says John McCafferty, the inventor of antibody phage display. He founded IONTAS and has recently established a new anti-venom group at the University of Cambridge.

Deliberately selecting hundreds of antibody candidates and testing the most promising against toxins in different snake venoms, the researchers found that one in particular (2554_01_D11) was especially potent and broadly neutralizing. It bound to various neurotoxins present in the venoms of the monocled cobra, the forest cobra, the spectacled cobra, the king cobra, the black mamba, and the many-banded krait.

Subsequent in vivo studies showed that the antibody prevented or delayed death from venom. For the monocled cobra specifically, the antibody completely prevented lethality in envenomed mice.

“In light of the positive results regarding the neutralization of venom from the monocled cobra, we mimicked a true rescue situation, injecting mice with cobra venom and then administering the antibody. And sure enough, we were able to prevent death when the antibody was injected rapidly after envenoming,” says José María Gutiérrez, emeritus professor of Instituto Clodomiro Picado, University of Costa Rica.

While the antibody could not prevent death from black mamba venom, survival was prolonged by several hours, suggesting that the antibody provided a partial neutralization of the venom.

“These are remarkable results,” says Andreas Hougaard Laustsen-Kiel:

“The antibody we used worked against different neurotoxins derived from different snake species from different parts of the world. These toxins are far from identical but share some crucial similarities in their structure. And apparently, these are just enough for our antibody to display extensive cross-reactivity. We have yet to establish the boundaries of what this antibody can neutralize. Still, we would like to see if it shows the same promise concerning neurotoxins from, for example, the blue krait, the banded krait, and the Egyptian cobra.”

The researchers expect antibodies, such as 2554_01_D11, will be helpful when designing future envenoming therapies. At the same time, however, they stress that their pipeline for discovery could be useful in developing other broadly neutralizing antibodies against toxins from other animals, bacteria, viruses, and parasites or even in developing cancer therapies.

More information: Line Ledsgaard et al, Discovery and optimization of a broadly-neutralizing human monoclonal antibody against long-chain α-neurotoxins from snakes, Nature Communications (2023). DOI: 10.1038/s41467-023-36393-4

Journal information: Nature Communications 

Provided by Technical University of Denmark 

An air filter made out of corn protein instead of petroleum products can concurrently capture small particulates as well as toxic chemicals like formaldehyde that current air filters can’t.

The research could lead to better air purifiers, particularly in regions of the world that suffer from very poor air quality. Washington State University engineers report on the design and tests of materials for this bio-based filter in the journal Separation and Purification Technology.

“Particulate matter is not that challenging to filter but to simultaneously capture various kinds of chemical gas molecules, that’s more significant,” said Katie Zhong, professor in WSU’s School of Mechanical and Materials Engineering and a corresponding author on the paper. “These protein-based air filtering materials should be very promising to capture multiple species of air pollutants.”

Poor air quality is a factor in diseases such as asthma, heart disease and lung cancer. Commercial air purifiers remove tiny particles in soot, smoke or car exhaust, which could be inhaled directly into the lungs, but air pollution also often contains other hazardous gaseous molecules, such as carbon monoxide, formaldehyde and other volatile organic compounds.

With micron-sized pores, typical high efficiency particulate air filters, also known as HEPA filters, can capture the small particles but aren’t able to capture gaseous molecules. They are most often made of petroleum products and glass, which leads to secondary pollution when old filters are thrown away, Zhong said.

The WSU researchers developed a more environmentally friendly air filter made from corn protein fibers that was able to simultaneously capture 99.5% of small particulate matter, similar to commercial HEPA filters, and 87% of formaldehyde, which is higher than specially designed air filters for those types of toxics.

The researchers chose corn to study because of its abundance as an agricultural product in the U.S. The corn protein is also hydrophobic, which means that the protein repels water and could work well in a moist environment such as in a mask.

The amino acids in the corn protein are known as functional groups. When exposed at the protein’s surface, these functional groups act like multiple hands, grabbing the toxic chemical molecules. The researchers demonstrated this by exposing a functional group at the protein surface, where it grabbed formaldehyde. They theorize that further rearrangement of the proteins could develop a tentacle-like set of functional groups that could grab a variety of chemicals from the air.

“From the mechanism, it’s very reasonable to expect that this protein-based air filter could capture more species of toxic chemical molecules,” Zhong said.

The three-dimensional structure that they developed also offers more promise for a simple manufacturing method than thin films of proteins that the research team developed previously. They used a small amount of a chemical, polyvinyl alcohol, to glue the nanofibers together into a lightweight foam-like material.

“This work provides a new route to fabricating environmentally friendly and multi-functional air filters made from abundant natural biomass,” Zhong said. “I believe this technology is very important for people’s health and our environment, and it should be commercialized.”

The researchers would like to do more testing, including using a variety of functional group structures and other toxic chemical molecules. In addition to Zhong, the work was conducted by graduate student Shengnan Lin, Ming Luo, Flaherty assistant professor in the WSU School of Mechanical and Materials Engineering, and post-doctoral fellow Xuewei Fu.

More information: Shengnan Lin et al, A protein aerogel with distinctive filtration capabilities for formaldehyde and particulate pollutants, Separation and Purification Technology (2023). DOI: 10.1016/j.seppur.2023.123179

Provided by Washington State University 

Huge amounts of technical or Kraft lignin are formed during pulp production. This lignin is difficult to process and so is usually just incinerated for heat production. A team of researchers, reporting in the journal Angewandte Chemie, have now succeeded in developing a green method for recovering the flavoring agent vanillin from this raw material. The materials used in this method are all recycled from papermaking processes, and only power and heat need to be added.

Lignin and cellulose are essential components of wood. The molecular structure of lignin contains the structure of vanillin, the main flavoring substance from the vanilla plant, meaning that vanillin can be produced from lignin, although the process is laborious. At present, lignosulfonate, a substance also formed in some papermaking methods, is used for the industrial production of vanillin.

In order to make paper from wood fibers, all lignin has to be removed, otherwise the paper will take on the brown color of the lignin. However, the waste product in the most commonly used pulping method for industrial papermaking, the Kraft method, is not lignosulfonate but rather a technical lignin referred to as Kraft lignin. Kraft lignin is much harder to oxidize and depolymerize than other lignins and so at present cannot be used as a raw material. Instead, it is simply burnt as fuel for papermaking processes.

Siegfried Waldvogel and a team of researchers at the University of Mainz, Germany, have now discovered a method for producing vanillin from Kraft lignin. They say the method is environmentally friendly as it does not use any harmful chemicals, and it is convenient as it uses the raw materials present in pulp production. A key step in this new method is the production of the oxidizer by electrolysis of sodium carbonate.

“The idea started many years ago when playing around with innovative electrode materials that make it possible to take simple carbonates and make an oxidizer from them,” explains Waldvogel. One of these electrode materials was boron-doped diamond, and the researchers observed that, when carrying out electrolysis using this electrode material, the sodium carbonate was readily oxidized to peroxodicarbonate. The team then found out that this oxidizer was strong enough to degrade stubborn Kraft lignin.

The team report that, when freshly produced, the peroxodicarbonate depolymerizes and oxidizes Kraft lignin with similar effectiveness to traditional methods. However, in a departure from these conventional methods, no environmentally harmful chemicals are used or produced in the process.

The need for vanillin is high: “Most people only know of it from vanilla flavoring, but it is present in most chocolates and perfumes as well,” explains Waldvogel. Vanillin is also a precursor material for pharmaceuticals. All these uses mean that around twenty thousand tons of vanillin are needed every year, and the vanilla plant alone cannot keep up with this demand.

Until now it wasn’t possible to utilize Kraft lignin to meet demand, but the first steps are being made. Waldvogel and the team are already working on a pilot plant to test scaling up.

More information: Michael Zirbes et al, Peroxodicarbonate as a Green Oxidizer for the Selective Degradation of Kraft Lignin into Vanillin, Angewandte Chemie International Edition (2023). DOI: 10.1002/anie.202219217

Journal information: Angewandte Chemie International Edition  , Angewandte Chemie 

Provided by Wiley