Category: Chemistry

by FAPESP

Polyalthic acid from copaiba oil is an effective antibacterial and should be used to develop alternative medications that can contribute to the effort to overcome antimicrobial resistance (“superbugs”), according to an article by researchers based in Brazil and the United States published in the journal Antibiotics.

More than 2.8 million antibiotic-resistant infections occur in the US and more than 35,000 people die as a result each year, says a report issued in 2019 by the Centers for Disease Control and Prevention (CDC).

Antimicrobial or antibiotic resistance is when germs (bacteria, fungi) develop the ability to defeat the antibiotics designed to kill them (it does not mean our bodies are resistant to antibiotics). It is expected to become the main global cause of death by 2050.

The crisis is due to improper prescribing of antibiotics, intense use of these drugs in agriculture, and overuse of a small number since the leading pharmaceutical companies decided to abandon the development of antibiotics owing to high cost and low return on investment.

In this context, resorting to plants as a source of novel drugs has proved a promising alternative.

To stimulate knowledge production in this field, researchers in Brazil at the University of São Paulo’s Ribeirão Preto School of Pharmaceutical Sciences (FCFRP-USP) and São Carlos Institute of Physics (IFSC-USP), in collaboration with colleagues at the University of Franca (UNIFRAN), also in Brazil, and the College of Pharmacy and Health Sciences at Western New England University (WNE) in the US, investigated copaiba oil, derived from Copaifera trees and traditionally used in the Amazon region as a natural remedy for its wound-healing, anti-inflammatory and antimicrobial properties. Its main constituents are diterpenes (20%), including polyalthic acid, and sesquiterpenes (80%). Both groups of compounds are anti-inflammatory and antimicrobial.

The researchers synthesized four polyalthic acid analogs with structural modifications to make them more active against pathogens, and investigated their efficacy against biofilms of Staphylococcus epidermidis, a bacterium that causes skin and digestive tract infections, and against several Gram-positive bacteria (Enterococcus faecalis, Enterococcus faecium, S. epidermidis and Staphylococcus aureus). They also determined the minimum dosage required to inhibit planktonic (free-floating) bacteria.

Activity tests and comparisons with the original polyalthic acid and the drug most prescribed by physicians showed that the analogs developed by the researchers eradicated S. epidermidis, and were active against all the Gram-positive bacteria tested. Although they were less active than the prescribed drug, the results reinforced the importance of additional in vitro and in vivo testing of the substance.

“The advantage of studying polyalthic acid is that previous research has shown that some terpenes don’t lose their activity, and their continuous use therefore doesn’t make bacteria develop resistance,” said Cássia Suemi Mizuno, a researcher at WNE and last author of the article.

The analogs were found to be safe in an analysis of hemolytic activity, i.e. their ability to destroy red blood cells.

Next steps

“Our research is an important contribution to efforts to beat antimicrobial resistance and serves as a foundation on which other groups can made further progress,” Mizuno said.

Next steps will include producing more derivatives with other parts of the polyalthic acid molecule, improving their activity and pursuing prospective partners in the pharmaceutical industry for more research, she added.

Investment in copaiba oil extraction in the Amazon will be needed, as will the recruitment of forest dwellers who are familiar with the native vegetation and can identify the species with the highest level of polyalthic acid content (Copaifera reticulata Ducke).

“It should be stressed that we don’t destroy any trees in our research. Extraction of copaiba oil is like rubber tapping. You just make a groove in the bark of the tree trunk,” Mizuno said.

More information: Marcela Argentin et al, Synthesis and Antibacterial Activity of Polyalthic Acid Analogs, Antibiotics (2023). DOI: 10.3390/antibiotics12071202

Provided by FAPESP 

by Virginia Tech

As the COVID-19 pandemic scattered and isolated people, researchers across Virginia Tech connected for a data-driven collaboration seeking improved drugs to fight the disease and potentially many other illnesses.

A multidisciplinary collaboration spanning several colleges at Virginia Tech resulted in a newly published study, “Data Driven Computational Design and Experimental Validation of Drugs for Accelerated Mitigation of Pandemic-like Scenarios,” in the Journal of Physical Chemistry Letters.

The study focuses on using computer algorithms to generate adaptations to molecules in compounds for existing and potential medications that can improve those molecules’ ability to bind to the main protease, a protein-based enzyme that breaks down complex proteins, in SARS-CoV-2, the virus that causes COVID-19.

This process allows exponentially more molecular adaptations to be considered than traditional trial-and-error methods of testing drugs one by one could allow. Candidate molecule adaptations can be identified among myriad possibilities, then narrowed to a few or one that can be created in a laboratory and tested for effectiveness.

“We present a novel transferable data-driven framework that can be used to accelerate the design of new small molecules and materials, with desired properties, by changing the combination of building blocks as well as decorating them with functional groups,” said Sanket A. Deshmukh, associate professor of chemical engineering in the College of Engineering. A “functional group” is a cluster of atoms that generally retains its characteristic properties, regardless of the other atoms in the molecule.

“Interestingly, the newly designed functionalized drug not only had a better half maximal effective concentration value than its parent drug, but also several of the proposed and used antivirals, including remdesivir,” Deshmukh said, referring to a measure of compound potency.

Moving through all the phases of the study would not have been possible without extensive cross-departmental collaboration.

Four Virginia Tech faculty members—Deshmukh; Anne M. Brown, associate professor with University Libraries and the Department of Biochemistry in the College of Agriculture and Life Sciences; Andrew Lowell, assistant professor in the Department of Chemistry in the College of Science; and James Weger-Lucarelli, assistant professor in the Department of Biomedical Sciences and Pathobiology at the Virginia-Maryland College of Veterinary Medicine—are among 13 co-authors of the published study.

The Deshmukh group’s expertise in developing transferable computational models and frameworks for accelerated design of drug-like small molecules and materials, and Brown’s extensive computational expertise in protein structure-function relationships, meshed seamlessly as a baseline for the study.

“Sanket’s group had a molecular repurposing framework, and I have experience with exploiting protein targets,” said Brown. “Combined with Andrew, who does the synthesis, which is to make the compound, and then James doing the testing and the viral assays, we formed a fantastic collaboration.”

But the faculty members stress that it was the graduate students and postdoctoral students in the laboratories who made the study possible. Nine of them are co-authors: Samrendra K. Singh, chemical engineering; Kelsie King, genetics, bioinformatics, and computational biology; Cole Gannett, chemistry; Christina Chuong, biomedical and veterinary sciences; Soumil Y. Joshi, chemical engineering; Charles Plate, chemical engineering; Parisa Farzeen, chemical engineering; Emily M. Webb, entomology; and Lakshmi Kumar Kunche, chemical engineering.

The professors said the students communicated well with one another without any prompting from their mentors. “I think one of the great things to see is the students really talking with one another and collaborating with one another as well without us having to say ‘Do this,'” Deshmukh said.

Finally, the functionalized molecules were tested against live SARS-CoV-2 in a veterinary college laboratory by Weger-Lucarelli and his team.

“Initial virtual screening of the existing database identified a parent compound that was expected to inhibit the protease of SARS-CoV-2,” Weger-Lucarelli said. “Then the data-driven framework altered the structure of that molecule to enhance that activity. We compared those side by side to show that this new compound that was expected to be more potent against SARS-CoV-2 than the parent compound was, in fact, more potent against SARS-CoV-2.”

The process to develop and test a functionalized molecule against COVID-19 has many potential applications even beyond mitigation of COVID-19. Studies are ongoing among the team to employ the same type of research to find functionalized molecules that may be able to treat hepatitis E, dengue fever and chikungunya, the latter two being mosquito-borne illnesses.

“Another direction we’re going in is that we’re targeting proteases and enzymes from other viruses and trying to design other new molecules,” Lowell said.

The algorithm process also has potential in non-biological uses, Sankit said. The “approach is very versatile and is being applied to functionalize and design other materials such as metal organic frameworks (MOFs), glycomaterials, polymers, etc.,” the paper states.

The assembled interdisciplinary team is planning to continue its collaborations.

“None of us could do this work without the other people in this collaboration,” Weger-Lucarelli said.

“This is a great example of the synergy between going from computational prediction to chemical synthesis to testing in viruses,” Brown said, “and how we at Virginia Tech are really emphasizing that interplay between these three areas and taking that to the next level to develop strong collaborative teams.”

More information: Data Driven Computational Design and Experimental Validation of Drugs for Accelerated Mitigation of Pandemic-like Scenarios, The Journal of Physical Chemistry Letters (2023).

Journal information: Journal of Physical Chemistry Letters 

Provided by Virginia Tech 

by Tohoku University

A group of researchers have unraveled the mysteries behind a recently identified material—zirconium nitride (ZrN)—that helps power clean energy reactions. Their proposed framework will help future designs for transition metal nitrides, paving a path for generating cleaner energy.

The study was published in the journal Chemical Science on July 26, 2023, where it featured as the front cover article.

Anion exchange membrane fuel cells (AEMFC) are devices that use hydrogen and oxygen to make clean electricity through chemical reactions, specifically the hydrogen oxidation reaction and the oxygen reduction reaction (ORR). AEMFCs, with their ability to operate in alkaline conditions, provide a suitable environment for earth-based catalysts, offering a cheaper alternative to other efficient catalyst materials, such as platinum.

Recent studies have shown that ZrN exhibits efficient performances—even outperforming platinum—when used for the ORR in alkaline media. ZrN, while not an Earth-abundant material, is still more cost-effective than alternatives. But what lay behind its impressive performance has remained a mystery to scientists.

“To implement our new theoretical framework for ZrN, we decided to employ surface state analysis, electric field effect simulations, and pH-dependent microkinetic modeling,” explains Hao Li, associate professor at Tohoku University’s Advanced Institute for Materials Research (WPI-AIMR) and corresponding author of the paper.

Surface analysis revealed that ZrN has a very thin layer of HO when it is undergoing ORR. This thin layer helps molecules stick to it in a way that is beneficial for the ORR. Moreover, the electric field effect simulations demonstrate that atomic oxygen sticking to this thin-covered surface undergo minimal changes, thereby sticking moderately.

After performing computer simulations, the researchers found that ZrN reaches the sweet spot of ORR in alkaline conditions.

“Our tested theory works well not just for ZrN but also for other materials like Fe₃N, TiN, and HfN, which are similar to ZrN, meaning our idea explains how these materials can be utilized for clean energy too,” adds Hao. “Our framework will help rationalize and design transition metal nitrides for alkaline ORR.”

In the future, Hao and his team plan to extend this framework to study other industrially significant reactions, such as the oxygen evolution reaction.

More information: Heng Liu et al, Origin of the superior oxygen reduction activity of zirconium nitride in alkaline media, Chemical Science (2023). DOI: 10.1039/D3SC01827J

Journal information: Chemical Science 

Provided by Tohoku University 

by Hebrew University of Jerusalem

Azobenzenes are incredibly versatile and have many potential uses, such as in making tiny machines and improving technology as well as making light controllable drugs. This molecule can switch between two different forms by light. However, the two forms are in equilibrium, which means that a mixture present that prevents optimal use for applications.

Being able to control them with visible light and enrich only one form opens up new possibilities for these applications, making them more efficient and accessible.

Azobenzenes have traditionally required ultraviolet light for photoisomerization. However, a new approach promises to change the game. Profs. Igor Schapiro from Hebrew University of Jerusalem, Rafal Klajn from the Weizmann Institute of Science and Institute of Science and Technology Austria, and Arri Priimagi from Tampere University along with a team of researchers, have introduced a novel concept termed “disequilibration by sensitization under confinement” or DESC.

This innovative approach offers for the first time the possibility of prompting a specific molecular transformation, specifically the conversion from an “E” to a “Z” state. They can be thought of as an “on” and “off” form in applications. This change can be triggered by visible light, including wavelengths in the red part of the visible spectrum.

The study, titled “Disequilibrating azobenzenes by visible-light sensitization under confinement,” was published in the journal, Science.

What makes azobenzene molecules particularly interesting is their ability to undergo changes in their shape in response to specific types of light, including ultraviolet and visible light. This phenomenon, known as photoisomerization, enables azobenzenes to transition between two distinct shapes or isomers, the “E” and “Z” isomers. This unique attribute holds immense significance, as it unlocks a diverse spectrum of applications spanning nanotechnology, data storage, drug delivery, materials science, and biological research.

In essence, azobenzenes serve as pivotal elements in numerous scientific and technological advancements.

“Through our computational studies and quantum chemical calculations, we’ve illuminated the path to an innovative approach, which not only advances the fundamental field of azobenzene but also paves the way for practical applications. These applications harness the power of visible light, including red wavelength of light,” said Prof. Igor Schapiro, Hebrew University of Jerusalem

Azobenzenes are pivotal components in a wide range of technologies, from molecular switches and actuators to data storage and drug delivery systems. Until now, their photoisomerization necessitated ultraviolet light, limiting their applicability. However, DESC represents a significant breakthrough, offering a supramolecular approach that enables controlled E-to-Z isomerization with harmless light.

This pioneering research opens up exciting new avenues for the utilization of azobenzenes across various fields. By broadening the range of light wavelengths that can induce isomerization, DESC promises to enhance the efficiency and applicability of azobenzene-based technologies.

More information: Julius Gemen et al, Disequilibrating azobenzenes by visible-light sensitization under confinement, Science (2023). DOI: 10.1126/science.adh9059. www.science.org/doi/10.1126/science.adh9059

Journal information: Science 

Provided by Hebrew University of Jerusalem 

by Science China Press

Understanding how voltage drives nanoscale electrocatalysts to initiate reactions is a fundamental scientific question. This is especially challenging when dealing with non-metallic electrocatalysts due to their low inherent carrier concentration, which leads to poor conductivity. When voltage is applied at the non-metal/solution interface, the situation becomes more complex than in the case of metal/solution interfaces.

One notable complexity is the significant potential drop within the non-metal, causing the surface potential to often deviate from the back potential. Analyzing the driving force for chemical reactions by applying classical metal models to non-metals can result in substantial inaccuracies.

Up until now, distinguishing the potential distribution between the nonmetallic catalyst and the EDL still relies on complex theoretical calculations. The actual potential drop across the semiconductor-electrolyte interface remains unknown, due to the lacks of in in-situ techniques.

Moreover, conventional electrochemical characterization only provides the ensemble information for electrode materials, neglecting the spatial heterogeneity in the electronic structures of catalysts. Therefore, a spatially resolved in-situ characterization technique is highly needed.

In a new research article published in National Science Review, scientists at Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Xiamen University, University of Chinese Academy of Sciences, Imperial College London autonomously constructed an in-situ surface potential microscope and successfully measured the surface potential of the basal plane of 2H molybdenum disulfide under various voltages.

This achievement addresses the experimental challenge of directly measuring the potential distribution at the non-metal/solution interface. The research findings highlight a notable difference in how the surface potential of semiconductors changes with applied voltage compared to metals.

When applying voltage from positive to negative, semiconductors shift from maintaining a stable surface potential to displaying variations, gradually resembling the behavior of metals. Scientists further clarified the differences in potential drop values at various applied voltages between the semiconductor (ΔV_sem) and the double layer (ΔV_edl).

They vividly explained how, in a solution environment, the semiconductor’s Fermi level and band structure evolve, demonstrating a transformation of the semiconductor into a highly conductive semimetal.

To further investigate the role of voltage in electrocatalytic reactions, scientists employed atomic force-scanning electrochemical microscopy (AFM-SECM) to study electron transfer (ET) and hydrogen evolution reaction (HER) imaging on molybdenum disulfide. In ET imaging, the semiconductor’s basal plane exhibited strong electron transfer capability, comparable to that of the semimetal edge. However, HER imaging revealed catalytic inertness at the basal plane.

Nano-electrochemical imaging results indicated that voltage only affects the ET step. Due to the absence of hydrogen adsorption sites on the basal plane (i.e., chemical sites), voltage cannot drive the electrons on the basal plane to further participate in chemical reactions. This work paves the way for the rational design of efficient nonmetallic electrocatalysts based on the understanding of how voltage acts on nonmetallic catalysts at the nanoscale.

More information: Ziyuan Wang et al, Visualizing the role of applied voltage in non-metal electrocatalysts, National Science Review (2023). DOI: 10.1093/nsr/nwad166

Provided by Science China Press 

by University of Eastern Finland

Boosting virtual screening with machine learning allowed for a 10-fold time reduction in the processing of 1.56 billion drug-like molecules. Researchers from the University of Eastern Finland teamed up with industry and supercomputers to carry out one of the world’s largest virtual drug screens.

In their efforts to find novel drug molecules, researchers often rely on fast computer-aided screening of large compound libraries to identify agents that can block a drug target. Such a target can, for instance, be an enzyme that enables a bacterium to withstand antibiotics or a virus to infect its host. The size of these collections of small organic molecules has seen a massive surge over the past years.

With libraries growing faster than the speed of the computers needed to process them, the screening of a modern billion-scale compound library against only a single drug target can take several months or years—even when using state-of-the-art supercomputers. Therefore, quite evidently, faster approaches are desperately needed.

In a study published in the Journal of Chemical Information and Modeling, Dr. Ina Pöhner and colleagues from the University of Eastern Finland’s School of Pharmacy teamed up with the host organization of Finland’s powerful supercomputers, CSC—IT Center for Science Ltd—and industrial collaborators from Orion Pharma to study the prospect of machine learning in the speed-up of giga-scale virtual screens.

Before applying artificial intelligence to accelerate the screening, the researchers first established a baseline: In a virtual screening campaign of unprecedented size, 1.56 billion drug-like molecules were evaluated against two pharmacologically relevant targets over almost six months with the help of the supercomputers Mahti and Puhti, and molecular docking. Docking is a computational technique that fits the small molecules into a binding region of the target and computes a “docking score” to express how well they fit. This way, docking scores were first determined for all 1.56 billion molecules.

Next, the results were compared to a machine learning-boosted screen using HASTEN, a tool developed by Dr. Tuomo Kalliokoski from Orion Pharma, a co-author of the study.

“HASTEN uses machine learning to learn the properties of molecules and how those properties affect how well the compounds score. When presented with enough examples drawn from conventional docking, the machine learning model can predict docking scores for other compounds in the library much faster than the brute-force docking approach,” Kalliokoski explains.

Indeed, with only 1% of the whole library docked and used as training data, the tool correctly identified 90% of the best-scoring compounds within less than 10 days.

The study represented the first rigorous comparison of a machine learning-boosted docking tool with a conventional docking baseline on the giga-scale. “We found the machine learning-boosted tool to reliably and repeatedly reproduce the majority of the top-scoring compounds identified by conventional docking in a significantly shortened time frame,” Pöhner says.

“This project is an excellent example of collaboration between academia and industry, and how CSC can offer one of the best computational resources in the world. By combining our ideas, resources and technology, it was possible to reach our ambitious goals,” said Professor Antti Poso, who leads the computational drug discovery group within the University of Eastern Finland’s DrugTech Research Community.

Studies on a comparable scale remain elusive in most settings. Thus, the authors released large datasets generated as part of the study into the public domain. Their ready-to-use screening library for docking enables others to speed up their respective screening efforts, with 1.56 billion compound-docking results for two targets that can be used as benchmarking data.

This data will encourage the future development of tools to save time and resources and will ultimately advance the field of computational drug discovery.

More information: Toni Sivula et al, Machine Learning-Boosted Docking Enables the Efficient Structure-Based Virtual Screening of Giga-Scale Enumerated Chemical Libraries, Journal of Chemical Information and Modeling (2023). DOI: 10.1021/acs.jcim.3c01239

Journal information: Journal of Chemical Information and Modeling 

Provided by University of Eastern Finland 

by Addison Dehaven, South Dakota State University

Next to water, coffee is the most popular beverage on Earth and is the world’s second most traded good, trailing only oil. It is estimated that humans drink more than 2 billion cups of coffee per day with over 60% of Americans having a cup each day. As a result, over 8 million tons of spent coffee grounds are disposed of on an annual basis.

What if, instead of ending up in a landfill, those coffee grounds could be used as a sustainable, climate-friendly packaging material?

While this may seem like wishful thinking, a new study from Srinivas Janaswamy, associate professor in South Dakota State University’s Department of Dairy and Food Science, has revealed how spent coffee grounds can be made into biodegradable films—material that could one day replace plastics.

The study, titled “Biodegradable, UV-blocking, and antioxidant films from lignocellulosic fibers of spent coffee grounds,” was published in the International Journal of Biological Macromolecules.

Alternatives to plastic

Plastics are strong, flexible and relatively inexpensive to produce, making them a near “perfect” material for packaging. Plastics, however, pose a serious environmental problem. While recyclable, most plastics end up as litter or in landfills, where they take 700 years to biodegrade. In the oceans, miles of plastic garbage patches—most notably, the Great Pacific Garbage Patch, which is currently the size of Texas and growing—float aimlessly, underlining the growing environmental crisis that an over-reliance on plastic has created.

Of growing concern are microplastics, a relatively new scientific discovery in which microscopic pieces of plastics are finding their way into the food and water that humans consume. Little to no research on the long-term health effects of microplastics on humans has been conducted thus far.

A safe, sustainable and climate-friendly plastic alternative is needed.

“Plastics constitute a wide range of materials designed to meet many daily needs,” Janaswamy said. “Replacing all existing plastics is far from possible at this stage. However, substituting low-cost daily commodity-used conventional plastics, which occupy the most considerable fraction of the environmental contaminants, is feasible and can be achieved.”

Why coffee grounds?

Over the past few years, Janaswamy has focused his research efforts on creating biodegradable alternatives to plastic, often from agricultural byproducts. Previously, Janaswamy has prepared films from the cellulose-rich peels of avocados and corn stover.

“This project continues my ongoing efforts to prepare films that could replace plastics,” Janaswamy said.

Spent coffee grounds were chosen as the source material for a few different reasons. First, spent coffee grounds are widely available with millions of tons produced annually. While most end up in landfills, some are used for other things, like gardening. While this may seem like an environmentally conscious move, as Janaswamy points out, it actually can cause environmental problems.

“Generally, we discard the coffee ground grounds after we make our coffee,” Janaswamy said. “Some of us use them for compositing, gardening and other things. Ironically, such a process demands high amounts of oxygen and releases a good amount of methane, which contributes to global warming.”

Second, as emerging economies begin adding chain coffee shops—like Starbucks—the amount of spent coffee grounds will only increase. Using this otherwise unused resource for biodegradable films is a sustainable and economical solution to the plastic crisis.

Finally, spent coffee grounds contain lignocellulosic fibers, the material needed to make the films.

Coffee into film

To prepare the films, the research team first extracted lignocellulosic fibers from the spent coffee grounds. A green chemical modification process was then deployed to make the film more suitable for packaging.

The resulting films were able to biodegrade within 45 days in the soil while also having high tensile strength. Further, the films also had some unique properties of which researchers took note.

“Interestingly, these films could block significant amounts of UV radiation and display antioxidant properties,” Janaswamy explained. “I sincerely believe this research outcome opens up new applications for spent coffee grounds.”

While this should still be considered “stage one” of turning spent coffee grounds into films, the results from this study showed significant promise.

“The potential for plastic-replacing films from the widely discarded but plentiful and sustainable spent coffee grounds remain unscathed and exciting toward value creation,” Janaswamy said.

Sajal Bhattarai, an SDSU graduate and a doctoral candidate at Purdue University, collaborated with Janaswamy on this research.

More information: Sajal Bhattarai et al, Biodegradable, UV-blocking, and antioxidant films from lignocellulosic fibers of spent coffee grounds, International Journal of Biological Macromolecules (2023). DOI: 10.1016/j.ijbiomac.2023.126798

Provided by South Dakota State University 

by José Tadeu Arantes, FAPESP

Researchers at São Paulo State University (UNESP) in Brazil have developed a strategy for removing glyphosate, one of the world’s most frequently used herbicides, from water. Inspired by the concept of the circular economy, the technique is based on sugarcane bagasse, a waste material produced by sugar and ethanol plants.

“Isolated and chemically functionalized sugarcane bagasse fibers can be used as adsorbent material. Glyphosate adheres to its surface and is removed as a water contaminant by filtration, decantation or centrifugation,” Maria Vitória Guimarães Leal, told Agência FAPESP.

She is the first author of an article on the research published in the journal Pure and Applied Chemistry. Adsorption is a process whereby molecules dispersed in a liquid or gaseous medium adhere to a solid insoluble surface, which is typically porous.

Owing to its low cost and high potential to raise crop yields, glyphosate is widely used to control the growth of unwanted plants, such as weeds, invasive species and agricultural pests, but scientific studies have shown that it can be a human health hazard and in particular may pose a cancer risk.

Application of glyphosate-containing products is restricted or banned in Austria, Bulgaria, Colombia, Costa Rica, Denmark, El Salvador, Germany and Greece, among other countries. In Brazil, however, annual use of such products averages 173,150.75 metric tons. Part of them is borne away by rain into rivers, wells and other aquatic environments.

Scientists at UNESP’s School of Sciences and Technology (FCT) in Presidente Prudente found a way to remove glyphosate products from water in research led by postdoctoral fellow Guilherme Dognani and Aldo Eloizo Job, a professor at FCT-UNESP.

How it works

Dognani explained the procedure. “The bagasse is shredded and the cellulose isolated by separating it from the hemicellulose and lignin. The cellulose fibers are then functionalized by adding quaternary ammonia groups to their surface so that the material is positively charged. The resulting cationic cellulose microfibers bind easily to glyphosate,” he said.

Leal added that there are certain favorable conditions, such as pH variation, which was the focus of the study. “When pH is varied, both the adsorbent material and the glyphosate display different molecular configurations. The most efficient level for interaction between them, inducing the most adsorption and hence optimal removal, is pH 14,” he said.

To evaluate adsorption capacity, the researchers prepared fractions of a glyphosate solution with pH 2, 6, 10 and 14, measured using a pH meter. They then added to each fraction identical amounts of functionalized cellulose microfiber.

The flasks with the solution contaminated by glyphosate plus cellulose were agitated for 24 hours. In accordance with the procedure described in the literature, they were then heated in a water bath until the reaction occurred, cooled to room temperature and analyzed by visible light spectrophotometry. Removal efficiency was calculated as a ratio of initial to final glyphosate levels in each sample, and adsorption capacity was calculated as a function of pH.

More information: Maria Vitória Guimarães Leal et al, pH dependence of glyphosate adsorption from aqueous solution using a cationic cellulose microfibers (cCMF) biosorbent, Pure and Applied Chemistry (2023). DOI: 10.1515/pac-2022-1205

Provided by FAPESP 

by Ecole Polytechnique Federale de Lausanne

Metal-organic frameworks (MOFs) are a class of materials that contain nano-sized pores. These pores give MOFs record-breaking internal surface areas, which make them extremely versatile for a number of applications: separating petrochemicals and gases, mimicking DNA, producing hydrogen, and removing heavy metals, fluoride anions, and even gold from water are just a few examples.

In the gas-separation domain, MOFs are particularly interesting for separating hydrogen from nitrogen, which is crucial for clean energy production, fuel cell efficiency, ammonia synthesis, and various industrial processes. Hydrogen-nitrogen separation also has a number of environmental benefits, making it integral to advancing sustainable technologies and industrial practices.

Now, a team of researchers led by Professor Kumar Varoon Agrawal at EPFL’s School of Basic Sciences have developed MOF film with smallest possible thickness that can perform record levels of hydrogen-nitrogen separation. The researchers worked with a type of MOFs known as zeolitic imidazolate frameworks (ZIFs), which have garnered considerable attention for their potential in molecular separations, sensing, and other applications.

Their research is published in Nature Materials.

To make the films, the researchers used an innovative crystallization method that capitalizes on the precise alignment of ultra-dilute precursor mixtures with the underlying crystalline substrate. By carefully controlling precursor concentrations and interactions with the substrate, the team were able to suppress out-of-plane growth—a common problem in making thin films.

The approach paid off: Within a matter of minutes, and at room temperature, the scientists were able to fabricate macroscopically uniform two-dimensional (2D) ZIF films with unprecedented thickness: just one structural unit, measuring only two nanometers. The scientists also showed that the process is scalable preparing films with area of hundreds of square centimeters. The breakthrough overcomes conventional methods, which have limited ZIF film thickness to 50 nanometers, making widespread use difficult.

The ZIF film has a unique configuration: a nanometer-thick film with a uniform array of hydrogen-sieving six-membered zinc-imidazolate coordination ring. Kumar Agrawal explains, “This allows for an exceptional combination of hydrogen flux and selectivity, holding immense potential for highly efficient gas-separation applications.”

More information: Unit-cell-thick zeolitic imidazolate framework films for membrane application, Nature Materials (2023). DOI: 10.1038/s41563-023-01669-z , www.nature.com/articles/s41563-023-01669-z

Journal information: Nature Materials 

Provided by Ecole Polytechnique Federale de Lausanne 

by University of Amsterdam

What chemicals are we exposed to on a daily basis? That is the central question of “non-targeted analysis” or NTA, an emerging field of analytical science that aims to identify all chemicals around us. A daunting task, because how can you be sure to detect everything if you don’t know exactly what you’re looking for?

In a paper published in Environmental Science and Technology, researchers at the Universities of Amsterdam (UvA, the Netherlands) and Queensland (UQ, Australia) have assessed this problem. In a meta-analysis of NTA results published over the past six years, they estimate that less than 2% of all chemicals have been identified.

According to Viktoriia Turkina who performed the research as a Ph.D. student with Dr. Saer Samanipour at the UvA’s Van ‘t Hoff Institute for Molecular Sciences, this limitation underscores the urgent need for a more proactive approach to chemical monitoring and management. “We need to incorporate more data-driven strategies into our studies to be able to effectively protect the human and environmental health,” she says.

Samanipour explains that current monitoring of chemicals is rather limited since it’s expensive, time consuming, and requires specialized experts. “As an example, in the Netherlands we have one of the most sophisticated monitoring programs for chemicals known to be of concern to human health. Yet we target less than 1,000 chemicals. There are far more chemicals out there that we don’t know about.”

A vast chemical space

To deal with those chemicals, some 15 to 20 years ago the concept of non-targeted analysis was introduced to look at possible exposure in an unbiased manner. The idea is to take a sample from the environment (air, water, soil, sewer sludge) or the human body (hair, blood, etc.) and analyze it using well-established techniques such as chromatography coupled with high resolution mass spectroscopy.

The challenge then is to trace the obtained signal back to the structures of chemicals that may be present in the sample. This will include already known chemicals, but also chemicals of which the potential presence in the environment is yet unknown.

In theory, this “chemical space” includes as many as 10⁶⁰ compounds, an incomprehensible number that exceeds the number of stars in the universe by far. On the other hand, the number of organic and inorganic substances published in the scientific literature and public databases is estimated at around 180 million.

To make their research more manageable, Turkina, Samanipour and co-workers focused on a subset of 60,000 well-described compounds from the NORMAN database. Turkina says, “This served as the reference to establish what is covered in NTA studies, and more importantly, to develop an idea about what is being overlooked.”

The vast ‘exposome’ of chemicals that humans are exposed to on a daily basis is a sign of our times, according to Samanipour.

“These days we are soaking in a giant ocean of chemicals. The chemical industry is part of that, but also nature is running all a whole bunch of reactions that result in exposure. And we expose ourselves to chemicals by the stuff we use—think for instance of the problem of microplastics. To solve all this we have to be able to go beyond pointing fingers. With our research, we hope to contribute to finding a solution together. Because we all are in the same boat.”

Much room for improvement

The meta analysis, which included 57 NTA papers, revealed that only around 2% of the estimated chemical space was covered. This can indicate that the actual exposure to chemicals is indeed quite low, however, it can also point to shortcomings in the applied analyses. According to Turkina and Samanipour, the latter is indeed the case. They focused on NTA studies applying liquid chromatography coupled with high resolution mass spectrometry (LC-HRMS) -one of the most comprehensive methods for the analysis of complex environmental and biological samples.

It turned out that there was much room for improvement. For instance in sample preparation, they observed a bias towards specific compounds rather than capturing a more diverse set of chemicals. They also observed poor selection and inconsistent reporting of LC-HRMS parameters and data acquisition methods.

“In general,” Samanipour says, “the chemical analysis community is to a great extent driven by the available technology that vendors have developed for specific analysis purposes. Thus the instrumental set-up and data processing methods are rather limited when it comes to non-targeted analysis.”

To Samanipour, the NTA approach is definitely worth pursuing. “But we need to develop it further and push it forward. Together with vendors we can develop new powerful and more versatile analytical technologies, as well as effective data analysis protocols.”

He also advocates a data-driven approach were the theoretical chemical space is “back calculated” towards a subset of chemicals that are highly likely to be present in our environment. “Basically we have to better understand what is the true chemical space of exposure. And once those boundaries are defined, then it becomes a lot easier to assess that number of 2% we have determined.”

More information: Tobias Hulleman et al, Critical Assessment of the Chemical Space Covered by LC–HRMS Non-Targeted Analysis, Environmental Science & Technology (2023). DOI: 10.1021/acs.est.3c03606

Journal information: Environmental Science and Technology  , Environmental Science & Technology 

Provided by University of Amsterdam