Category: Chemistry

In a recent paper in Nature Communications, researchers at the Industrial Sustainable Chemistry group led by Prof. Gert-Jan Gruter take an important step towards the production of fully bio-based, rigid polyesters.

They present a simple, yet innovative, synthesis strategy to overcome the inherently low reactivity of bio-based secondary diols and arrive at polyesters that have very good mechanical- and thermal properties, and at the same time high molecular weights. It enables the production of very strong and durable bio-based plastics from building blocks that are already commercially available.

The research described in the Nature Communications paper was carried out within the RIBIPOL project funded by the Dutch Research Council NWO with contributions from industry, notably LEGO and Avantium. The toy company supported the project as part of the search for non-fossil alternatives for its plastic bricks. Avantium is interested in bottle- and film applications. First author of the paper is Ph.D. student Daniel Weinland, who graduated on October 27. In total, five Ph.D. students are involved in the RIBIPOL project, of which two have defended their thesis recently.

Rigidity is key

In general, polyester plastics are synthesized from small dialcohol and diacid molecules. These monomers are coupled in a condensation reaction, resulting in a long polymer chain of molecular building blocks in an alternating fashion. The macroscopic material properties result both from the number of building blocks that make up the polymer chain, and from the inherent properties of the monomers.

In particular their rigidity is key to a firm, strong and durable plastic. In this regard, the glucose-derived dialcohol isosorbide is unique among potential bio-based monomers. It has a very rigid molecular structure and is already industrially available.

However, isosorbide is rather unreactive, and in the past two decades it has proven quite challenging to obtain useful isosorbide-based polyesters. It was nearly impossible to arrive at sufficiently long polymer chains (to achieve a certain ductility) while incorporating sufficiently high amounts of isosorbide (to arrive at a strong and durable material).

Incorporating an aryl alcohol

Weinland and his RIBIPOL colleagues have overcome this impasse by incorporating an aryl alcohol in the polymerization process. This leads to in situ formation of reactive aryl esters and a significant enhancement of the end group reactivity during polycondensation, the last stage of polyester synthesis when isosorbides low reactivity inhibits chain growth in traditional melt polyesterification. As a result, high molecular weight materials could be produced with incorporation of high fractions of the bio-based, rigid secondary diol, even up to 100 mol%.

For the first time, high molecular weight poly(isosorbide succinate) could be produced, the polyester obtained from isosorbide and succinic acid. The resulting strong plastics outperform existing plastics like PET in terms of heat resistance, which is for instance relevant for re-use—think of washing bottles that takes place at 85 °C. The isosorbide-based polymers also show promising barrier and mechanical properties that can outperform common fossil-based materials.

The novel polymerization approach described in the paper is characterized by operational simplicity and the use of standard polyester synthesis equipment. It suits both existing and novel polyester compositions; the researchers foresee exploration of previously inaccessible polyester compositions based on monomers with a low reactivity but also the application of similar methods in other classes of polymers such as polyamides and polycarbonates.

More information: Daniel H. Weinland et al, Overcoming the low reactivity of biobased, secondary diols in polyester synthesis, Nature Communications (2022). DOI: 10.1038/s41467-022-34840-2

Journal information: Nature Communications 

Provided by University of Amsterdam 

A team of University of Illinois Urbana-Champaign Material Science and Engineering researchers have solved a long-standing puzzle about lower measured thermal conductivity values of cubic silicon carbide (3C-SiC) bulk crystals in the literature than the structurally more complex hexagonal phase SiC polytype (6H-SiC). The new measured thermal conductivity of bulk 3C-SiC has the second highest thermal conductivity among inch-scale large crystals, second only to diamond.

Professor David Cahill (Grainger Distinguished Chair in Engineering and co-director of the IBM-Illinois Discovery Accelerator Institute) and Dr. Zhe Cheng (Postdoc) report an isotropic high thermal conductivity of 3C-SiC crystals that exceeds 500 W m^-1K^-1. The team collaborated with Air Water, Inc, based in Japan, to grow high-quality crystals, with the thermal conductivity measurements performed at UIUC in the MRL Laser and Spectroscopy suite. Their results were recently published in Nature Communications.

Silicon carbide (SiC) is a wide bandgap semiconductor used commonly in electronic applications and has various crystalline forms (polytypes). In power electronics, a significant challenge is thermal management of high localized heat flux that can lead to overheating of devices and the degradation of device performance and reliability in the long-term. Materials with high thermal conductivity (κ) are critical in thermal management design.

Hexagonal phase SiC polytypes (6H and 4H) are the most widely used and extensively studied, whereas the cubic phase SiC polytype (3C) is less understood, despite it having the potential to have the best electronic properties and higher κ. Cahill and Zhe explain that there has been a long-standing puzzle about the measured thermal conductivity of 3C-SiC in the literature: 3C-SiC is lower than that of the structurally more complex 6H-SiC phase and measures lower than the theoretically predicted κ value.

This is a contradiction of predicted theory that structural complexity and thermal conductivity are inversely related (as structural complexity goes up, thermal conductivity should go down).

Zhe says that 3C-SiC is “not a new material, but the issue researchers have had before is poor crystal quality and purity, causing them to measure lower thermal conductivity than other phases of silicon carbide.” Boron impurities contained in the 3C-SiC crystals cause exceptionally strong resonant phonon scattering, which significantly lowers its thermal conductivity.

Wafer-scale 3C-SiC bulk crystals produced by Air Water Inc. were grown by low-temperature chemical vapor deposition and had high crystal quality and purity. The team observed high thermal conductivity from the high purity and high crystal quality 3C-SiC crystals.

Zhe says that “the measured thermal conductivity of 3C-SiC bulk crystals in this work is ~50% higher than the structurally more complex 6H-SiC, consistent with predictions that structural complexity and thermal conductivity are inversely related. Moreover, the 3C-SiC thin films grown on Si substrates have record-high in-plane and cross-plane thermal conductivities, even higher than that of diamond thin films with equivalent thicknesses.”

The high thermal conductivity measured in this work ranks 3C-SiC second to single crystal diamond among inch-scale crystals, which has the highest κ among all natural materials. However, for thermal management materials, diamond is limited by its high cost, small wafer size, and difficulty in integration with other semiconductors.

3C-SiC is cheaper than diamond, can easily be integrated with other materials, and can be grown to large wafer sizes, making it a suitable thermal management material or an excellent electronic material with a high thermal conductivity for scalable manufacturing.

Cahill says, “The unique combination of thermal, electrical, and structural properties of 3C-SiC can revolutionize the next generation of electronics by using it as active components (electronic materials) or thermal management materials,” since 3C-SiC has the highest thermal conductivity among all SiC polytypes and helps facilitate device cooling and reduce power consumption.

The high thermal conductivity of 3C-SiC has potential to impact applications such as power electronics, radio-frequency electronics, and optoelectronics.

More information: Zhe Cheng et al, High thermal conductivity in wafer-scale cubic silicon carbide crystals, Nature Communications (2022). DOI: 10.1038/s41467-022-34943-w

Journal information: Nature Communications 

Provided by University of Illinois Grainger College of Engineering 

Researchers led by Prof. Chen Tao at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS), in cooperation with researchers at Ningbo University, have developed a novel breakage-resistant conductive hydrogel (BRC hydrogel) with excellent mechanical reliability, extending the service life of triboelectric nanogenerators (TENGs). This study was published in the Chemical Engineering Journal.

Benefitting from the facile fabrication, multiple structures, stable output and high energy conversion efficiency, TENGs have provided effective energy supply for the continuous operation of the Internet of Things (loT) system. Among them, hydrogel-based TENGs (H-TENGs) shows great advantages in the field of flexible wearable devices and self-powered applications. However, the poor mechanical properties of hydrogel electrode lead to a low mechanical reliability during the long-term operation, thus shortening the service life of H-TENGs.

Based on the Hofmeister effect on starch polymers, the researchers developed a facile and efficient solvent-exchange strategy to prepare BRC hydrogels with ultrahigh mechanical reliability. The formation of the bundling starch chains endows the BRC hydrogel with excellent modulus of ~0.87 MPa, fracture energy of 7.45 kJ/m², anti-puncture capacity of ~15 Mpa and long-term stability.

In addition, the electrical properties for the BRC hydrogel have improved remarkably, since abundant free ions (i.e. Na⁺, Cit^–) were introduced into the BRC hydrogel.

Employing this BRC hydrogel as electrode material, the researchers fabricated the BRC hydrogel based TENG (BRCH-TENG) with excellent electrical output performances and mechanical safety. The stable mechanical property under continuous physical impact contributes to improving the long-term stability of the BRCH-TENG, thus prolonging its service life upon accidental physical impact.

Furthermore, the fabricated BRCH-TENG shows bright and broad application prospects in the field of walking energy harvesting, real-time motion stride detection and information communication.

More information: Rui Li et al, Breakage-resistant hydrogel electrode enables ultrahigh mechanical reliability for triboelectric nanogenerators, Chemical Engineering Journal (2022). DOI: 10.1016/j.cej.2022.140261

Provided by Chinese Academy of Sciences 

Even as detailed images of distant galaxies from the James Webb Space Telescope show us more of the greater universe, scientists still disagree about how life began here on Earth. One hypothesis is that meteorites delivered amino acids—life’s building blocks—to our planet. Now, researchers reporting in ACS Central Science have experimentally shown that amino acids could have formed in these early meteorites from reactions driven by gamma rays produced inside the space rocks.

Ever since Earth was a newly formed, sterile planet, meteorites have been hurtling through the atmosphere at high speeds toward its surface. If the initial space debris had included carbonaceous chondrites—a class of meteorite whose members contain significant amounts of water and small molecules, such as amino acids—then it could have contributed to the evolution of life on Earth. However, the source of amino acids in meteorites has been hard to pinpoint.

In previous lab experiments, Yoko Kebukawa and colleagues showed that reactions between simple molecules, such as ammonia and formaldehyde, can synthesize amino acids and other macromolecules, but liquid water and heat are required. Radioactive elements, such as aluminum-26 (²⁶Al)—which is known to have existed in early carbonaceous chondrites—release gamma rays, a form of high-energy radiation, when they decay. This process could have provided the heat needed to make biomolecules. So, Kebukawa and a new team wanted to see whether radiation could have contributed to the formation of amino acids in early meteorites.

The researchers dissolved formaldehyde and ammonia in water, sealed the solution in glass tubes and then irradiated the tubes with high-energy gamma rays produced from the decay of cobalt-60. They found that the production of α-amino acids, such as alanine, glycine, α-aminobutyric acid and glutamic acid, and β-amino acids, such as β-alanine and β-aminoisobutyric acid, rose in the irradiated solutions as the total gamma-ray dose increased.

Based on these results and the expected gamma ray dose from the decay of ²⁶Al in meteorites, the researchers estimated that it would have taken between 1,000 and 100,000 years to produce the amount of alanine and β-alanine found in the Murchison meteorite, which landed in Australia in 1969.

This study provides evidence that gamma ray-catalyzed reactions can produce amino acids, possibly contributing to the origin of life on Earth, the researchers say.

More information: Gamma-Ray-Induced Amino Acid Formation in Aqueous Small Bodies in the Early Solar System, ACS Central Science (2022). DOI: 10.1021/acscentsci.2c00588, pubs.acs.org/doi/abs/10.1021/acscentsci.2c00588

Journal information: ACS Central Science 

Provided by American Chemical Society 

Everyone knows someone who has had cancer. In 2020, around 19 million new cases—and around 10 million deaths—were registered worldwide. Treatments are improving all the time, but can damage healthy cells or have severe side effects that are hard on patients. In the search for new, more targeted cancer drugs, traditional medicine offers many possible candidates.

A team of Polish scientists led by Magdalena Winkiel at Adam Mickiewicz University, publishing today in Frontiers in Pharmacology, has reviewed the bioactive compounds called glycoalkaloids, found in vegetables like potatoes and tomatoes, to demonstrate their potential to treat cancer.

“Scientists around the world are still searching for the drugs which will be lethal to cancer cells but at the same time safe for healthy cells,” said Winkiel.

“It is not easy despite the advances in medicine and powerful development of modern treatment techniques. That is why it might be worth going back to medicinal plants that were used years ago with success in the treatment of various ailments. I believe that it is worth reexamining their properties and perhaps rediscovering their potential.”

Making medicine from poison

Winkiel and her colleagues focused on five glycoalkaloids—solanine, chaconine, solasonine, solamargine and tomatine—that are found in crude extracts of the Solanaceae family of plants, also known as nightshades. This family contains many popular food plants, and many that are toxic, frequently because of the alkaloids they produce as a defense against animals that eat plants. But the correct dose can turn a poison into a medicine: Once scientists have found a safe therapeutic dose for alkaloids, they can be powerful clinical tools.

Glycoalkaloids in particular inhibit cancer cell growth and may promote cancer cell death. These are key target areas for controlling cancer and improving patient prognoses, so have huge potential for future treatments. In silico studies—an important first step—suggest that the glycoalkaloids aren’t toxic and don’t risk damaging DNA or causing future tumors, although there may be some effects on the reproductive system.

“Even if we cannot replace anti-cancer drugs that are used nowadays, maybe combined therapy will increase the effectiveness of this treatment,” Winkiel suggested. “There are many questions, but without detailed knowledge of the properties of glycoalkaloids, we will not be able to find out.”

From tomatoes to treatments

One necessary step forward is using in vitro and model animal studies to determine which glycoalkaloids are safe and promising enough to test in humans. Winkiel and her colleagues highlight glycoalkaloids derived from potatoes, like solanine and chaconine—although the levels of these present in potatoes depend on the cultivar of potato and the light and temperature conditions to which the potatoes are exposed.

Solanine stops some potentially carcinogenic chemicals from transforming into carcinogens in the body and inhibits metastasis. Studies on a particular type of leukemia cells also showed that at therapeutic doses, solanine kills them. Chaconine has anti-inflammatory properties, with the potential to treat sepsis.

Meanwhile, solamargine—which is mostly found in eggplant—stops liver cancer cells from reproducing. Solamargine is one of several glycoalkaloids that could be crucial as a complementary treatment, because it targets cancer stem cells which are thought to play a significant role in cancer drug resistance.

Solasonine, which is found in several plants from the nightshade family, is also thought to attack cancer stem cells by targeting the same pathway. Even tomatoes offer potential for future medicine, with tomatine supporting the body’s regulation of the cell cycle so that it can kill cancer cells.

Further research will be needed to determine how this in vitro potential can best be turned into practical medicine, Winkiel and her team noted. There is some reason to believe that high-temperature processing improves glycoalkaloid properties, and nanoparticles have recently been found to improve transmission of glycoalkaloids to cancer cells, boosting drug delivery.

However, the glycoalkaloids’ mechanisms of action must be better understood, and all potential safety concerns must be scrutinized, before patients can benefit from cancer drugs straight out of the vegetable patch.

More information: Anticancer activity of glycoalkaloids from Solanum plants: a review, Frontiers in Pharmacology (2022). DOI: 10.3389/fphar.2022.979451

Journal information: Frontiers in Pharmacology 

Provided by Frontiers 

In search of new biomarkers for nutrition and health studies, a research team from the Leibniz Institute for Food Systems Biology at the Technical University of Munich (LSB) has identified and structurally characterized three metabolites that could be considered as specific markers for individual coffee consumption.

These are degradation products of a group of substances that are formed in large quantities during coffee roasting but are otherwise rarely found in other foods. This and the fact that the potential biomarkers can be detected in very small amounts of urine make them interesting for future human studies.

According to Statista, coffee is by far the most popular hot beverage in Germany. On average, around 168 liters are consumed per person per year. It is not only a stimulant, but also has positive health properties. For example, numerous observational studies indicate that moderate coffee consumption is associated with a reduced risk of type 2 diabetes or liver disease.

Biomarkers instead of self-reporting

However, with regard to the amounts of coffee drunk, such observational studies rely on participants’ self-reports, which are difficult to verify. “Complementary studies would therefore be desirable in which coffee consumption could be objectively verified using biomarkers in order to determine the health value of coffee even more reliably,” says Roman Lang, who heads the Biosystems Chemistry & Human Metabolism research group at LSB.

Although earlier studies had already pointed to biomarker candidates, research on this had stalled for years. The substances previously detected were metabolic intermediates or breakdown products (metabolites) of various coffee compounds whose urine concentrations correlated strongly with the level of coffee consumption. At the time, however, the researchers had not succeeded in clearly identifying the molecular structure of the metabolites.

Use of high-performance analytical technologies

Therefore, as part of a pilot study, Roman Lang’s team examined the urine samples of six people after they had consumed 400 ml of coffee three hours earlier. With the help of high-performance analytical technologies and self-produced reference substances, the team succeeded in identifying three candidate biomarkers in the urine and, for the first time, in clearly determining their chemical structure. These are a glucuronic acid conjugate of atractyligenin, whose glycosides are present in relatively high concentrations in coffee beverages, and two glucuronic acid derivatives of an atractyligenin oxidation product.

“Our findings help advance biomarker research,” says Roman Lang. Dose-response studies, pharmacokinetics and human studies with much larger numbers of subjects must now follow to test the biomarker suitability of the identified compounds, he adds. Veronika Somoza, director of the Freising-based Leibniz Institute adds, “Food-specific biomarkers are important tools to explore the health effects of food. Therefore, part of our scientific work at LSB is also focused on finding biomarkers for food consumption.”

More information: Roman Lang et al, Metabolites of dietary atractyligenin glucoside in coffee drinkers’ urine, Food Chemistry (2022). DOI: 10.1016/j.foodchem.2022.135026

Journal information: Food Chemistry 

Provided by Leibniz-Institut für Lebensmittel-Systembiologie

Carbon-based electrocatalysts are considered as promising alternatives to the state-of-the-art precious metal catalysts. Heteroatom doping can effectively create highly active catalytic centers, but unfortunately, result in lower electronic conductivity and thus hinder the electrocatalysis process.

To address this issue, a team from South China University of Technology developed a Janus carbon electrocatalyst with different heteroatom doping levels between the two sides, which could resolve the conflict between intrinsic activity and electronic conductivity to boost the performance in the electrocatalytic hydrazine oxidation reactions.

Electrocatalysis enables the transformation of electrical energy to chemical energy. The smooth proceeding of electrocatalytic reactions relies on the design of electrocatalysts with highly active centers and efficient electron conduction. Carbon materials represent an important class of electrocatalysts. The major barrier to performance improvement of carbon materials is the trade-off between intrinsic activity and electronic conductivity.

Now, a team led by Prof. Yingwei Li at South China University of Technology addressed this issue by developing a carbon-based catalyst with a Janus structure. The Janus carbon electrocatalyst consists of a conductive nitrogen-doped carbon block (NC) and catalytically active boron-, nitrogen co-doped carbon nanosheets (BNC).

“The design of Janus carbon nanomaterials is not an easy task. Carbon materials are usually prepared by the carbonization of carbon-containing precursors. However, conventional precursors lack the designability to synthesize carbon materials with tunable structures and compositions. Our group has been engaged in the development of efficient catalysts based on metal-organic frameworks (MOFs), a class of materials with high designability, tunable compositions, and ordered atomic distributions. The interesting properties of MOFs motivated us to design a Janus MOF as the precursor for Janus carbon nanomaterials,” explained Yingwei Li.

The researchers developed a “molecular clipping and re-suturing” strategy for the construction of the Janus MOF. ZIF-8 crystals were heated in a methanol solution of boric acid. ZIF-8 was slowly etched by boric acid to release metal ions and ligands, followed by nucleation and growth of B-MOF on etched ZIF-8. ZIF-8/B-MOF was then employed as precursors for the synthesis of Janus NC/BNC.

The NC side displayed a lower doping level and thus a higher electronic conductivity compared with the BNC side. However, the BNC side possessed catalytically active BO₃ sites with higher intrinsic activity. The integration of NC with BNC could not only ensure high electronic conductivity of the hybrid, but also induce further charge delocalization of active sites on the BNC side with enhanced catalytic activity.

In the electrocatalytic hydrazine oxidation reaction, NC/BNC exhibited significantly improved activity than the single counterparts and simple physical mixtures.

In view of the big family of MOFs, the team believes that the proposed MOF-templated strategy can be extended to the synthesis of various Janus carbon materials with tunable compositions and structures. This will hopefully enrich the toolbox of tailorable chemistry and nanotechnology for potential applications in interfacial stabilizers, drug delivery, and phase-transfer catalysis.

The research is published in the journal National Science Review.

More information: Jieting Ding et al, A Janus heteroatom-doped carbon electrocatalyst for hydrazine oxidation, National Science Review (2022). DOI: 10.1093/nsr/nwac231

Provided by Science China Press 

When winter chill strikes, people stay indoors more often, giving airborne pathogens—such as SARS-CoV-2 and influenza—prime opportunities to spread. Germicidal ultraviolet (GUV) lamps can help disinfect circulating air, but their UVC wavelengths could also transform airborne compounds into potentially harmful substances.

Now, researchers reporting in Environmental Science & Technology Letters have modeled the reactions initiated by UVC sanitizing light and find that there’s a trade-off between removing viruses and producing air pollutants.

Disinfecting UVC, also called germicidal UV, lamp systems have long been a cost-effective way to rapidly inactivate airborne pathogens indoors. One design uses lamps that shine at 254 nm, a wavelength that’s damaging to humans’ skin and eyes, requiring the devices to be mounted near the ceiling or inside ventilation ducts. Recently, light at 222 nm has been suggested for whole-room disinfection because the wavelength is reported to be safer for humans.

However, UVC light can set off many reactions. For example, this type of light is known to break apart molecules in the air, forming strong oxidants, such as hydroxyl radicals and ozone. Then these oxidants can convert volatile organic compounds (VOCs) already in the air into peroxides and carbonyl compounds, which can be further broken up by UVC light into organic radicals.

The strong oxidants and organic radicals are known to undergo secondary reactions to generate additional VOCs and particulate matter, some of which could negatively impact people’s health. But the levels of compounds potentially generated from these secondary reactions from GUV systems hadn’t been studied. So, Zhe Peng, Shelly Miller and Jose Jimenez wanted to use computer models to evaluate the possible impact that the two types of UVC air cleaning systems could have on disinfection and air quality in typical indoor conditions.

With computer simulations, the researchers estimated the SARS-CoV-2 virus removal rate and the amount of secondary VOCs that would be generated in three indoor scenarios in conjunction with different room ventilation rates. Initial results indicated that both UVC wavelengths would significantly decrease the risk of infection by SARS-CoV-2 compared to ventilation alone.

The models also projected that the systems would initiate secondary reactions with VOCs expected to be in indoor air. Although only small amounts of secondary VOCs, ozone and particulate matter would likely be produced, the estimated levels weren’t negligible.

Based on the results, the team recommends the use of GUV systems in environments at high risk of airborne pathogen transmission—those in which the benefit of removing these microbes outweighs the impact of the added air pollutants. The researchers point out, however, that this study’s findings are limited to the conditions chosen for the computer models, which could be different in real-world locations.

More information: Zhe Peng et al, Model Evaluation of Secondary Chemistry due to Disinfection of Indoor Air with Germicidal Ultraviolet Lamps, Environmental Science & Technology Letters (2022). DOI: 10.1021/acs.estlett.2c00599

Journal information: Environmental Science & Technology Letters 

Provided by American Chemical Society 

Numerous plastics are principally biodegradable, but are only degraded very slowly in the open air, wastewater, or composting plants. Known enzymes with the ability to degrade plastics could solve this problem.

To do so, however, they must be able to withstand high temperatures. An interdisciplinary team from the Collaborative Research Center “Microplastics” at the University of Bayreuth has now presented new methods in the journal Biomacromolecules that are a crucial prerequisite for protecting enzymes from high heat. If enzymes are thermally stable, they can be added to biodegradable plastics during production and later accelerate natural degradation.

In principle, natural plastic degradation in the environment could be accelerated with the help of enzymes. For example, the enzyme proteinase K is capable of attacking and breaking down PLLA molecules. This ability of certain enzymes to degrade plastics could be optimally exploited if it were possible to equip biodegradable plastics with these enzymes during their production.

The enzymes would then later become active in the environment, in wastewater, or composting plants. However, precisely this attractive solution to the problem has so far been prevented by the fact that melt extrusion is used in the industrial production of aliphatic polyesters and other biodegradable plastics.

This is an indispensable production step that takes place at very high temperatures of well over 100 degrees Celsius. Until now, no way has been found to protect enzymes well enough to keep them stable at high heat and thereby preserve essential functions such as the ability to degrade plastics. There was a lack of scientific methods that could be used to obtain precise data on the heat resistance of enzymes.

At this point, the interdisciplinary team of the Bayreuth Collaborative Research Center 1537 “Microplastics” has now made decisive progress. In collaboration with the Federal Institute for Materials Research and Testing (BAM), the scientists have developed quantitative methods using proteinase K as an example, which allow the thermal stability of enzymes to be determined with a previously unattained level of detail—up to a temperature of 200 degrees Celsius.

“With the methods we present in our new study, it will be possible to preserve enzymes from thermal decomposition much better than before. We now have a reliable tool in hand to evaluate technical measures developed and proposed to protect enzymes in terms of their effectiveness,” says the study’s first author Chengzhang Xu, a doctoral student at the Chair of Macromolecular Chemistry II at the University of Bayreuth.

She already has her sights set on further research steps: “In Bayreuth, we intend to explore new methods for heat-resistant encapsulation of proteinase K. Encapsulation seems to be a promising way to introduce enzymes into the production of biodegradable plastics.”

“The research results we have achieved using proteinase K as an example are potentially transferable to other proteins. They thus strengthen a still young research direction that is developing new hybrid materials based on enzymatically degradable plastics that can be deformed under heat. These materials not only serve to combat microplastic waste, but can also support the development of new drugs or the regeneration of diseased or damaged tissue, for example,” says Prof. Dr. Andreas Greiner, holder of the Chair of Macromolecular Chemistry II, who coordinated the research work.

More information: Chengzhang Xu et al, Investigation of the Thermal Stability of Proteinase K for the Melt Processing of Poly(l-lactide), Biomacromolecules (2022). DOI: 10.1021/acs.biomac.2c01008

Journal information: Biomacromolecules 

Provided by University of Bayreuth 

In recent years, research and development on quantum computers has made considerable progress. Quantum chemical calculations for electronic structures of atoms and molecules are attracting great attention as one of the most promising applications for quantum computers. In order to utilize quantum chemical calculations for chemistry and related fields, it is essential to develop geometry optimization methods to find the most stable structure for molecules. Geometry optimization requires calculations of energy derivatives with respect to nuclear coordinates of molecules.

The finite difference method is one approach for energy derivative calculations. On a classical computer, calculations based on this method for one-dimensional systems require at least two evaluations of the energy. Previous research has shown that a quantum computer, in contrast, requires only a single query to calculate the energy derivatives based on the finite difference method, regardless of the number of degrees of freedom. However, quantum circuits relevant to quantum algorithms capable of performing energy derivative calculations have not been implemented.

A research group including Dr. Kenji Sugisaki, Professor Kazunobu Sato, and Professor Emeritus Takeji Takui from the Graduate School of Science at Osaka Metropolitan University has successfully extended the quantum phase difference estimation algorithm, a general quantum algorithm for the direct calculations of energy gaps, to enable the direct calculation of energy differences between two different molecular geometries. This allows for the computation, based on the finite difference method, of energy derivatives with respect to nuclear coordinates in a single calculation.

Furthermore, the research group has applied the developed energy derivative calculations to execute geometry optimizations of H₂, LiH, BeH₂, and N₂ molecules without calculating the total energies, demonstrating the usefulness of the developed method. The group also discussed how quantum circuits can be assembled according to different degrees of freedom of the molecules.

This research is the latest in a series of the researchers’ articles on quantum chemical calculations on quantum computers. “Our latest findings bring us one step closer to applying quantum chemical calculations on a quantum computer to real-world problems,” said Dr. Sugisaki.

“Since energy derivative calculations are used for not only molecular geometry optimizations but also various calculations for molecular properties, the application of our method is expected to play a very important role in a wide range of related fields, such as in silico drug discovery/design and materials development.”

The study is published in The Journal of Physical Chemistry Letters.

More information: Quantum Algorithm for Numerical Energy Gradient Calculations at the Full Configuration Interaction Level of Theory, The Journal of Physical Chemistry Letters (2022). DOI: 10.1021/acs.jpclett.2c02737

Journal information: Journal of Physical Chemistry Letters 

Provided by Osaka Metropolitan University