. Scientific Frontline: Chemistry
Showing posts with label Chemistry. Show all posts
Showing posts with label Chemistry. Show all posts

Friday, February 3, 2023

Robots and A.I. team up to discover highly selective catalysts

Close up of the semi-automated synthesis robot used to generate training data
Photo Credit: ICReDD

Researchers used a chemical synthesis robot and computationally cost effective A.I. model to successfully predict and validate highly selective catalysts.

Artificial intelligence (A.I.) has made headlines recently with the advent of ChatGPT’s language processing capabilities. Creating a similarly powerful tool for chemical reaction design remains a significant challenge, especially for complex catalytic reactions. To help address this challenge, researchers at the Institute for Chemical Reaction Design and Discovery and the Max Planck Institut für Kohlenforschung have demonstrated a machine learning method that utilizes advanced yet efficient 2D chemical descriptors to accurately predict highly selective asymmetric catalysts—without the need for quantum chemical computations.  

“There have been several advanced technologies which can “predict” catalyst structures, but those methods often required large investments of calculation resources and time; yet their accuracy was still limited,” said joint first author Nobuya Tsuji. “In this project, we have developed a predictive model which you can run even with an everyday laptop PC.”

Thursday, February 2, 2023

Molecular machines could treat fungal infections

Schematic representation of the mechanisms by which light-activated molecular machines kill fungi. Molecular machines bind to fungal mitochondria, decreasing adenosine triphosphate (ATP) production and impairing the function of energy-dependent transporters that control the movement of ions, such as calcium. This leads to the influx of water, which causes the organelles to swell and eventually the cells to burst.
Image Credit: Tour Group/Rice University

That stubborn athlete’s foot infection an estimated 70% of people get at some point in their life could become much easier to get rid of thanks to nanoscale drills activated by visible light.

Proven effective against antibiotic-resistant infectious bacteria and cancer cells, the molecular machines developed by Rice University chemist James Tour and collaborators are just as good at combating infectious fungi, according to a new study published in Advanced Science.

Based on the work of Nobel laureate Bernard Feringa, the Tour group’s molecular machines are nanoscale compounds whose paddlelike chain of atoms moves in a single direction when exposed to visible light. This causes a drilling motion that allows the machines to bore into the surface of cells, killing them.

Reading out RNA structures in real time

The fluorescent blinking of cyanine dye (Alexa Fluor 647, pink star) bound to RNA changes depending on the structure of the RNA. When the RNA is folded like a hairpin, the fluorescent blinking is fast, and when the RNA switches to a G-quadruplex, the blinking is slow
Illustration Credit: Akira Kitamura

A new microscopic technique allows for the real-time study of RNA G-quadruplexes in living cells, with implications for the fight against amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS), commonly known as Lou Gehrig’s disease and Stephen Hawking’s disease, is a neurodegenerative disease that results in the gradual loss of control over the muscles in the body. It is currently incurable and the cause of the disease is unknown in over 90% of all cases — although both genetic and environmental factors are believed to be involved.

The research groups of Dr. Akira Kitamura at the Faculty of Advanced Life Science, Hokkaido University, and Prof. Jerker Widengren at the KTH Royal Institute of Technology, Sweden, have developed a novel technique that is able to detect a characteristic structure of RNA in real time in live cells. The technique, which is based on fluorescence-microscopic spectroscopy, was published in the journal Nucleic Acids Research.

Wednesday, February 1, 2023

Solid material that 'upconverts' visible light photons to UV light photons could change how we utilize sunlight

Low-intensity visible blue light or lower energy photons being converted into higher energy UV photons using a solid film formed on a round glass substrate, developed by researchers at Tokyo Tech
 Image Credit: Prof. Yoichi Murakami

Ultraviolet (UV) light has higher energy photons than visible light and, thus, has more applications. Tokyo Tech researchers have now developed a brilliant innovation—a solid-state material that can stably and efficiently upconvert sunlight- intensity visible light photons to UV light photons. This photon upconversion (UC) material can utilize visible light to successfully drive reactions that would conventionally need UV light, broadening the spectrum of utility for the former.

The importance of solar power as a renewable energy resource is increasing. Sunlight contains high-energy UV light with a wavelength shorter than 400 nm, which can be broadly used, for example, for photopolymerization to form a resin and activation of photocatalysts to drive reactions that generate green hydrogen or useful hydrocarbons (fuels, sugars, olefins, etc.). The latter of these is often called "artificial photosynthesis." Photocatalytic reaction by UV light to efficiently kill viruses and bacteria is another important application. Unfortunately, only about 4% of terrestrial sunlight falls within the UV range in the electromagnetic spectrum. This leaves a large portion of sunlight spectrum unexploited for these purposes.

Monday, January 30, 2023

RUDN University Chemists Create Substances for Supramolecules Self-assembly

Illustration Credit: RUDN University

RUDN University chemists derived molecules that can assemble into complex structures using chlorine and bromine halogen atoms. They bind to each other as “Velcro” — chlorine “sticks” to bromine, and vice versa. As a result, supramolecules are assembled from individual molecules. The obtained substances will help to create supramolecules with catalytic, luminescent, conducting properties.

Supramolecules are the structures made of several molecules. Individual molecules are combined, for example, by self-assembly or without external control. The resulting structure has properties that the molecules did not have individually. That is the way to create new materials, catalysts, molecular machines for drug delivery, conductors, and so on. To get a material with the specified properties, you need to choose the right starting molecules and auxiliary substances that will ensure their unification. One of the ways to control self-assembly is halogen-halogen interactions. These are the chemical bonds forming between two halogens (for example, chlorine, fluorine, bromine). RUDN University chemists have created a molecule with a halogen bond that can form supramolecules by itself or provide the required self-assembly with other substances. They will help to create substances for the chemical industry, medicine, and electronics.

Friday, January 27, 2023

Targeting cancer with a multidrug nanoparticle

MIT chemists designed a bottlebrush-shaped nanoparticle that can be loaded with multiple drugs, in ratios that can be easily controlled.
Illustration Credit: Courtesy of the researchers. Edited by MIT News.

Treating cancer with combinations of drugs can be more effective than using a single drug. However, figuring out the optimal combination of drugs, and making sure that all of the drugs reach the right place, can be challenging.

To help address those challenges, MIT chemists have designed a bottlebrush-shaped nanoparticle that can be loaded with multiple drugs, in ratios that can be easily controlled. Using these particles, the researchers were able to calculate and then deliver the optimal ratio of three cancer drugs used to treat multiple myeloma.

“There’s a lot of interest in finding synergistic combination therapies for cancer, meaning that they leverage some underlying mechanism of the cancer cell that allows them to kill more effectively, but oftentimes we don’t know what that right ratio will be,” says Jeremiah Johnson, an MIT professor of chemistry and one of the senior authors of the study.

Thursday, January 26, 2023

Mimicking an Enigmatic Property of Circadian Rhythms through an Artificial Chemical Clock

An innovative temperature-compensation mechanism for oscillating chemical reactions based on temperature-responsive gels has been recently reported by researchers at Tokyo Tech. Their experimental findings, alongside a detailed mathematical analysis, hint at the possibility that circadian rhythms found in nature may all rely on a similar mechanism, allowing their period to remain independent of temperature.

Circadian rhythms are natural, internal oscillations that synchronize an organism's behaviors and physiological processes with their environment. These rhythms normally have a period of 24 hours and are regulated by internal chemical clocks that respond to cues from outside the body, such as light.

Although well studied in animals, plants, and bacteria, circadian rhythms all share an enigmatic property—the oscillation period is not significantly affected by temperature, even though the rate of most biochemical reactions changes exponentially with temperature. This clearly indicates that some sort of temperature-compensation mechanism is at play. Interestingly, some scientists have managed to replicate such temperature-invariant qualities in certain oscillating chemical reactions. However, these reactions are often troublesome and require extremely precise adjustments on the reacting chemicals.

Wednesday, January 25, 2023

Artificial photosynthesis uses sunlight to make biodegradable plastic

Fumaric acid synthesis from CO2 using solar energy. Using sunlight to power the photoredox system pyruvic acid and CO2 are converted into fumaric acid, by malate dehydrogenase and fumarase.
Illustration Credit: Yutaka Amao, Osaka Metropolitan University

In recent years, environmental problems caused by global warming have become more apparent due to greenhouse gases such as CO2. In natural photosynthesis, CO2 is not reduced directly, but is bound to organic compounds which are converted to glucose or starch. Mimicking this, artificial photosynthesis could reduce CO2 by combining it into organic compounds to be used as raw materials, which can be converted into durable forms such as plastic.

A research team led by Professor Yutaka Amao from the Research Center for Artificial Photosynthesis and graduate student Mika Takeuchi, from the Osaka Metropolitan University Graduate School of Science, have succeeded in synthesizing fumaric acid from CO2, a raw material for plastics, powered—for the first time—by sunlight. Their findings were published in Sustainable Energy & Fuels.

Tuesday, January 24, 2023

New enzyme could mean better drugs

A scientist works in the lab of Rice’s Xue Sherry Gao.
Photo Credit: Jeff Fitlow/Rice University

Just as a choreographer’s notation tells a dancer to strike a particular pose, an enzyme newly discovered by Rice University scientists is able to tell specific molecules precisely how to arrange themselves, down to the angle of single hydrogen bonds.

Biomolecular engineers at Rice identified a new Diels-Alderase (DAase), an enzyme that catalyzes the Diels-Alder reaction, a widely used method of synthesizing important materials and pharmaceuticals, from raw materials for plastics and fuels to synthetic steroids.

The enzyme, known as CtdP, was previously thought to be a different type of protein — a “regulator” controlling gene expression. Regulators typically do not serve a catalytic function, meaning they cannot “transform compound A into compound B,” said study co-author Xue Sherry Gao.

Mirror Image: FSU study lays out chirality flipping theory

Ken Hanson, left, and Eugene DePrince, right, are faculty members in the Department of Chemistry and Biochemistry.
Photo Credit: Florida State University

Chemists can make a career out of controlling whether certain molecules are generated as a lefty or a righty.

Molecules don’t literally have hands, but scientists often refer to them in this way when looking at molecules that are mirror images of each other and therefore are not superimposable. And whether a molecule is a lefty or a righty directly affects how they behave and their use in everything from drug design to flavoring foods.

A Florida State University research team led by Associate Professor of Chemistry Ken Hanson previously found a way to turn “left-handed” molecules into “right-handed” ones by using light to induce a proton transfer and the transformation into a different isomer. Now, Hanson and his fellow FSU Professor of Chemistry Eugene DePrince are harnessing the power of math and computers to predict what would happen if you performed that same process in a gap between closely spaced mirrors.

Monday, January 23, 2023

Scientists Unveil Least Costly Carbon Capture System to Date

Chemist Dave Heldebrant, a recently selected fellow of the American Chemical Society who holds a joint appointment with Washington State University, has helped design several solvents that can deftly capture carbon dioxide molecules before they reach Earth’s atmosphere. 
Photo Credit: Andrea Starr | Pacific Northwest National Laboratory

The need for technology that can capture, remove and repurpose carbon dioxide grows stronger with every CO2 molecule that reaches Earth’s atmosphere. To meet that need, scientists at the Department of Energy’s Pacific Northwest National Laboratory have cleared a new milestone in their efforts to make carbon capture more affordable and widespread. They have created a new system that efficiently captures CO2—the least costly to date—and converts it into one of the world’s most widely used chemicals: methanol.

Snaring CO2 before it floats into the atmosphere is a key component in slowing global warming. Creating incentives for the largest emitters to adopt carbon capture technology, however, is an important precursor. The high cost of commercial capture technology is a longstanding barrier to its widespread use.

PNNL scientists believe methanol can provide that incentive. It has many uses as a fuel, solvent, and an important ingredient in plastics, paint, construction materials and car parts. Converting CO2 into useful substances like methanol offers a path for industrial entities to capture and repurpose their carbon.

A Rainbow of Force-Activated Pigments

A time-elapse video showing how color develops in areas of a specialized polymer that have been placed under strain.
Video Credit: Peter Holderness/Caltech

Stress isn't just the psychological pressure you feel in response to a looming deadline at work. It is also a description of the physical forces pushing, pulling, or twisting an object, structure, or material. Examples of stress include gravity dragging downward on a bridge, wind blowing against the side of a building, or even a waistband drawn taut by a big meal.

With stress affecting literally everything made and used by people, often in damaging ways, it is important to identify when and where it is happening and the extent to which it is occurring. This is not always easy, though, because many materials show no obvious signs of being under stress.

Caltech's Maxwell Robb, an assistant professor of chemistry, has been working to make stress easier to identify through the creation of polymers that change color when a force is applied to them. Now, in a paper published in Nature Chemistry, Robb shows how his team created a new type of these polymers that can be made to change to almost any colors the user wants. This is in contrast to the polymers he had previously developed, which could only change to a single, predetermined color.

Friday, January 20, 2023

RUDN University chemist creates nanocatalysts for vanillin synthesis

Illustration Credit: RUDN University

RUDN University chemist proposed a new method to create catalysts on a porous silicon matrix with metal nanoparticles. Efficient catalysts for organic reactions are obtained, for example, for the synthesis of vanillin, which is in demand in the food and perfume industry.

Only 1% of the annually produced worldwide 20 thousand tons of vanillin is made from natural vanilla. Almost all vanillin in seasonings, pastries, pharmaceuticals and cosmetics is synthesized by chemical protocols. Usually, petrochemical raw materials are used for this, but synthesis from inexpensive plant biomass is also possible. The main ingredient is lignin. This polymer is widely available as it is part of the trees, and it is obtained in the production of paper as a by-product. It is easy to isolate eugenol and other substances suitable for the synthesis of vanillin from lignin, but the next step is challenging. In oxidation reactions, along with vanillin, several by-products similar to it in structure are formed. It is difficult to separate them. The RUDN University chemist proposed a number of eco-friendly nanocatalysts that will allow obtaining more vanillin from plant raw materials than traditional methods.

Algae Can Help Dispose of Hazardous Substances and Produce Bioethanol

Algae can absorb zinc, magnesium, iron, aluminum, silicon and lead.
Photo Credit: Rodion Narudinov

Scientists of the Ural Federal University have developed a technology for the production of environmentally friendly bioethanol fuel using waste heat from thermal power plants (TPP) and combined heat and power plants (CHPP) and freshwater algae produced in large quantities in cooling ponds. The use of this technology leads to a reduction in harmful emissions and makes energy production more efficient. The developers emphasize that the technology signifies a transition from hydrocarbon to green energy. An article describing the technology has been published in the International Journal of Hydrogen Energy.

TPPs and CHPPs are the main suppliers of heat, light, and hot water; at the same time, they are sources of greenhouse gas emissions generated during fuel combustion and saturated with carbon dioxide, soot, unburned particles, and various chemical substances. Another byproduct is the so-called waste heat - water heated during the cooling of superheated steam, rotating turbines of TPPs and CHPPs. The waste heat, in the form of steam, evaporates into the atmosphere in large quantities and is discharged together with industrial effluents into storage ponds. Process water containing solutions of hydrochloric acid, caustic soda, ammonia, ammonium salts, iron and other substances is discharged after flushing the flue gases and boiler units.

Researchers unravel the complex reaction pathways in zero carbon fuel synthesis

Chemical plant
Photo Credit: Robert Jones

When the eCO2EP: A chemical energy storage technology project started in 2018, the objective was to develop ways of converting carbon dioxide emitted as part of industrial processes into useful compounds, a process known as electrochemical CO2 reduction (eCO2R)

While eCO2R is not a new technique, the challenge has always been the inability to control the end products. Now, researchers from the University of Cambridge have outlined how carbon isotopes can be used to trace intermediates during the process, which will allow scientists to create more selective catalysts, control product selectivity, and promote eCO2R as a more promising production method for chemicals and fuels in the low-carbon economy. Their results are reported in the journal Nature Catalysis.

The project was led by Professor Alexei Lapkin, from Cambridge’s Centre for Advanced Research and Education in Singapore (CARES Ltd) and Professor Joel Ager, from the Berkeley Education Alliance for Research in Singapore (BEARS Ltd). Both organizations are part of the Campus for Research Excellence and Technological Enterprise (CREATE) funded by Singapore’s National Research Foundation.

Magnetic method to clean PFAS contaminated water

Researchers at The University of Queensland have pioneered a simple, fast and effective technique to remove PFAS chemicals from water.  

Using a magnet and a reusable absorption aid that they developed, polymer chemist Dr Cheng Zhang and PhD candidate Xiao Tan at the Australian Institute for Bioengineering and Nanotechnology have cleared 95 per cent of per- and polyfluoroalkyl substances (PFAS) from a small amount of contaminated water in under a minute.

“Removing PFAS chemicals from contaminated waters is urgently needed to safeguard public and environmental health,” Dr Zhang said.

“But existing methods require machinery like pumps, take a lot of time and need their own power source.

“Our method shows it is possible to remove more of these chemicals in a way that is faster, cheaper, cleaner, and very simple.

Thursday, January 19, 2023

New, safe, and biodegradable compound blocks radiation

Hesham Zakali: The material developed by an international group of scientists could become an alternative to toxic lead, for example.
Photo Credit: Anastasia Kurshpel

Polylactic acid combined with tungsten trioxide effectively blocks gamma radiation, an international group of scientists including specialists from Russia (Ural Federal University), Saudi Arabia and Egypt has found. In the future, it will be possible to create safe and biodegradable screens for protection against low-energy radiation on the basis of the new material, the researchers believe. Such screens are used in medicine, agriculture and the food industry. A description of the material has been published in the journal Radiation Physics and Chemistry.

"Polylactic acid is a non-toxic polymer of natural origin. It is inexpensive and, importantly, can be broken down by microbes when placed in an industrial plant at high temperatures. Since lactic acid is regularly produced as a byproduct of metabolism in both plants and animals, polylactic acid and its degradation products are non-toxic and safe for the environment," explains Hesham Zakali, co-author of the development and Researcher at the Department of Experimental Physics at UrFU.

Wednesday, January 18, 2023

New ‘chain mail’ material of interlocking molecules is tough, flexible and easy to make

The individual building blocks of a catenane are polyhedral molecules — a type of adamantane — that link arms to form a 2D mesh or 3D network that is sturdy but flexible.
Illustration Credit: Tianqiong Ma, UC Berkeley

University of California, Berkeley, chemists have created a new type of material from millions of identical, interlocking molecules that for the first time allows the synthesis of extensive 2D or 3D structures that are flexible, strong and resilient, like the chain mail that protected medieval knights.

The material, called an infinite catenane, can be synthesized in a single chemical step.

French chemist Jean-Pierre Sauvage shared the 2016 Nobel Prize in Chemistry for synthesizing the first catenane — two linked rings. These structures served as the foundation for making molecular structures capable of moving, which are often referred to as molecular machines.

But the chemical synthesis of catenanes has remained laborious. Adding each additional ring to a catenane requires another round of chemical synthesis. In the 24 years since Sauvage created a two-ring catenane, chemists have achieved, at most, a mere 130 interwoven rings in quantities too small to see without an electron microscope.

Scientists Suggest New Approach to Targeted Treatment of Bacterial Infections

Photo Source: Ural Federal University

It is based on the nanosystem with polyoxometalate

Chemists from the Ural Federal University have proposed a new approach to targeted treatment of affected areas of the human body, in particular, bacterial infections. It is based on a nanosystem, the core of which is polyoxometalate (containing molybdenum and iron). A broad-spectrum antibiotic, tetracycline, is attached to the surface of the polyoxometalate. This approach makes it possible to fight bacteria more effectively by targeting them. The results of the study are published in the journal Inorganics.

"The polyoxometalate ion is a charged nanoparticle that can be used as a base. It is very small - 2.5 nanometers. This allows it to easily penetrate cells and the walls of blood vessels. Drugs and additional substances (vector molecules) can be "planted" on it to help the system reach a specific affected organ. In this case, the drug is distributed less throughout the rest of the body. This reduces side effects, especially of highly toxic drugs," explains Margarita Tonkushina, a Researcher at the Section of Chemical Material Science and the Laboratory of Functional Design of Nanoclusters of Polyoxometalates at UrFU.

Studying Polymer Gels Through the Lens of Mechanochemistry and Solvent Swelling

Multinetwork polymer gels with color-changing linkers sensitive to mechanical stimuli provide a solid platform to study the dynamics of solvent swelling, as shown by researchers from Tokyo Tech. This innovative approach allowed them to gain detailed insight into the mechanical forces that a gel is subjected to when swollen after absorbing a solvent. Their findings will pave the way to developing new, mechanically responsive materials for many applications.

Polymer gels have become a staple technology in various fields, ranging from optics and drug delivery to carbon capture and batteries. However, there are still many open questions about gels and their network structure, which has prevented scientists from linking their remarkable macroscopic properties to specific molecular mechanisms.

One interesting way to tackle this puzzle is to study it from the lens of mechanochemistry; that is, chemical reactions that are triggered by mechanical stimuli such as compression, stretching, and grinding. To make this process easier, scientists can weave mechanophores into polymer networks. These are molecules that undergo predictable chemical changes upon exposure to mechanical stress. While there are many ways to apply mechanical forces to activate mechanophores in a gel, one has been studied in much less detail than others: solvent swelling.

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