Comment

Comment by Dr. Krishna Kumari Challa on November 12, 2022 at 11:09am

Nanocrystals store light energy and drive chemical reactions

Chemistry is increasingly making use of the trick plants can do with photosynthesis: driving chemical reactions that run poorly or do not occur spontaneously at all with light energy. This requires suitable photocatalysts that capture light energy and make it available for the reaction. In the journal Angewandte Chemie, a  research team has now introduced layered core/shell quantum dots that efficiently drive challenging organic transformations. Their low toxicity is a particular advantage.

Quantum dots are finely dispersed nanoscopic crystals of inorganic semiconductors. They absorb strongly in an adjustable range of the spectrum and are easy to recycle. Until now, photocatalytic quantum dots have been based almost exclusively on the highly toxic elements cadmium and lead. This and their limited efficiency have been the main barriers to their broader use.

A research team  has now introduced novel quantum dots with very low toxicity and very high performance. They are activated by commercially available blue LEDs—the UV light that is usually required is not needed. The secret to their success lies in their core/shell structure and the variable coatings that can be used to "store" the light energy.

The quantum dots are only a few nanometers wide. Their core consists of zinc selenide (ZnSe) and is surrounded by a thin shell made of zinc sulfide (ZnS). Blue light raises the zinc selenide to an excited state in which it can easily give up electrons. The shell prevents the electrons from immediately being captured by so-called defects. The team equipped the surface of the shell with special benzophenone ligands that "suck up" the electrons from the quantum dots, store them, and make them available for organic reactions. For example, the team was able to carry out reductive dehalogenations of aryl chlorides and additive-free polymerizations of acrylates—important reactions that run poorly or not at all by conventional photocatalysts. A second version was made by coating the surface with biphenyl ligands that can directly absorb energy from excited quantum dots. This brings them into a long-lived, highly energetic triplet state. The triplet energy "stored" in this way can be transferred to specific organic molecules, which then also enter a triplet state. In this state, they can undergo chemical reactions that are not possible in their ground state. As a demonstration, the team carried out [2+2] homo-cycloadditions of styrene and cycloadditions of carbonyls with alkenes. These produce four-membered rings (cyclobutanes or oxetanes, respectively), which are substances that are important starting materials in areas such as pharmaceutical development.

 Chengming Nie et al, Low‐Toxicity ZnSe/ZnS Quantum Dots as Potent Photoreductants and Triplet Sensitizers for Organic Transformations, Angewandte Chemie International Edition (2022). DOI: 10.1002/anie.202213065

Comment by Dr. Krishna Kumari Challa on November 12, 2022 at 11:06am

Nanocrystals store light energy and drive chemical reactions

Chemistry is increasingly making use of the trick plants can do with photosynthesis: driving chemical reactions that run poorly or do not occur spontaneously at all with light energy. This requires suitable photocatalysts that capture light energy and make it available for the reaction. In the journal Angewandte Chemie, a Chinese research team has now introduced layered core/shell quantum dots that efficiently drive challenging organic transformations. Their low toxicity is a particular advantage.

Comment by Dr. Krishna Kumari Challa on November 12, 2022 at 10:30am

A microscopic video shows a virus (purple track) as it finds its way to the surface of human intestinal cells (green).

Researchers have captured the first real-time footage of viruses on the move, right before they hijack a cell.

Comment by Dr. Krishna Kumari Challa on November 12, 2022 at 10:22am

CRISPR cancer trial success paves the way for personalized treatments

‘Most complicated therapy ever’ tailors bespoke, genome-edited immune cells to attack tumours.

A small clinical trial has shown that researchers can use CRISPR gene editing to alter immune cells so that they will recognize mutated proteins specific to a person’s tumours. Those cells can then be safely set loose in the body to find and destroy their target.

It is the first attempt to combine two hot areas in cancer research: gene editing to create personalized treatments, and engineering immune cells called T cells so as to better target tumours. The approach was tested in 16 people with solid tumours, including in the breast and colon.

Foy, S. P. et al. Nature https://doi.org/10.1038/s41586-022-05531-1 (2022).

https://www.nature.com/articles/d41586-022-03676-7?utm_source=Natur...

Comment by Dr. Krishna Kumari Challa on November 12, 2022 at 10:21am

‘Most complicated therapy ever’ success

A small clinical trial has shown that CRISPR gene editing can alter immune cells so that they seek out an.... T cells, a type of white blood cell that patrols the body looking for errant cells, were modified to recognize the mutated proteins in tumours, which are different in every person. It is the first attempt to combine two hot areas of cancer research: gene editing to create personalized treatments, and the engineering of T cells to make them better at targeting tumours. “It is probably the most complicated therapy ever attempted in the clinic,” says study co-author Antoni Ribas, a cancer researcher and physician. “We’re trying to make an army out of a patient’s own T cells.”

Comment by Dr. Krishna Kumari Challa on November 11, 2022 at 8:03am

Rare, deadly genetic disease successfully treated in utero for first time

Physicians have successfully treated a fetus with a devastating genetic disorder for the first time, and the child is now thriving as a toddler, a case study in the New England Journal of Medicine reports.

This treatment expands the repertoire of fetal therapies in a new direction. As new treatments become available for children with genetic conditions, researchers and doctors are developing protocols to apply them before birth.

The child's disorder, infantile-onset Pompe disease, is one of several lysosomal storage diseases that begin to cause severe damage to major organs, such as the heart, before birth. By initiating enzyme replacement therapy during fetal development, physicians aimed for better outcomes than are typical with post-birth treatment—outcomes that can include death in early childhood, very low muscle tone or ventilator dependency.

After six prenatal enzyme replacement treatments at The Ottawa Hospital, the child, Ayla, was born at term. She is receiving postnatal enzyme therapy at CHEO (a pediatric hospital and research center in Ottawa, Canada), and doing well at 16 months of age. She has normal cardiac and motor function and is meeting developmental milestones.

The successful treatment is a feat of collaboration between UCSF, where an ongoing clinical trial on the treatment is based; CHEO and The Ottawa Hospital, where the patient was diagnosed and treated; and Duke University, home to the world's top experts on Pompe disease.  

Jennifer L. Cohen et al, In Utero Enzyme-Replacement Therapy for Infantile-Onset Pompe's Disease, New England Journal of Medicine (2022). 10.1056/NEJMoa2200587. www.nejm.org/doi/full/10.1056/NEJMoa2200587

Comment by Dr. Krishna Kumari Challa on November 11, 2022 at 7:55am

Scientists identify neurons that restore walking after paralysis

A new study by scientists at the .NeuroRestore research center has identified the type of neuron that is activated and remodeled by spinal cord stimulation, allowing patients to stand up, walk and rebuild their muscles – thus improving their quality of life. This discovery, made in nine patients, marks a fundamental, clinical breakthrough. The study was published in Nature on Nov 9, 2022.

Comment by Dr. Krishna Kumari Challa on November 10, 2022 at 11:25am

Starved yeast poisons clones

Yeast is not the simple single-celled microorganism we once thought, but a competitive killer. When starved of glucose, yeast releases a toxin that will poison other microorganisms that have entered its surrounding habitat, even its own clones. This venomous phenomenon was previously unknown and contributes to our understanding of unicellular microorganism behavior, the evolution of unicellular to multicellular organisms, as well as having potentially useful applications for the food industry.

In the critical survival situation of glucose starvation, yeasts release toxins into their habitat which kill other microorganisms while the yeast itself acquires resistance.

 The toxins produced by yeasts can also kill their nonadapted clones, so they are at risk of killing not only invading microorganisms but also their own offspring. Such seemingly risky and almost suicidal behavior had not previously been found in a single-celled organism or even considered to exist.

Although cooperative forms of behavior are well known in many bacteria and fungi, this research is the first prominent finding of competitiveness occurring in clonal cells in unicellular organisms. This has important implications for our understanding of the ecology of microorganisms, as well as why some specific microorganisms grow during fermentation while others do not. 

Arisa H. Oda, Miki Tamura, Kunihiko Kaneko, Kunihiro Ohta, Tetsuhiro S. Hatakeyama. Autotoxin-mediated latecomer killing in yeast communities. PLOS Biology, 2022; 20 (11): e3001844 DOI: 10.1371/journal.pbio.3001844

Comment by Dr. Krishna Kumari Challa on November 10, 2022 at 11:15am

A new nanoparticle to act at the heart of cells

How can a drug be delivered exactly where it is needed, while limiting the risk of side effects? The use of nanoparticles to encapsulate a drug to protect it and the body until it reaches its point of action is being increasingly studied. However, this requires identifying the right nanoparticle for each drug according to a series of precise parameters.

--

Physical theory describes movements of micro-hairs

They are only very simple structures, but without them we could not survive: Countless tiny hairs (cilia) are found on the outer wall of some cells, for example in our lungs or in our brain. When these micrometer-sized hairs coordinate their movement and produce wave-like movements together, they can cause currents on a microscale and thus pump fluid from one place to another. Paramecia—unicellular organisms with numerous cilia—also use such effects to move around.

--

Greenwashing: ‘the sham must end’

A United Nations-backed report has called out businesses and financial institutions whose net-zero commitments have “loopholes wide enough to drive a diesel truck through”. The group points to those who continue to invest in fossil fuels, offset emissions with shoddy ca... to undermine ambitious government climate policies. It also calls for public reporting and regulation to ensure companies are doing what they claim. "We must have zero tolerance for net-zero greenwashing,” said UN secretary-general António Guterres. “The sham must end.”

Comment by Dr. Krishna Kumari Challa on November 10, 2022 at 10:10am

Fertilizers limit pollination by changing how bumblebees sense flowers

Pollinators are less likely to land on flowers sprayed with fertilizers or pesticides as they can detect electric field changes around the flower, researchers have found.

The study, published in PNAS Nexus recently, shows that chemical sprays alter the electric field around flowers for up to 25 minutes after exposure. This impact lasts substantially longer than natural fluctuations, such as those caused by wind, and causes a reduction in bee feeding effort in nature.

The researchers  noted that fertilizers did not affect vision and smell, and set out to mimic the electrical changes caused by fertilizers and pesticides in the field by electrically manipulating flowers. This showed that bumblebees were able to detect and discriminate against the small and dynamic electric field alterations that are caused by the chemicals.

Flowers have a range of cues that attract bees to promote feeding and pollination. For instance, bees use cues like flower odor and color, but they also use electric fields to identify plants.

A big issue is thus—agrochemical application can distort floral cues and modify behavior in pollinators like bees.

Furthermore, various other airborne particles such as nanoparticles, exhaust gases, nano-plastics, and viral particles may have similar impacts, affecting a wide array of organisms that use the electric fields that are virtually everywhere in the environment.

It's the first known example of anthropogenic 'noise' interfering with a terrestrial animal's electrical sense. It's much like motorboat noise that hinders the ability of fish to detect their predators, or artificial light at night that confuses moths; the fertilizers are a source of noise to bees trying to detect floral electrical cues.

This widens our understanding of the multifaceted ways in which human activity is negatively impacting the natural world. 

Synthetic fertilizers alter floral biophysical cues and bumblebee foraging behavior, PNAS Nexus (2022). DOI: 10.1093/pnasnexus/pgac230. academic.oup.com/pnasnexus/art … 93/pnasnexus/pgac230

• ‹ Previous
• 1
• …
• 210
• 211
• 212
• 213
• 214
• …
• 839
• Next ›
• Page