Tag Archives: nanoparticles

Cheap High-Performance Catalysts For Hydrogen Electric Car

The industry has been traditionally deploying platinum alloys as catalysts for oxygen reduction, which is for example essential in fuel cells or metal-air batteries. Expensive and rare, that metal imposes strict restrictions on manufacture. Researchers at Ruhr-Universität Bochum (RUB) and Max-Planck-Institut für Eisenforschung in Germany have discovered an alloy made up of five elements that is noble metal-free and as active as platinum.  The catalytic properties of non-noble elements and their alloys are usually rather poor. To the researchers’ surprise, one alloy made up of five almost equally balanced components offer much better properties. This is because of the so-called high entropy effect. It causes multinary alloys to maintain a simple crystal structure.

Through the interaction of different neighbouring elements, new active centres are formed that present entirely new properties and are therefore no longer bound to the limited properties of the individual elements,” explains Tobias Löffler, PhD student at the RUB Chair of Analytical ChemistryCenter for Electrochemical Sciences headed by Professor Wolfgang Schuhmann. “Our research has demonstrated that this alloy might be relevant for catalysis.”

Headed by Professor Christina Scheu, the research team at the Max-Planck-Institut für Eisenforschung analysed the generated nanoparticles using transmission electron microscopy. RUB chemists determined their catalytic activity and compared it with that of platinum nanoparticles. In the process, they identified a system made of up five elements where the high entropy effect results in catalytic activity for an oxygen reduction that is similar to that of platinum. By optimising the composition further, they successfully improved the overall activity.

These findings may have far-reaching consequences for electrocatalysis in general,” surmises Wolfgang Schuhmann. The researchers are hoping to adapt the properties for any required reactions by taking advantage of the almost infinite number of possible combinations of the elements and modifications of their composition. “Accordingly, the application will not necessarily be limited to oxygen reduction,” says Ludwig. The research team has already applied for a patent.

The results are published in the journal Advanced Energy Materials.

Source: http://news.rub.de/

Toxic Cocktails Of Harmful Nanoparticles

Nanoparticles, which are found in thousands of everyday products due to their unique properties, can form toxic cocktails harmful to our cells, a study has found. In a study published in the journal Nanotoxicology, scientists showed that 72 per cent of cells died after exposure to a cocktail of nano-silver and cadmium ionsNanoparticles are becoming increasingly widespread in our environment. For example, silver nanoparticles have an effective antibacterial effect and can be found in refrigerators, sports clothes, cosmetics, tooth brushes, and water filters.

There is a significant difference between how the cells react when exposed to nanosilver alone and when they are exposed to a cocktail of nanosilver and cadmium ions, which are naturally found everywhere around us on Earth, according to the researchers from University of Southern Denmark (SDU). In the study, 72 per cent of the cells died, when exposed to both nanosilver and cadmiun ions. When exposed to nanosilver only, 25 per cent died. When exposed to cadmium ions only, 12 per cent died researchers said.

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The study was conducted on human liver cancer cells. The study indicates, that we need to take cocktail effects into account when trying to ascertain their effect on our health, said Frank Kjeldsen, a professor at SDU.

Products with nano particles are being developed and manufactured every day, but in most countries there are no regulations, so there is no way of knowing what and how many nanoparticles are being released into the environment,” said Kjeldsen.

Source: https://www.sdu.dk/

Nanoparticles Destroy Dental Plaque, Prevent Tooth Decay

Combine a diet high in sugar with poor oral hygiene habits and dental cavities, or caries, will likely result. The sugar triggers the formation of an acidic biofilm, known as plaque, on the teeth, eroding the surface. Early childhood caries is a severe form of tooth decay that affects one in every four children in the United States and hundreds of millions more globally. It’s a particularly severe problem in underprivileged populations.

Treatment with a nanoparticle and hydrogen peroxide (right panel) left little in the way of bacteria (in blue) or the sticky biofilm matrix (in red), making the combination a potent force against dental plaque

In a study published in Nature Communications, researchers led by Hyun (Michel) Koo of the University of Pennsylvania School of Dental Medicine in collaboration with David Cormode of Penn’s Perelman School of Medicine and School of Engineering and Applied Science used FDA-approved nanoparticles to effectively disrupt biofilms and prevent tooth decay in both an experimental human-plaque-like biofilm and in an animal model that mimics early-childhood caries. The nanoparticles break apart dental plaque through a unique pH-activated antibiofilm mechanism.

It displays an intriguing enzyme-like property whereby the catalytic activity is dramatically enhanced at acidic pH but is ‘switched off’ at neutral pH conditions,” says Koo, professor in Penn Dental Medicine’s Department of Orthodontics. “The nanoparticles act as a peroxidase, activating hydrogen peroxide, a commonly used antiseptic, to generate free radicals that potently dismantle and kill biofilms in pathological acidic conditions but not at physiological pH, thus providing a targeted effect.”

Because the caries-causing plaque is highly acidic, the new therapy is able to precisely target areas of the teeth harboring pathogenic biofilms without harming the surrounding oral tissues or microbiota. The particular iron-containing nanoparticle used in the experiments, ferumoxytol, is already FDA-approved to treat iron-deficiency, a promising indication that a topical application of the same nanoparticle, used at several-hundred-fold lower concentration, would also be safe for human use.

Source: https://penntoday.upenn.edu/

Nano Packets Of Genetic Code Seed Cells Against Brain Cancer

In a “proof of concept” study, scientists at Johns Hopkins Medicine say they have successfully delivered nano-size packets of genetic code called microRNAs to treat human brain tumors implanted in mice. The contents of the super-small containers were designed to target cancer stem cells, a kind of cellularseed” that produces countless progeny and is a relentless barrier to ridding the brain of malignant cells.

Nanoparticles releasing microRNAs (light blue) inside a human brain cancer cell

Brain cancer is one of the most widely understood cancers in terms of its genetic makeup, but we have yet to develop a good treatment for it,” says John Laterra, MD, PhD, professor of neurology, oncology and neuroscience at the Johns Hopkins University School of Medicine and a research scientist at the Kennedy Krieger Institute. “The resilience of cancer stem cells and the blood-brain barrier are major hurdles.

Blood that enters the brain is filtered through a series of vessels that act as a protective barrier. But this blood-brain barrier blocks molecular medicines that have the potential to revolutionize brain cancer therapy by targeting cancer stem cells, says Laterra.

To modernize brain tumor treatments, we need tools and methods that bypass the blood-brain barrier,” says Jordan Green, PhD, professor of biomedical engineering, ophthalmology, oncology, neurosurgery, materials science and engineering and chemical and biomolecular engineering at the Johns Hopkins University School of Medicine. “We need technology to safely and effectively deliver sensitive genetic medicines directly to tumors without damaging normal tissue.

A case in point, Green says, is glioblastoma, the form of brain cancer that Arizona Sen. John McCain is battling, which often requires repeated surgeries. Doctors remove the brain tumor tissue that they can see, but the malignancy often returns quickly, says Laterra. Most patients with glioblastoma live less than two years after diagnosis.

Results of the experiments were published online in Nano Letters.

Source: https://engineering.jhu.edu/

Nanoparticles Fom Tea Leaves Destroy 80% Of Lung Cancer Cells

Nanoparticles derived from tea leaves inhibit the growth of lung cancer cells, destroying up to 80% of them, new research by a joint Swansea University (UK) and Indian team has shown. The team made the discovery while they were testing out a new method of producing a type of nanoparticle called quantum dots.  These are tiny particles which measure less than 10 nanometres.  A human hair is 40,000 nanometres thick.

Although nanoparticles are already used in healthcare, quantum dots have only recently attracted researchers’ attention.  Already they are showing promise for use in different applications, from computers and solar cells to tumour imaging and treating cancerQuantum dots can be made chemically, but this is complicated and expensive and has toxic side effects.  The Swansea-led research team were therefore exploring a non-toxic plant-based alternative method of producing the dots, using tea leaf extract.

Tea leaves contain a wide variety of compounds, including polyphenols, amino acids, vitamins and antioxidants.   The researchers mixed tea leaf extract with cadmium sulphate (CdSO4) and sodium sulphide (Na2S) and allowed the solution to incubate, a process which causes quantum dots to form.   They then applied the dots to lung cancer cells. Tea leaves are a simpler, cheaper and less toxic method of producing quantum dots, compared with using chemicals, confirming the results of other research in the field. Quantum dots produced from tea leaves inhibit the growth of lung cancer cells.  They penetrated into the nanopores of the cancer cells and destroyed up to 80% of them.  This was a brand new finding, and came as a surprise to the team.

The research, published in “Applied Nano Materials”, is a collaborative venture between Swansea University experts and colleagues from two Indian universities.

Source: http://www.swansea.ac.uk/