Researchers have described for the first time the diffusion of liquid water through nanochannels in molecular terms; nanochannels are extremely tiny channels with a diameter of 1-100 nanometers that scientists use to study the behavior of molecules. This study might have an important impact on water desalinization and filtration methods. The introduction of graphene membranes and carbon nanolayers will revolutionize water desalinization and filtration processes, as water diffuses rapidly through these materials when their pores are 1nm in diameter.
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Iran to Hold 4th Int’l Congress on Nanoscience, Nanotechnology
TEHRAN (FNA)- Nanoscience and Nanotechnology Research Center of Kashan University is slated to hold the Fourth International Congress on Nanoscience and Nanotechnology (ICNN2012) from September 8 to 10, 2012.
The organizers of the congress, which is due to be held in Kashan University, seek to create an opportunity for interaction between the Iranian researchers and their foreign colleagues.
Provision of an opportunity to introduce the latest progresses in the field of nanotechnology and strengthening cooperation between the Iranian and foreign researchers in this field are among the objectives of this congress.
The scopes of the congress are as follows:
– Nano-electronics and nanosensors
– Carbon nanomaterials such as fullerene, nanotubes, graphene.
Researchers are required to submit their articles to the secretariat of the congress before May 3, 2012.
Australians risking skin cancer to avoid nanoparticles
More than three in five Australians are concerned enough about the health implications of nanoparticles in sunscreens to want to know more about their impact. And while the initial scientific information released suggests little cause for alarm, it does justify the community’s confusion.
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That’s the message that emerges from a survey and three research papers on nanoparticles in sunscreens presented at the 2012 International Conference on Nanoscience and Nanotechnology (ICONN) in Perth this week.
Researchers reported that:
• some sunscreens that claim to be nano-free do in fact contain nanostructured material – highlighting the need for clear nano definitions;
• claims of the dangers of nano metal oxides in sunscreen might be overstated; and
• a very small amount of zinc from zinc oxide particles in sunscreens is absorbed through human skin
The Cancer Council of Australia reports that we have one of the highest rates of skin cancer in the world, with over 440,000 people receiving medical treatment for skin cancers each year, and over 1,700 people dying of all types of skin cancer annually.
The survey of public attitudes towards sunscreens with nanoparticles, commissioned by the Australian Department of Industry, Innovation, Science, Research and Tertiary Education and conducted last month, showed that about 17% of people in Australia were so worried about the issue, they would rather risk skin cancer by going without sunscreen than use a product containing nanoparticles.
Scientists from Australia’s National Measurement Institute and overseas collaborators reported on a technique using the scattering of synchrotron light to determine the sizes of particles in sunscreens. They found that some commercial sunscreens that claim to be ‘nano-free’ do in fact contain nanostructured material. The findings highlight the need for clear definitions when describing nanomaterials.
Researchers from RMIT and Nanosafe Australia reported on studies using human cells that show zinc oxide and titanium oxide particles used in sunscreens are as well-tolerated as zinc ions and conventional chemical sunscreens in human cell test systems.
A joint CSIRO and Macquarie University study found that a very small amount of zinc from zinc oxide particles in sunscreens is absorbed through human skin under normal conditions of sunscreen use but that it is a very small fraction of the levels of zinc normally found in blood. It is not known if the absorbed zinc is in the form of soluble zinc ions or zinc oxide particles.
When zinc oxide and titanium dioxide in sunscreens are reduced to the nanoscale they make the sunscreen transparent. The Australian Therapeutic Goods Administration has released a statement on safety of sunscreens containing nanoparticles that concluded: “… the current weight of evidence suggests that TiO2 (titanium dioxide) and ZnO (zinc oxide) nanoparticles do not reach viable skin cells, rather, they remain on the surface of the skin and in the outer layer of the skin…”
More information: More at http://www.tga.gov … s-060220.pdf
The full survey data is available at: http://www.innovat … ace-research
For more information on nanoparticles and sunscreens: http://cancer.org. … unscreen.htm
Artist’s conception of a nanopore drilled into a layer of graphene to speed up DNA sequencing.
One of the greatest promises of near-term nanotechnoloogy is cheaper DNA sequencing to speed the development of personalized medicine. There are not only genetic differences between different patients, but also genetic differences between, for example, different cancers of the same organ diagnosed in different patients, or even from different locations in the same patient, that can greatly affect the success of a therapy. Nanopore sensors are among the promising new third-generation DNA sequencing technologies being developed to make inexpensive whole genome sequencing a reality. A review of the potential of this emerging nanotechnology was published recently in Nature Nanotechnology [abstract]. The full text of the review “Nanopore sensors for nucleic acid analysis” has been made available by the authors for down-loading. Nanopores and other third generation sequencing technologies sequence single molecules of DNA in real time. Single molecules of DNA are pulled through a nanopore of some type and changes in the ionic current, dependent on whether an A, G, C, or T nucleotide is passing through the pore, are recorded. The review discusses the different types of nanopore that have been tried, both biological and solid-state, and the challenges encountered, such as reducing the speed at which the DNA molecule transits the nanopore, and improving sensitivity.
Research done by scientists at Harvard and MIT and published in Nature [abstract, free authors’ manuscript deposited in PubMedCentral] showed that a graphene sheet one or two atomic layers thick could form an electrode separating two liquid reservoirs so that current from ions passing through a nanopore in the graphene sheet could be measured, and the current blockade seen when DNA molecules passed through the pore indicated it should be possible to resolve individual nucleotides with an insulating membrane this thin. From a Harvard Gazette article by Michael Rutter “Graphene may help speed up DNA sequencing“:
… By drilling a tiny pore just a few nanometers in diameter, called a nanopore, in the graphene membrane, the researchers were able to measure exchange of ions through the pore and demonstrate that a long DNA molecule can be pulled through the graphene nanopore just as a thread is pulled through the eye of a needle.
“By measuring the flow of ions passing through a nanopore drilled in graphene we have demonstrated that the thickness of graphene immersed in liquid is less then 1 nm thick, or many times thinner than the very thin membrane which separates a single animal or human cell from its surrounding environment,” says lead author Slaven Garaj, a physics research associate at Harvard. “This makes graphene the thinnest membrane able to separate two liquid compartments from each other. The thickness of the membrane was determined by its interaction with water molecules and ions.” …
“Although the membrane prevents ions and water from flowing through it, the graphene membrane can attract different ions and other chemicals to its two atomically close surfaces. This affects graphene’s electrical conductivity and could be used for chemical sensing,” says co-author Jene Golovchenko, the Rumford Professor of Physics and Gordon McKay Professor of Applied Physics at Harvard, whose pioneering work started the field of artificial nanopores in solid-state membranes. “I believe the atomic thickness of the graphene makes it a novel electrical device that will offer new insights into the physics of surface processes and lead to a wide range of practical application, including chemical sensing and detection of single molecules.” …
When the researchers added long DNA chains in the liquid, they were electrically pulled one by one through the graphene nanopore. As the DNA molecule threaded the nanopore, it blocked the flow of ions, resulting in a characteristic electrical signal that reflects the size and conformation of the DNA molecule. …
As a DNA chain passes through the nanopore, the nucleobases, which are the letters of the genetic code, can be identified. But a nanopore in graphene is the first nanopore short enough to distinguish between two closely neighboring nucleobases.…
More recently another group at Harvard has integrated nanowire field-effect transistors with a solid-state nanopore to achieve rapid, sensitive detection of the very small currents created as DNA molecules zip through the nanopore. From a Harvard Gazette story by Peter Reuell “Reading life’s building blocks“:
Scientists are one step closer to a revolution in DNA sequencing, following the development in a Harvard lab of a tiny device designed to read the minute electrical changes produced when DNA strands are passed through tiny holes — called nanopores — in an electrically charged membrane.
As described in Nature Nanotechnology [abstract, free full text provided by authors] on Dec. 11, a research team led by Charles Lieber, the Mark Hyman Jr. Professor of Chemistry [and also winner of the 2001 Feynman Prize in Nanotechnology-Experimental], have succeeded for the first time in creating an integrated nanopore detector, a development that opens the door to the creation of devices that could use arrays of millions of the microscopic holes to sequence DNA quickly and cheaply.
First described more than 15 years ago, nanopore sequencing measures subtle electrical current changes produced as the four base molecules that make up DNA pass through the pore. By reading those changes, researchers can effectively sequence DNA.
But reading those subtle changes in current is far from easy. A series of challenges — from how to record the tiny changes in current to how to scale up the sequencing process — meant the process has never been possible on a large scale. Lieber and his team, however, believe they have found a unified solution to most of those problems.
“Until we developed our detector, there was no way to locally measure the changes in current,” Lieber said. “Our method is ideal because it is extremely localized. We can use all the existing work that has been done on nanopores, but with a local detector we’re one step closer to completely revolutionizing sequencing.”
The detector developed by Lieber and his team grew out of earlier work on nanowires. Using the ultra-thin wires as a nanoscale transistor, they are able to measure the changes in current more locally and accurately than ever before.
“The nanowire transistor measures the electrical potential change at the pore and effectively amplifies the signal,” Lieber said. “In addition to a larger signal, that allows us to read things much more quickly. That’s important because DNA is so large [that] the throughput for any sequencing method needs to be high. In principle, this detector can work at gigahertz frequencies.”
The highly localized measurement also opens the door to parallel sequencing, which uses arrays of millions of pores to speed the sequencing process dramatically.
In addition to the potential for greatly improving the speed of sequencing, the new detector holds the promise of dramatically reducing the cost of DNA sequencing, said Ping Xie, an associate of the Department of Chemistry and Chemical Biology and co-author of the paper describing the research. …
“Right now, we are limited in our ability to perform DNA sequencing,” Xie said. “Current sequencing technology is where computers were in the ’50s and ’60s. It requires a lot of equipment and is very expensive. But just 50 years later, computers are everywhere, even in greeting cards. Our detector opens the door to doing a blood draw and immediately knowing what a patient is infected with, and very quickly making treatment decisions.”
Rapid, inexpensive DNA sequencing and other nanotechnology-based innovations in drug-delivery and tissue regeneration may transform health care in the coming decade.
Carbon nanotubes and graphene consist of just a couple of layers of carbon atoms, but they are lighter than aluminium, stronger than steel and can bend like spring-coils. Physicist Niklas Lindahl at the University of Gothenburg, Sweden, has been studying the unique properties of the materials, which in future may result in improved electronics and light, strong material.