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Nanofilter Cleans Water in Disaster Zones
Posted on: Wednesday, 13 August 2008, 18:00 CDT
By Luntz, Stephen
A nanomaterial coating on silica particles could offer the solution to one of the world's oldest and most destructive health challenges: how to remove bacteria and other pollutants from drinking water. In disasters like the Burmese cyclone, many of the deaths come from the destruction of water supplies. Flying in a few tonnes of food may keep thousands alive temporarily, but many times as much clean water is still usually inadequate.
However, Prof Peter Majewski of the University of South Australia's School of Advanced Manufacturing and Mechanical Engineering foresees a day when aid agencies could bring in coated sand and pour even the most polluted water through the equivalent of a coffee filter to obtain clean water. The nanomaterial on the surface of the silica would trap the cholera bacteria or Cryptosporidium parasites so reliably that the water could be drunk in safety.
Furthermore, Majewski believes that these nanofilters should be possible to produce at an affordable price. "We're using water, which is still not expensive, silica and a surfactant," he says. Majewski and his PhD students have experimented with quartz sand, priced at around $20 per tonne, for their silica and are also testing more upgraded silica from chemical industries.
Even the surfactant is not so expensive for use in the developing world, where 6000 people die each day due to a lack of clean drinking water. Furthermore, Majewski says it may be possible to reuse the filters after washing them in a slight acid. Alternatively, the pollutants and nanomaterials could be burnt off and the silica reused.
Majewski says it is not yet clear if the process is suitable for the vast purification plants of the developed world, but there are many other markets that may have potential. For example, the filtration system could prove suitable for removing bacteria from home swimming pools or to treat the waste from industrial plants such as pulp mills.
It even offers a way of desalinating seawater without electricity, although Majewski does not think this will be commercially viable on a large scale.
Source: Australasian Science
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Nano-foods
Nano-foods: something else to worry about
Reuters
Consumers already worried about genetically engineered or cloned food reaching their tables may soon find something else in their grocery carts to furrow their brows over - nano-foods.
Consumer advocates taking part in a food safety conference in Orlando, Fla., this week said foods produced by using nanotechnology are quietly coming onto the market, and they want U.S. authorities to force manufacturers to identify them.
Companies using nanotechnology say it can enhance the flavour or nutritional effectiveness of food.
U.S. health officials generally prefer not to place warning labels on products unless there are clear reasons for caution or concern. But consumer advocates say uncertainty over health consequences alone is sufficient cause to justify identifying nano-foods.
"Nanotechnology is the new genetic engineering ... and it's moving so fast," Jane Kolodinsky, a consumer economist at the University of Vermont, said at the conference.
New consumer products created through nanotechnology are coming on the market at the rate of three to four per week, according to an advocacy group, the Project on Emerging Nanotechnologies (PEN), based on an inventory it has drawn up of 609 known or claimed nano-products.
Nano-products in common use today include lightweight tennis rackets and bicycles, and sunscreens containing clear, nonwhite versions of zinc oxide and titanium dioxide.
thegazette.canwest.com
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Nanotechnology is revealing when it comes to fingerprints
(Nanowerk Spotlight) Archaeological evidence indicates that ancient Chinese and Babylonian civilizations already were using fingerprints to sign legal documents as early as 1000 BCE.
As early as 1880, Dr Henry Faulds, an English physician working in Tokyo, published a letter in the journal Nature suggesting the use of fingerprints for identification purposes. Today, fingerprints are still the primary method of identification of criminals although the techniques for fingerprint detection and enhancement have become hi-tech and involve nanotechnology applications. Some researchers even want to make it possible to use fingerprints to reveal drug and doping transgressions and to diagnose diseases (Nanotechnology fingerprint analysis could replace blood sample).
The most problematic of fingerprints are latent prints that are not readily visible and that require development by chemical and/or physical means. Usually, the choice of the technique for fingerprint development is dependent on the composition of latent fingerprints, on the type of substrate and on the ability of the technique to be applied in sequence in the context of the case.
A new review paper describes the current status of nanotechnology-based techniques such as application of metal-containing nanoparticles and nano-structured particles to fingermark detection. It concluds that nanotechnology is likely to play a major role in the future to deliver more selective and more sensitive ways to detect and enhance fingermarks.
"It is generally accepted that only a subset of all the latent fingermarks present on an exhibit are actually detected," Dr. Philip Maynard tells Nanowerk. "In other words, in routine casework, a non-negligible number of latent fingermarks probably remain undetected, and consequently cannot be exploited during the investigation. This explains why the demand for improved reagents for fingerprint development has continued in forensic science over the years."
Maynard, a lecturer at the University of Technology Sydney (UTS) and a forensic scientist with expertise in the areas of trace evidence and chemical/arson analysis, explains that the fingermark is a complex mixture of natural secretions of the body (mostly sweat from different types of glands) and contaminations from the environment.
"Secretions from three types of glands ? eccrine, apocrine, and sebaceous ? may be present in latent fingermarks. The constituents of the deposit are mostly water (99%) and minor amounts (up to 1%) of inorganic and organic compounds. Eccrine secretions are present to some degree in every latent fingermark but the composition varies in relation to age, sex, medical condition and diet along with environmental conditions post-deposition."
Another advantage of nanoparticles is the effect of certain quantum phenomena that become pronounced at a size scale below 100 nm (e.g. doping properties, interaction with light, electron transport properties) and which could allow the application of novel detection methods by forensic scientists.
The review focuses on metal particles in their elemental state (for example see: Nanotechnology reveals fingerprints), metal oxide particles, and metal sulfide particles and describes the current state-of-the-art research in each area although it cautions that some of these methods are not yet sufficiently mature for routine implementation in casework.
"Nanotechnology has proved to be a promising area of research for forensic fingerprint scientists and it is generally considered that nanotechnology may lead to the development of new materials and reagents with superior characteristics to conventional ones" says Maynard. "Nanotechnology provides new opportunities in surface-based science and because latent fingermark detection can be broadly seen as surface-based phenomena, it is obvious that nanotechnology is a prime candidate to allow completely different approaches to significantly improve detection sensitivity using chemical reagents.
By Michael Berger. Copyright 2008 Nanowerk LLC
Original font: www.nanowerk.com
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Crossing the blood-brain barrier with nanotechnology
(Nanowerk Spotlight) The challenge in treating most brain disorders is overcoming the difficulty of delivering therapeutic agents to specific regions of the brain by crossing the blood-brain barrier (BBB). This barrier ? a tight seal of endothelial cells that lines the blood vessels in the brain ? is a physiological checkpoint that selectively allows the entry of certain molecules from blood circulation into the brain.
The problem for scientists is that the BBB does not differentiate what it keeps out. BBB strictly limits transport into the brain through both physical (tight junctions) and metabolic (enzymes) barriers. With very few exceptions, only nonionic and low molecular weight molecules soluble in fat clear the BBB. For instance, alcohol, caffeine, nicotine and antidepressants meet these criteria. However, large molecules needed to deliver drugs do not. Thus, while the BBB naturally evolved in order to protect the brain from invasion of various circulating toxins and other harmful molecules, it also serves as a major impediment towards the brain-specific delivery of various diagnostic/therapeutic molecules needed for combating various neuronal disorders.
To date, delivery of therapeutic molecules into the brain often involves highly invasive techniques (like drilling a hole in the skull). The utter scarcity of techniques for brain-specific delivery of therapeutic molecules using non-invasive approaches has led researchers to increasingly explore the vast potential of nanotechnology toward the diagnosis and treatment of diseases/disorders incurable with present techniques.
Scientists have now reported a nanoparticle-based platform which 'tricks' the BBB into allowing the entry of the nanoparticle into the brain, using an approach that draws parallel to the 'trojan horse' concept. Certain proteins and peptides, such as the iron-transporting protein transferrin, are allowed free access across the intact BBB as they function as carriers of essential nutrients into the brain. By linking transferrin with rod-shaped semiconductor nanocrystals (quantum rods) ? an up and coming diagnostic agent which can also multitask as carriers of therapeutic molecules ? it was found that the transferrin helps the linked quantum rods to 'sneak' across the BBB into the brain.
This finding can have significant potential implications towards the development of brain-directed nanoparticle based diagnostic and therapeutic agents using minimally invasive procedures.
Confocal Microscopic image of blood brain barriers model treated with transferrin-conjugated quantum rods
Confocal Microscopic image of BBB model treated with transferrin-conjugated quantum rods (left) and unconjugated quantum rods (right). (Image: Dr. Prasad/University at Buffalo)
"Our work demonstrates a nanoparticle-based platform that will not only allow a direct visualization of the transmigration ability of various kinds of biomolecules across the BBB, but also facilitate the development of novel diagnostic and therapeutic nanoprobes for early diagnosis and therapy of various disorders of the brain, following systemic administration," Dr. Paras N. Prasad tells Nanowerk. "Quantum rods, owing to their high surface area, can be co-incorporated with other diagnostic and therapeutic molecules for targeted therapy of disorders of the central nervous system."
Prasad, Distinguished Professor of Chemistry, Samuel P. Capen Chair of Chemistry, and Director of the Institute for Lasers, Photonics, and Biophotonics (ILPB) at the University at Buffalo, together with a team of collaborators from ILPB, the Department of Medicine at Buffalo General Hospital, and the Institute of Optoelectronics at Shenzhen University in China, have published their findings in a paper in the May 13, 2008 online edition of Bioconjugate Chemistry ("Bioconjugated Quantum Rods as Targeted Probes for Efficient Transmigration Across an in Vitro Blood-Brain Barrier").
"We have also demonstrated that the successful BBB transport of quantum rods conjugated to more than one protein can be monitored simultaneously, by exploiting the fact that quantum rods emit in different colors upon a small change in their size" says Dr. Indrajit Roy, a Deputy Director of Biophotonics for the ILPB. "This type of 'multiplexed' imaging will potentially help in monitoring the efficiency of BBB transport of a number of biomolecules, which is expected to significantly expedite drug-discovery programs investigating various BBB transporter molecules."
"More importantly, we have discovered that the carefully functionalized quantum rods possess very low toxicity" says Dr. Ken-Tye Yong, Postdoctoral Research Associate in the ILPB. "This strongly suggests that quantum rods linked to drugs may be used as efficient therapy probes for treating brain diseases."
This new study is an extension of previous work by the group, where they have already shown that quantum rod/quantum dot bioconjugates can serve as targeted optical probes for two-photon fluorescence imaging of cancer cells ("Quantum Rod Bioconjugates as Targeted Probes for Confocal and Two-Photon Fluorescence Imaging of Cancer Cells").
The scientists explain that their research has implications in two directions: one towards the development of a nanoparticle-based 'theranostic' system for neuronal imaging which can also function as a delivery vehicle for therapeutic molecules; and the other towards the fabrication of a model system across which the BBB crossing efficiency of a number of potential BBB transporter molecules can be competitively evaluated.
Regarding the first case, while the active transport of liposomal and polymeric nanoparticulate formulations across the intact BBB has already been demonstrated by other research groups, Prasad points out that his team's findings unfold a new dimension in BBB transport using inorganic nanoparticles which are structurally robust and demonstrate the potential to transport multiple agents across the BBB. "These multiple agents can be selected so that they function in a synergistic way in the brain ? e.g. the efficiency of a therapeutic molecule can be monitored non-invasively in real-time using a co-incorporated diagnostic probe."
The second example is a first-time demonstration of its kind and is expected to significantly expedite drug-discovery programs investigating various BBB transporter molecules using a simple assay.
Potential applications of this work include:
# Co-delivery of diagnostic and therapeutic agents against brain-specific diseases/disorders/social concerns such as brain tumor, neuro-AIDS, obesity, drug addiction, etc.
# Enhanced understanding of the BBB, elucidation of mechanisms governing its structure, composition, and structural changes in response to various natural BBB transporters, undesirable toxins, infective viruses including HIV-1, and potential BBB disrupting molecules.
# Studying the efficiency and kinetics of BBB crossing of various BBB transporting molecules such as growth factors, insulin, transferrin, etc. Development of a test-kit that would competitively evaluate the efficiency of a number of such molecules in a multiplexed, ?high-throughput? manner.
"All these potential applications are also future directions for our work," says Prasad, but he cautions that particular challenges include development of a multimodal nanosystem carrying multiple diagnostic/therapeutic/targeting molecules, and the translation of this technique into clinical trials.
By Michael Berger. Copyright 2008 Nanowerk LLC
Original font: www.nanowerk.com
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