Blog @ NanoVic - Nanotechnology Blog

The recent reports of the potential medical risks associated with carbon nanotubes, with a study in Nature showing asbestos-like responses in mice, has highlighted the urgent need for toxicity studies with nanomaterials.

But with so many new materials being created, and a huge variety of ways which toxicity can be measured, what is the best way for this field to go forward? The gold standard for examining toxicity of any material is animal testing, which is a laborious and costly process. Animal testing also tends to focus testing few types of material at a time, when there are many factors which may contribute towards nanomaterial toxicity including particle shape, size, composition and surface.

So why not go the way that drug discovery has gone in the last couple of decades, and get robots to do the work for you? Exactly this has been done by a group of researchers headed by Stanley Shaw at the Massachusetts General Hospital in Boston. Their approach, reported in the latest issue of PNAS, uses a cell-based assay. Human and mouse cells from different tissues including liver and blood were placed into small wells. A robot was then used to dispense the different nanoparticles into each well. In this initial study they have tested 50 different types of nanoparticles at a time, testing each nanoparticle at different concentrations. Various cellular markers of viability and metabolic activity were then measured in response to the addition of the nanoparticles, to create a profile for each material tested. This makes this study one of the largest of it’s kind so far, analysing about 24,000 different wells for nanotoxicity!

Nanoparticles that clustered together showing similar profiles in the cell assay were then tested by injection into mice, and showed that they also behaved similarly in vivo.

Whilst tests like this will never replace animal toxicity studies, it provides a much better starting point, allowing researchers to identify new particles whose effects on cells are similar to those of particles that are known to be safe. This makes it easier to pick which ones to test in animals.

This pilot study holds promise for allowing researchers to rapidly evaluate the ever increasing number of nanomaterials produced, something that consumers are demanding of these new products.

Following on from Lisa’s last post, Japanese scientists have discovered that carbon nanotubes could also help to speed up the recovery of broken bones.

Carbon nanotubes placed in contact with damaged bones were found to not only help to regenerate bone tissue, but to also reduce inflammation during healing. Measurements taken as the new bone was forming revealed that the carbon nanotubes become integrated into the bone matrix and appear to act as a starting point for new bone tissue to begin to grow. When the nanotubes were used in conjunction with a bone morphogenetic protein (BMP), commonly used to facilitate bone regrowth, the production of new bone material was also accelerated even further.

Conventional methods for treating broken bones is a lengthy process, that involves weeks of cast or splint wearing for the patient. The new technology could lead to much faster healing processes for those who experience broken bones.

The recent publication of a research paper describing asbestosis-like pathological changes in mice exposed to carbon nanotubes has captured world attention. Nothing like a bit of bad news to get everyone focussed on nanotechnology, huh?!

The new study was performed by an alliance of researchers from the USA and the UK, and involved injecting multi-walled carbon nanotubes (MWNTs) into the abdominal cavities of mice. In this animal model, long, rigid MWNTs were found to trigger chronic inflammatory changes in abdominal mesothelial cells, a response comparable to that seen in control mice injected with asbestos fibres. A similar inflammatory response is thought to lead to fatal mesothelioma in some humans exposed to asbestos. Taken in a very broad sense, the findings suggests that human exposure to long, rigid MWNTs could have consequences that we do not yet fully understand. Clearly further studies do need to be conducted in this area. Interestingly, short MWNTs and single-walled carbon nanotubes had no apparent deleterious effects under the same study conditions. So let’s not shut the door on carbon nanotubes just yet…..

……..but now that everyone is watching, what’s going to happen next? Well for a start nanotechnology researchers and industries relying on the future of nanotechnology do need to take studies such as this into account. Social and environmental groups such as Friends of the Earth have a strong and informed involvement in the nanotechnology debate; they are already calling for greater public involvement in nanotechnology research and believe that the health implications of exposure to nano-sized materials need to be better characterised. Public forums like that recently conducted by the Australian Office of Nanotechnology may assist in this regard. I am interested as to whether any general news agencies picked up this story: use the comments option on this blog to let me know if you heard or saw wind of this research on your local radio or news stations. Let’s get a discussion going!

The use of nanotechnology in wound healing has been reported before, with the anti-microbial properties of nanoparticles (see here for a big selection of the literature) of silver being incorporated into band-aids by companies such as Nucryst. Another spin-out company Arch therapeutics has just started up coming out of research performed in the US, where researchers have found remarkable properties of a liquid they’ve dubbed ‘Nanohemostat’, that when applied to wounds stops bleeding almost instantly.

The study, reported in Nanomedicine, showed that the Nanohemostat solution stops blood flow in less than 10 seconds at surgical cut sites in the brain, spinal cord, femoral artery, and liver. The solution contains a mixture of small protein fragments, or peptides, which when applied form a nanoscale fibrous scaffold, producing a gel like seal on wounds, instantly stopping bleeding. Exactly how or why this scaffold is formed and why it is so effective is yet to be determined.

The people of South Australia, faced with living in the driest state on the driest continent on earth, know the value of clean fresh water. Researchers at the Ian Wark Research Institute at the University of South Australia have used a nano approach to produce clean, safe drinking water. Billions of people around the world do not have access to safe drinking water, and the result is that a child dies every 15 seconds due to water-bourne disease. Methods for purifying water often require complex and expensive equipment that is difficult to maintain in areas around the world which need this technology the most.

In this study, reported in the International Journal of Nanotechnology, silica beads were coated with an active material based on a hydrocarbon with a silicon-containing anchor. This formed a nano-layer around each bead, so called Surface enegineered silica (SES). The process works by simply mixing Surface engineered silica beads with contaminated water. After stirring for an hour and filtering out the beads the water was tested. Biological molecules, pathogens such as viruses like the Polio virus, bacteria like Escherichia coli, and Cryptosporidium parvum, which is a waterborne parasite were all removed. This process was effective across the normal pH ranges of drinking water, and the researchers attribute the removal of organic material by electrostatic attraction and immobilisation on the surface of the particles.

This is a great example of how nanotechnology is not just a ‘gimmick science’ aiming to produce endless gadgets for us, but how it is a science that can genuinely have an impact on improving the lives of many people. And also a great example of Australian nanotechnology at work!

I’m sure most of you have had the rather nasty experience of food poisoning. For me, all it takes is catching a glimpse of one of my Aunt Judy’s chicken sandwiches to trigger my gag reflex. Ooohhh, the family Easter picnic 2005 will live with me forever.  Personal anecdotes aside, food-borne pathogens are an issue not only because they cause debilitating illness and death, but also because they are relatively slow to diagnose.  This is probably not so critical for the family picnic, but can save lives in the case of restaurants and establishments such as elderly residential facilities.  Current tests to detect Salmonella for example, can take up to 5 days to obtain a result and are relatively insensitive if only a low level of bacteria is present. A new nanotechnology-based biosensor has been developed to address this issue. As reported by Nanowerk, the American and Korean research team  fabricated a hetero-structured silicon/gold nanorod array by the glancing angle deposition (GLAD) thin film method and functionalized it with anti-Salmonella antibodies and organic dye molecules. The test works by amplification of the dye’s fluorescent signal when Salmonella is present.  Specifically, binding of Salmonella bacteria to gold nano-rod coupled antibodies enhances the fluorescence of the dye molecules which are immobilised on silicon.  The test is specific, sensitive and rapid, and can probably be adapted to suit detection of other food-borne pathogens as well.  Sounds good to me, Auntie Judy.

Nanotechnology: The Power of Small, the first major television series to look at the implications of advances in nanotechnology, will begin airing on local US public broadcasting stations in April.

The series’ three programs explore critical questions about nanotechnology’s potential impact on privacy, the environment and human health: Will nanotechnology make you safer, or will it be used to track your every move? Will nanotechnology keep you young, and what happens if you live to be 150? Will nanotechnology help clean up the earth, or will it be the next asbestos?

The programme is funded by the National Science Foundation (NSF) and involves the host asking policymakers, scientists, journalists and community leaders to wrestle with difficult but essential issues about nanotechnology’s potential to impact people’s privacy and security, health and environment. Featured experts include Harvard University researcher George M. Whitesides, PEN chief scientist Andrew Maynard, and author Joel Garreau, among others.

To view the series click here

As readers of the Nanovic website, you may be aware of our role in developing nanotechnology-enabled transdermal patches for vaccination.  But have you ever wondered about what sort of research and development needs to go into developing a new vaccine? Of course the material to be injected should undergo rigorous testing from a health and safety point of view. But what about the actual mechanism - how do we know that the stuff being injected actually (1) gets to where we want it to go (i.e. is delivered through and released into the skin), (2) reaches the appropriate cellular components of our immune system, and (3) results in the kind of immune response that we want (i.e. leads to protective immunity).  Several presentations at ICONN2008 by researchers from the Australian Institute for Bioengineering and Nanotechnology (AIBN), University of Queensland focussed on these exact issues with respect to nanopatches. Nanopatches developed by the AIBN have a micro-nanoprojection array structure which can be successfully coated with biomolecules such as DNA and proteins. When applied to the skin, the patch design results in accurate, efficient and safe delivery of biomolecules to skin Langerhans cells (immune activating cells).  Associated immunological analysis shows that while the patches don’t create an overt and uncomfortable inflammatory reaction in the user, at the microscopic level immune changes are occurring. Sounds like highly promising vaccine technology to me. The AIBN research group is led by Professor Mark Kendall. 

A gecko-inspired medical adhesive may have potential applications for sealing wounds and for replacement or augmentation of sutures or staples. 

US researchers have used a polymer poly(glycerol-co-sebacate acrylate) and modified the surface to mimic the nanotopography of gecko feet, which allows attachment to vertical surfaces.  Ideally these adhesives would also have the ability to deliver drugs or growth factors to promote healing.  The findings have been published in Proceedings of the National Academy of Sciences.

As a first demonstration, a gecko-inspired tissue adhesive from a biocompatible and biodegradable elastomer combined with a thin tissue-reactive biocompatible surface coating was been created. Tissue adhesion was optimized by varying dimensions of the nanoscale pillars, including the ratio of tip diameter to pitch and the ratio of tip diameter to base diameter. Coating these nanomolded pillars of biodegradable elastomers with a thin layer of oxidized dextran significantly increased the interfacial adhesion strength on porcine intestine tissue in vitro and in the rat abdominal subfascial in vivo environment.

Perhaps this might also lead to taking the ‘ouch’ out of removing bandaids from the skin!

Turmeric has been used as a spice and colouring agent in Indian food for centuries, but with the help of nanotechnology, could it also be an effective cure for cancer?

While its therapeutic benefits have also long been realised in India, it was not until recent years that it was found that a compound in tumeric, called curcumin, which gives the spice its bright yellow colour, also possesses anti inflammatory and cancer protecting properties, having the ability to induce death in human cancer cells, while being non-toxic to normal cells.

So why then hasn’t curcumin become mainstream in cancer treatment? Well, the therapeutic effects of orally administered curcumin are limited to the lower intestinal tract, and large doses are needed before the drug can be absorbed in sufficient quantities to reach other parts of the body. This is mainly due to the poor solubility and resultant poor absorption of curcumin – but this is where nanotechnology may be able to help.

Researchers at the Johns Hopkins University are investigating the potential of creating nano-sized particles loaded with curcumin, which they are calling nanocurcumin. Unlike normal curcumin that does not dissolve in water and forms visible flakes impossible to administer via injection, nanocurcumin is small enough to be administered intravenously, avoiding the digestive system and overcoming the problem of absorption.

They have also shown that nanocurcumin is just as effective as normal curcumin against human cancer cells, and hope future studies to explore the use of nanocurcumin in clinical trials will enable them to further establish the potentials of this ancient medicine, which they hope could one day become commonplace in cancer treatment.