Blog @ NanoVic - Nanotechnology Blog

Dye-sensitized solar cells are a type of solar cell which uses an organic dye to to absorb incoming photons and produce excited electrons. Have a look here for a nice diagram of one. Typically, these sorts of cells contain a transparent, conductive coating (typically an oxide such as titanium dioxide, on glass), acting as the anode. A separate coating, on the other plate, consists of platinum and acts as a catalytic conductor.

These types of coatings have their drawbacks though. The oxide films work best when they are spread on rigid, stable structures such as glass, limiting the types of structures that can be made. Platinum films are effective, but expensive to produce.

In order to tackle these problems researchers tried to replace both of the films with nanotubes. This meant finding a way to achieve the optimal parameters for transparency, conductivity and catalytic function. Ordinarily, carbon nanotubes are mid-range for these three properties. Researchers found that introducing defects into the tubes, by exposing them to ozone which adds extra chemical groups into the tube, they actually found a big increase in the catalytic function. A great example of how changes in the structures of nanomaterials can have such huge effects on their properties. The link to the research article can be found here.

The researchers are currently applying to patent this technology, which will hopefully mean cheaper, more flexible solar cells on their way to meet the demands of the ever increasing renewable energy market.

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.

Kristin and I (both from Bridge8) attended the Australian Office of Nanotechnology (AON) public forum in Adelaide on the 8th of May. Host Belinda Barr (representing Primary Industries and Resources, SA and Australian Science Communicators) was not only scientifically literate, but a barrel of laughs to boot. She unashamedly illustrated the itty-bitty scale of what we were talking about by describing the size descrepancy between the tips (blond, diameter = 15-50,000 nanometres) and the roots of her hair (dark, diameter = 50-180,000 nanometres).  Belinda also introduced us to the interactive voting gadgets provided by the AON to gauge audience responses to nanotechnology issues throughout the evening. We managed to ascertain that 80% of attendees thought that the benefits of nanotechnology outweighed the risks, and that 95% of us believed it was worth spending more money on nanotechnology research. 81% of respondants would buy a product that they knew had nanotechnology in it.  Unfortunately, the technology then failed us and we had to resort to good old-fashioned hand raising to answer questions. This raised an interesting point in itself, which was that as soon as the anonymity was removed, most respondants were too shy to publically admit their opinions on issues around nanotechnology. Surely this is a problem! Not just with nanotechnology, but with science on the whole - members of the public don’t feel informed and confident enough to discuss new and emerging technologies. This issue later emerged as a uniting theme across all 3 speakers at the forum.

Joe Shapter (School of Chemistry, Physics and Earth Sciences, Flinders University)
- “Science drives change! The public as a whole needs to be informed and involved in science”.

Georgia Miller (Friends of the Earth, Australia)
- “There is almost no recognition that the public has the right to be involved in decision-making” with respect to nanotechnology and other new technologies.
- “We are here today because we don’t want nanotechnology to repeat the mistakes associated with past technologies”.

Once Asa Janting (National Measurement Institute) reassured us that “Yes, we can measure things we can’t see!”, the evening progressed, and some interesting discussions occurred between the audience and panel members. Topics covered included:
- what is nanotechnology?;
- what can nanotechnology offer us now and in the future?;
- the public should be actively involved in the development and use of nanotechnology.

We look forward to more AON events bringing nanotechnology to the public. Next time, I would be very interested to see a breakdown of the types of people attracted to attend - were they students, scientists, university graduates, teachers? This at least would give us an idea of what societal groups are already aware that nanotechnology exists, and who we need to target to improve public access into the future.

Researchers at Swansea University are developing a new, eco-friendly nanomaterial that they claim could generate as much electricity as 50 wind farms.

They are investigating ways of painting solar cells, which efficient at capturing low light radiation, onto the flexible steel surfaces commonly used for cladding buildings. This could then create buildings that could power themselves!!

Researchers are working closely with a company that produces around 100 million square meters of steel building cladding a year. If all this cladding was treated with the new solar cell material, it could be generating 4,500 gigawatts of electricity a year, the equivalent of 50 wind farms!

My daughter Clem and I spent some time recently playing with “magic sand”: super-hydrophobic powder from Educational Innovations.  It is a compelling demonstration, but we hadn’t many good ideas about applications.  Just today, though, I saw that Oak Ridge National laboratory in the US have developed a new super-hydrophobic coating, which can be made cheaply (from powdered glass) and applied over large surfaces.

The thing that attracted me was the description of how the nano-structured material “maintains a microscopic layer of air on surfaces even when submerged in water, resulting in a profound change in the basic water-solid interface”. The inventor, John Simpson likes to refer to this as the “Moses effect” – and I love the name!  He also speculates about how such a layer could significantly reduce the drag experienced by a ship moving through water, potentially saving a lot of energy.

There’s more…  Another feature of this powder is its thermal insulation. Water does not enter the grain pores because the powder grains are superhydrophobic. This results in a dry breathable coating with trapped insulating air throughout. And, because the powder consists almost entirely of porous amorphous silica, it also makes a very good electrical insulator. In addition, since the powder creates a layer of air between the coated substrate and any water on the surface, water-based corrosion of the substrate is greatly reduced or entirely eliminated. 

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!

Researchers at Cornell University, New York have come up with a new use for carbon nano-structured buckyballs. The novel idea relies on the capacity of buckyballs to enhance electronic resonances at low voltage during memory creation in flash software (which most of you have in your mobile phones and digital cameras). As reported by naturenews, this is an exciting development since “the major bottleneck of the current flash memories is the voltage” (Tuo-Hung Hu, Cornell University). Put simply, buckyball-enhanced resonance means less voltage is required to create or alter memory. In terms of your hardware, this translates into [1] reduced need for peripheral circuitry (i.e. smaller devices) and [2] longer battery life spans. Sweet.

And for those of you who are too young (or old) to understand the inspiration behind this blog title, here’s a reminder from 1982. FYI, a ‘dutchie’ is a Jamaican cooking pot.