Cleaning Air with Poetry: Surprising Uses of a Titanium Dioxide Catalyst

The 21st Century has brought with it a growing acceptance of the severity of climate change, with Forecasts of the Intergovernmental Panel for Climate Change (IPCC) projecting a 2°C rise in global temperature by 2050 based on current levels of greenhouse gas emissions. The recent Paris Agreement of the 2015 United Nations Climate Change Conference brought a global consensus to make efforts to limit the global temperature rise to 1.5°C by 2050. However, despite such promising commitments, the majority of measures to combat global warming and anthropogenic pollution have so far been directed only towards the prevention of further damage being done. It is likely that more innovative methods may be required to help reverse the accumulation of greenhouse gases and to improve the air quality of urban environments, where smog is having a severe effect on public health.

One such innovation with green potential involves a clever application of catalytic nanoparticles. Refreshingly, this innovation originated from collaboration between the arts and science, and is invigorating in its use of the natural curiosity and creativity of humanity to address man-made issues. Through this article, I aim to describe to you how you yourself can assist in removing harmful pollutants from the air simply by walking along a street, or even just by reading a poem.

Pollutive gases can be broadly divided into two groups: The greenhouse gases (such as methane, carbon dioxide, and nitrous oxide), which absorb radiation in the upper atmosphere, and toxic surface-level pollutants (such as carbon monoxide, volatile organic compounds, and nitrogen oxides (NOx)). Surface-level pollutants are predominantly derived from industrial or transport emissions, and in London alone are believed to be responsible for thousands of premature deaths every year.

Actively reducing levels of air pollutants is likely to require some form of catalytic process (put in mind the catalytic conversion of carbon dioxide to oxygen performed by plants), and so efforts have recently been made to neutralise toxic surface-level pollutants through use of synthetic catalysts in urban environments (where both the concentration of pollution, and people, is at its greatest). These catalysts hold significant promise for the future, and it was through the work of Prof. Tony Ryan that I was first introduced to the potential of one such catalyst, the titanium dioxide (TiO2) nanoparticle.

CatClo-treated jeans displayed in Sheffield’s Winter Garden. Photograph courtesy of Helen Storey Foundation.
CatClo-treated jeans displayed in Sheffield’s Winter Garden. Photograph courtesy of Helen Storey Foundation.

Nanoparticles are materials on the scale of a millionth of a millimetre. With such miniaturisation comes a substantial increase in available surface area on which reactions can take place, and often a change in chemical properties. When exposed to sunlight, TiO2 nanoparticles provide a catalytic surface for the production of peroxides, which can then react with nitric oxide to produce nitric acid and nitrates, effectively removing the toxic nitric oxide from the breathable atmosphere (1,2).

The current applications of TiO2 nanoparticles include the coating of walls and windows of buildings, and surfaces of pavements and roads (3,5), although the true motive behind this use is not to reduce pollution. TiO2 nanoparticles also confer a self-cleaning property as the lipophilic TiO2 attracts a layer of water between a surface and dirt particles, allowing dirt to simply wash away with rainfall. By such applications alone, concentrations of nitric oxide have been shown to fall by 20-60% (6,7).

A particularly inspirational use of TiO2 nanoparticles arose from the collaboration between Prof. Ryan and the fashion designer, Prof. Helen Storey. This meeting of arts and science led to the development of CatClo, a laundry additive of TiO2 nanoparticles which, when washed into clothing, imbues them with the nanoparticles’ photocatalytic quality. It is predicted that CatClo-treated clothing would remove roughly 5 grams of nitric oxide per day when worn in an urban environment, equivalent to the daily nitric oxide emissions of the average car (8). Although the CatClo additive is eventually removed by subsequent repeated washes, the additional antibacterial effect conferred by the nanoparticles may extend wearable time between washes.

Prof. Ryan has further demonstrated the versatility of TiO2 nanoparticles through an art installation involving prestigious poet, Simon Armitage. Penned by Armitage, a poem entitled ‘In Praise of Air’ was displayed in the centre of Sheffield, printed on 10 m x 20 m material ingrained with TiO2 nanoparticles. This installation was estimated capable of removing the nitric oxide emissions of as many as 20 cars daily.

Installation of the “photocatalytic poem”, In Praise of Air, in Sheffield. Present are Simon Armitage (right), and Prof. Tony Ryan (left). Photo from
Installation of the “photocatalytic poem”, In Praise of Air, in Sheffield. Present are Simon Armitage (right), and Prof. Tony Ryan (left). Photo from

Just such a merging of arts and science is what separates the projects of Prof. Ryan from other scientific endeavours combating climate change, and it stands as a striking example of how the applications of an invention can be brought to a wider audience by simple, yet creative, means.

More information can be found regarding CatClo at

Post by: David Young


1.    Ohko, Y., Nakamura, Y., Fukuda, A., Matsuzawa, S. & Takeuchi, K. Photocatalytic Oxidation of Nitrogen Dioxide with TiO2 Thin Films under Continuous UV-Light Illumination. J. Phys. Chem. C 112, 10502–10508 (2008).

2.    Toma, F. L., Bertrand, G., Klein, D. & Coddet, C. Photocatalytic removal of nitrogen oxides via titanium dioxide. Environ. Chem. Lett. 2, 117–121 (2004).

3.    Shen, S., Burton, M., Jobson, B. & Haselbach, L. Pervious concrete with titanium dioxide as a photocatalyst compound for a greener urban road environment. Constr. Build. Mater. 35, 874–883 (2012).

4.    Chen, J. & Poon, C. Photocatalytic construction and building materials: From fundamentals to applications. Build. Environ. 44, 1899–1906 (2009).

5.    Hüsken, G., Hunger, M. & Brouwers, H. J. H. Experimental study of photocatalytic concrete products for air purification. Build. Environ. 44, 2463–2474 (2009).

6.    TX Active® The Photocatalytic Active Principle. (2009).

7.    Tx Active®. (2006).

8.    Pollution-busting laundry additive gets set to clean. (2012).

This Christmas remember: Wash your hands not your turkey!

2169185215_c80cc1d607_zWith Christmas fast approaching, many of us will be stocking up ready for a festive feast – the centrepiece of which is usually a nice plump goose or turkey. But this year, alongside preparations to ensure your bird is moist and mouthwatering, it’s important to also keep in mind the dangers associated with putting your turkey under the tap!

Raw poultry provides a home for Campylobacter and Salmonella – the most common causes of food poisoning in the UK. In fact, in 2014 it was found that approximately 7 in 10 chickens sold in British supermarkets were contaminated by Campylobacter. But don’t fret, as a rule, good kitchen hygiene and thorough cooking are usually enough to avoid infection.

However, there is one important aspect of kitchen hygiene which seems to be regularly overlooked, this being the importance of not washing your bird before cooking. Placing a turkey under the tap causes an invisible storm of bacteria to spray from your meat, settling on anything within range (from clean utensils to previously sterile working surfaces). This cross contamination significantly increases the risk of infection to yourself and your family.

2187298129_ea44b55d86_zLast year almost 900 people took part in a national survey carried out by researchers at the Universities of Manchester and Liverpool which found that around 50% of participants always or usually washed their turkeys under the tap before cooking. This means that, despite warnings from the food standards agency, the message is still not getting across.

This year the Brain Bank wants to add our voice to this campaign and keep our readers healthy over the festive period. So, this Christmas make sure to treat your favorite bird correctly and remember – Wash your hands not your turkey!

Wishing wish you all a happy and healthy holiday!

Post by: Sarah Fox

Your brain on bugs: How the bugs in your gut may influence your mental well-being.

Cuddly microbes: Note - significantly cuddlier than those found in your gut!
Cuddly microbes: Note – significantly cuddlier than those found in your gut!

Did you know that you’re never alone? In fact your body provides housing for a dizzying array of microorganisms. These tiny tag-alongs colonise a number of different ecosystems within the human body, including a whole host which make their home in our digestive system. It is estimated that there are around 1014 microorganism living in the gut, meaning that our guts actually contain around 10-times more microbes than human cells! It is therefore not surprising that scientists are starting to uncover a wide range of effects these internal residents have on our development and overall health.

Historically, neuroscientists have remained skeptical regarding the effects of gut microbes on our mental well-being. However, recent clinical observations and animal studies suggest that microbes in the gut can influence behaviour through alterations in brain physiology and neurochemistry – and now the neuroscience community is starting to take notice.

13924249304_5ba9f7f228_zThe most compelling evidence so far of a brain-gut link comes from mice raised in sterile germ-free conditions – these mice are born by cesarean (to prevent them from picking up microbes that reside in their mothers’ birth canals) and raised in a strictly sterile environment, meaning they don’t come into contact with microbes present in the normal mouse digestive track. Studies in these animals show that germ-free mice have an altered response to stress compared to mice harbouring a normal compliment of microbes. Interestingly, when germ-free mice are moved away from their sterile homes and back into normal cages (where they will be exposed to many microbes), their behaviour does not revert back to that of normal mice, however the behaviour of their offspring does. This suggests that there may be a critical time window, early in development, where microbes have the greatest effect on brain chemistry. This may prove to be an important consideration for anyone having a cesarean birth. Indeed, a small number of hospitals will rub the mouth and skin of babes born through cesarean section with a piece of gauze from the mother’s vagina, to ensure the baby inherits the same vaginal microbes it would have gained through a natural birth.

In addition to this, in 2011, a team of scientists from McMaster University in Hamilton, Canada, found that they could transfer behavioural characteristics between different mouse strains by simply transplanting gut microbes from one animal to another. For example, it was possible to make shy mice more outgoing by transplanting them with gut microbes from their more outgoing counterparts. Also, some research suggests that transplanting faecal bacteria from humans with IBS and anxiety into mice can cause these mice to become more anxious – a finding which is simultaneously gross and amazing.

It has long been recognised that the brain and gut are connected – indeed, anyone suffering from anxiety is likely to have numerous tales of the negative impact this has on their digestive system. But, how does the gut communicate with the brain? Well, researchers are now starting to find answers to this question.

14599057004_9dc53af6f9_zFirstly, microbes in the gut break down complex carbohydrates into short-chain fatty acids, many of which influence the structure of the blood-brain barrier (a semi-permiable barrier controlling the passage of cells, particles and large molecules into the brain). This means that gut microbes may be able to control what passes into the brain. It has also been found that gut microbes can directly alter neurotransmitter levels – perhaps providing a conduit by which they can communicate with neurones. Specifically, certain metabolites from gut microbes cause cells lining the colon to produce Seratonin (a neurotransmitter often targeted by antidepressant ‘SSRI-type’ drugs). These finding may point towards new and promising research areas in the fight again mental illness.

However, we must be aware that scientists still don’t know how well this research will actually translate into humans. In fact, as we might expect, preliminary research into the brain-gut connection in humans suggests significant complexity and a need for further research. Neuroscientist Rebecca Knickmeyer who is currently working in this field says “There’s probably more speculation than hard data now. So there’s a lot of open questions about the gold standard for methods you should be applying. It’s very exploratory”. So, there may still be a long way to go before we fully understand how your internal ecosystem affects your mental well-being. But, perhaps in the future we may see probiotics prescribed alongside more traditional treatments for mental health problems.

Post by: Sarah Fox