Filter"paper" made out of nitric oxide nanowires is effective at trapping germs and ruining them with light. This discovery via an EPFL lab could be put to use in personal protective equipment, as well as in ventilation and air conditioning systems.

Included in attempts to curtail the Covid-19 pandemic, newspaper masks are increasingly being made compulsory. These include the environmental impact of disposable masks made from layers of non-woven polypropylene plastic microfibres. Moreover, they just trap pathogens rather than destroying them. "But their use in the wider world - in which they're chucked into receptive waste bins as well as left on the street - can turn them into new sources of pollution ."

<span style="color: #ff6600;"><a style="color: #ff6600;" href="https://actu.epfl.ch/news/a-titanate-nanowire-mask-that-can-eliminate-pathog">Researchers at Forró's laboratory are working on a promising answer to this difficulty: a membrane made of titanium oxide nanowires, similar in appearance to filter paper however with antibacterial and antiviral properties.</a></span>

Their substance works by using the photocatalytic properties of titanium dioxide. When exposed to ultraviolet radiation, the fibers convert resident moisture into oxidizing agents such as hydrogen peroxide, which have the ability to destroy pathogens. "Since our filter is extremely good at absorbing moisture, it may trap droplets that carry viruses and bacteria," says Forró. "This creates a positive environment for the oxidation process, which is triggered by light."

<span style="color: #ff6600;"><a style="color: #ff6600;" href="https://actu.epfl.ch/news/a-titanate-nanowire-mask-that-can-eliminate-pathog">The researchers' work seems now in Advanced Functional Materials, also contains experiments which demonstrate that the membrane's ability to destroy E. coli, the reference bacterium in biomedical research, and DNA strands in a matter of seconds.</a></span> Based on these outcomes, the investigators assert - although this remains to be shown experimentally - that the process would be equally successful on a broad selection of viruses, including SARS-CoV-2.
Their article also states that fabricating such membranes could be achievable on a large scale: the lab's equipment alone is capable of producing around 200 m2 of filter paper each week, or sufficient for as many as 80,000 masks per month. In addition, the masks can be sterilized and consumed a thousand times. This would alleviate shortages and considerably lower the amount of waste created by disposable surgical masks. Finally, the manufacturing process, which involves calcining the titanite nanowires, makes them secure and prevents the probability of nanoparticles being inhaled by the user.

A start-up named Swoxid is already preparing to move the tech from the lab.

<em>The membranes could also be used in air treatment applications such as ventilation and air conditioning systems as well as in personal protective equipment."-</em>Endre Horváth, article's lead author and co-founder of Swoxid
<div class="content-src-label"><strong>Source:</strong></div>
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<span style="color: #ff6600;"><a style="color: #ff6600;" href="https://actu.epfl.ch/news/a-titanate-nanowire-mask-that-can-eliminate-pathog" target="_blank" rel="noopener noreferrer">Ecole Polytechnique Fédérale de Lausanne</a></span>

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<div class="content-src-label"><strong>Journal reference:</strong></div>
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Horváth, E., <em>et al.</em> (2020) Photocatalytic Nanowires‐Based Air Filter: Towards Reusable Protective Masks. <em>Advanced Functional Materials.</em> <span style="color: #ff6600;"><a style="color: #ff6600;" href="http://dx.doi.org/10.1002/adfm.202004615" target="_blank" rel="noopener noreferrer">doi.org/10.1002/adfm.202004615</a>.</span>

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