Most viruses spread either through drops of liquid or direct contact. Pathogens can remain infectious for a long time, especially in contaminated water. So far, removing them from water has only been possible with the use of complex and environmentally harmful techniques. Researchers have now developed a virus filter that is not only effective, but also easy to manufacture.
Combination filter cleans water
The removal of dangerous viruses such as the coronavirus SARS-CoV-2, Ifnfluenza or rotaviruses from water is often only possible with processes such as reverse osmosis or with filters containing nanosilver. A team led by Archana Palika from the Swiss Federal Institute of Technology in Zurich (ETH) have now developed a new type of filter based on a network of whey proteins and iron nanoparticles. These are biocompatible materials.
The filter consists of denatured whey proteins which, under the influence of acid and when heated to around 90 degrees, combine to form fine amyloid fibrils. Then hydrated ferric chloride is added. In addition, the pH value of the solution is increased again by means of sodium hydroxide solution. The ferric chloride is transformed into iron hydroxide nanoparticles, which attach to the amyloid fibers created from the whey proteins. These nanoparticles are positively charged and can attract viruses, which are usually negatively charged. This works both with enveloped viruses such as influenza viruses or SARS-CoV-2, but also with non-enveloped pathogens such as rota or enteroviruses.
With whey proteins against viruses
In tests with various viruses – both with and without a shell – the researchers were able to show how well their filter works. They contaminated water with the coronavirus SARS-CoV-2, the influenza virus H1N1 and several bacteriophages, among others. The exposure was around one million infectious units per milliliter. In the tests, the virus concentration in all samples fell below the detection limit after passage through the filter membrane. “The membrane thus reduced the infectious potential by more than six orders of magnitude“Explain the researchers. In further tests, they found that the viruses were not only filtered, but also inactivated by the iron nanoparticles.
The combination of Esen hydroxide nanoparticles with the whey proteins makes the filter membrane particularly effective. The membrane was primarily designed by the scientists as a filter for sewage treatment plants and in drinking water treatment, but it could also be used in air filter units or even masks. “We are aware that the new coronavirus is mainly transmitted via droplets and aerosols. But even then, it must always be surrounded by water. The fact that we can also remove it from the water very efficiently underscores the wide range of applications of our membrane“, Says senior author Raffaele Mezzenga from ETH Zurich.
Inexpensive to manufacture
The membrane is also simple and inexpensive to manufacture. Thanks to the use of biocompatible materials, it has an excellent environmental balance. It can also be produced with minimal energy consumption and does not require any electricity in the application.
In warmer countries in particular, the filter could be used to prevent dangerous virus infections. In developing and emerging countries around 500,000 people die every year from infections with enteroviruses. The victims are often toddlers. Enteroviruses are very tough and acid-resistant, they can survive in water for a very long time. The filters could also prevent infections in the context of the corona epidemic.
via ETH Zurich