Filter utilizing whey protein nanofibrils and iron oxyhydroxides nanoparticles catches viruses, together with SARS-CoV-2

A latest Swiss examine posted to the bioRxiv* preprint server demonstrated that aerosol filters centered on granular protein nanofibrils and iron (Fe) oxyhydroxides nanoparticles may lure virus-containing aerosols. 

Research: Trapping virus-loaded aerosols utilizing granular protein nanofibrils and iron oxyhydroxides nanoparticles. Picture Credit score: Dotted Yeti / Shutterstock


As a primary line of protection in opposition to viral outbreaks and pandemics, non-pharmaceutical measures are essential.

Utilizing air filters has quite a few advantages over different non-pharmaceutical measures in opposition to coronavirus illness 2019 (COVID-19), like masks mandates and social distancing. They result in retaining indoor area capacities, offering a cost-effective different for inadequately ventilated rooms, and are much less delicate to particular person decisions or behavioral self-discipline.

The gold commonplace for aerosol filtering is high-efficiency particulate air (HEPA) filters. World deployment of HEPA filters to stop the unfold of airborne viruses in indoor environments will come at exorbitant monetary and environmental prices.

Total, halting the transmission of airborne viruses has been fairly difficult, and this issue will increase if it needs to be achieved globally and sustainably.

In regards to the examine

Within the present analysis, the scientists created an aerosol filter composed of granular filtration materials counting on Fe oxyhydroxide nanoparticles and amyloid nanofibrils (AF), i.e., AF-Fe, adopting a easy manufacturing process.

The AF was synthesized by reducing the pH to 2 and boiling whey protein extract, a spinoff of the dairy trade, at 90 °C for about 5 hours. The chemical properties of the AF-Fe materials had been confirmed using Fourier remodel infrared spectroscopy. Moreover, mercury intrusion porosimetry was used to research the intra-particle pore-size distribution of the fabric.

The authors designed and constructed a small experimental setup to check the fabric’s filtration potential. On this setup, virus-loaded aerosols had been produced, handed by way of the AF-Fe at a move price of seven.5 l/min, after which captured on a gelatin membrane that entraps ≥99% of passing viruses whereas retaining their infectiousness. The filtration capability of AF-Fe was assessed by contrasting the infectious viruses captured on the gelatin membranes with and with out AF-Fe.

The researchers examined the affect of reducing the quantity of AF-Fe on the strain drop and filtration efficiencies. Following filtering aerosols containing bacteriophage MS2 or Φ6, they incubated the AF-Fe for about an hour in phosphate-buffered saline (PBS) buffer to judge the fabric’s security. In addition to, the investigators modeled 4 of essentially the most vital aerosol entrapment processes to deeply analyze how the AF-Fe traps aerosols: diffusion, interception, gravitational settling, and impaction.


The examine outcomes depicted that the AF-Fe materials was environmental-friendly, biodegradable, and made up of a dairy sector byproduct. In keeping with sieve evaluation, it has a large measurement vary, with half of its mass lower than 3 mm.

Fourier remodel infrared spectroscopy confirmed three peaks for amide teams, representing the amyloid fibrils, and one of many Fe-O-H group, symbolizing the Fe oxyhydroxides nanoparticles. The AF-Fe materials had a excessive particular floor space, 44.1 m2/g, i.e., half of the floor protection potential of 1 g of AF-Fe was roughly 3 * 1012 and seven * 1014 for 150 or 30 nm virus particles, respectively. As well as, its particular density, ρs, was 2.1 g/cm3, and bulk densities of the oven-dried and air-equilibrated samples had been 1.4 and 1.7 g/cm3, respectively, demonstrating a fairly excessive intra-particle porosity of 30% and a volumetric water content material of 36%.

The AF-Fe materials had pores in measurement between tens and hundreds of nanometers, in line with mercury intrusion porosimetry. The dimensions vary of those pores enabled them to behave as virus-trapping cavities as soon as the viruses hooked up themselves to the AF-Fe floor.

The AF-Fe had a mean filtering effectivity of 95.91% and 99.87% in opposition to extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and H1N1, respectively. Each had been enveloped viruses and had been identified to be airborne. For a non-enveloped enterovirus acknowledged for its stability and resilience to harsh chemical situations, EV71, AF-Fe has a filtration effectiveness of 99%. The common filtering effectivity for bacteriophage Φ6 was 99.99%, whereas for bacteriophage MS2 was 98.29%.

Surprisingly, the filtration effectiveness was accompanied by a negligible strain drop, i.e., <0.03 bar, throughout the fabric, suggesting AF-Fe would use little power to function. The workforce found that lowering the strain drop to round 0.02 bar whereas using as little as two-thirds of the fabric utilized within the reported exams had little to no affect on AF-Fe’s filtering effectivity. 

After passing by way of AF-Fe, the ratio of infectious SARS-CoV-2 and H1N1 to the entire genome rely diminished, proving that the viruses had been confined and partly inactivated. However, EV71 didn’t exhibit such inactivation, corroborating that non-enveloped viruses had been extra resistant and sturdy to mechanical stresses from AF-Fe interactions and the re-aerosolization process.

Since no infectious viruses had been recovered, the authors famous that AF-Fe totally rendered bacteriophage Φ6 inactive or irrevocably trapped the virus. Additional, <0.5% of the infectious MS2 viruses had been recovered, indicating a notable potential of AF-Fe for entrapping the virus irreversibly. Furthermore, MS2 was solely inactivated to beneath the detection vary when AF-Fe was baked at 60 ˚C for one hour. The authors additionally talked about that the AF-Fe may have aerosol entrapment processes akin to fiber-based filters.


Collectively, the examine findings confirmed that AF-Fe filtered virus-loaded aerosols with excessive effectivity whereas additionally being eco-friendly and sustainable. As well as, the fabric had an astonishingly minimal strain drop, suggesting low power and working prices.

Moreover, the contaminated materials was secure to deal with and has considerably greater recycling potential than the industrial filters out there available on the market. The workforce envisages the fabric being utilized to mitigate the airborne viruses unfold worldwide with out just about inflicting an environmental footprint. The current examine’s utilization of granular materials for aerosol filtration is anticipated to encourage researchers to search for native, novel, environment-friendly supplies that would function the inspiration for aerosol filters.

*Essential discover

bioRxiv publishes preliminary scientific experiences that aren’t peer-reviewed and, due to this fact, shouldn’t be thought to be conclusive, information scientific observe/health-related habits, or handled as established info.

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