Salt coatings functionalize inert membranes into high-performing filters against infectious respiratory diseases

Ilaria Rubino, Euna Oh, Sumin Han, Sana Kaleem, Alex Hornig, Su Hwa Lee, Hae Ji Kang, Dong Hun Lee, Ki Back Chu, Surjith Kumaran, Sarah Armstrong, Romani Lalani, Shivanjali Choudhry, Chun Il Kim, Fu Shi Quan, Byeonghwa Jeon, Hyo Jick Choi

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Respiratory protection is key in infection prevention of airborne diseases, as highlighted by the COVID-19 pandemic for instance. Conventional technologies have several drawbacks (i.e., cross-infection risk, filtration efficiency improvements limited by difficulty in breathing, and no safe reusability), which have yet to be addressed in a single device. Here, we report the development of a filter overcoming the major technical challenges of respiratory protective devices. Large-pore membranes, offering high breathability but low bacteria capture, were functionalized to have a uniform salt layer on the fibers. The salt-functionalized membranes achieved high filtration efficiency as opposed to the bare membrane, with differences of up to 48%, while maintaining high breathability (> 60% increase compared to commercial surgical masks even for the thickest salt filters tested). The salt-functionalized filters quickly killed Gram-positive and Gram-negative bacteria aerosols in vitro, with CFU reductions observed as early as within 5 min, and in vivo by causing structural damage due to salt recrystallization. The salt coatings retained the pathogen inactivation capability at harsh environmental conditions (37 °C and a relative humidity of 70%, 80% and 90%). Combination of these properties in one filter will lead to the production of an effective device, comprehensibly mitigating infection transmission globally.

Original languageEnglish (US)
Article number13875
JournalScientific reports
Issue number1
StatePublished - Aug 17 2020

Bibliographical note

Funding Information:
The authors wish to thank Mr. Ankit Kumar at the University of Alberta for technical assistance on the SEM/ EDX, and Ms. Sally Fung, Ms. Iryna Roever and Ms. Miyoung Park at the University of Alberta for assistance in the sample preparation. This research was financially supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant, University of Alberta Faculty of Engineering, and Mitacs Globalink Research Award.

Publisher Copyright:
© 2020, The Author(s).


  • Aerosols
  • Air Filters/microbiology
  • Anti-Bacterial Agents/chemistry
  • Betacoronavirus
  • COVID-19
  • Coronavirus Infections/prevention & control
  • Crystallization
  • Gram-Negative Bacteria/drug effects
  • Gram-Positive Bacteria/drug effects
  • Hot Temperature
  • Humans
  • Humidity
  • Masks/microbiology
  • Membranes, Artificial
  • Pandemics/prevention & control
  • Pneumonia, Viral/prevention & control
  • Respiratory Protective Devices/microbiology
  • SARS-CoV-2
  • Sodium Chloride/chemistry

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't


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