Liquid gallium has been used to produce an antiviral and antimicrobial coating by an international research team. The coating was tested on a variety of fabrics, such as facemasks.
Image Credit: North Carolina State University
The coating bound more powerfully to fabrics than some traditional metal coatings and eliminated 99% of various common pathogens within 5 minutes.
Microbes can survive on the fabrics hospitals use for bedding, clothing and face masks for a long time. Metallic surface coatings such as copper or silver are an effective way to eradicate these pathogens, but many metal particle coating technologies have issues such as non-uniformity, processing complexity, or poor adhesion.
Michael Dickey, Study Co-Corresponding Author and Camille & Henry Dreyfus Professor of Chemical and Biomolecular Engineering, North Carolina State University
Dickey and the team from NC State, Sungkyunkwan University (SKKU) in Korea, and RMIT University in Australia endeavored to create a simple, cost-effective method to deposit metal coatings on fabrics.
Initially, the researchers added liquid gallium (Ga) to an ethanol solution and used sound waves to create Ga nanoparticles. This process is called sonication. The nanoparticle solution was then spray coated onto the fabric and Ga bound to the fibers as the ethanol evapourated.
The researchers then immersed the Ga-coated fabric into a copper sulfate solution, which led to the immediate galvanic replacement reaction. The reaction tends to deposit copper onto the fabric, producing a coating of liquid metal copper alloy nanoparticles.
The researchers verified the antimicrobial characteristics of the coated fabrics by exposing the fabric to three common microbes, namely, Staphylococcus aureus, Escherichia coli and Candida albicans.
The microbes tend to grow strongly on non-coated fabrics. Eventually, 99% of the pathogens were killed within 5 minutes by the copper alloy coated fabric. This was remarkably more effective compared to the control samples with only copper.
The researchers joined hands with Elisa Crisci, assistant professor of virology at NC State, and Frank Scholle, associate professor of biological sciences at NC State, to demonstrate that the coatings also repel viruses. The coating was also subjected to tests against human influenza (H1N1) and coronavirus (HCoV 229E), which belong to the same family as SARS-CoV-2. Those viruses were killed after 5 minutes of the application of the coating.
Our tests indicate that these liquid metal-copper coated fabrics demonstrate superior antimicrobial performance compared to other copper coated surfaces and two commercial antimicrobial facemasks that rely on copper and silver respectively.
Vi Khanh Truong, Vice Chancellor’s Postdoctoral Fellow, RMIT University
Vi Khanh Truong is also a visiting Fulbright Scholar at RMIT University and the co-corresponding author of the study. According to Yoon Kwon, a postdoctoral associate at SKKU and study first author, “This is a better method for generating metal coatings of fabrics, particularly for antimicrobial applications, both in terms of adhesion and antimicrobial performance.”
It could also work with metals other than copper, such as silver. It is also a simple method, which should be relatively straightforward to scale up for mass production.
Tae-il Kim, Study Co-Corresponding Author and Professor, Sungkyunkwan University
Journal Reference:
Kwon, K. Y., et al. (2021) A Liquid Metal Mediated Metallic Coating for Antimicrobial and Antiviral Fabrics. Advanced Materials. doi.org/10.1002/adma.202104298.