The COVID-19 pandemic drove a huge demand for disposable face coverings, like face masks.1 While an important tool against the spread of the virus, these are typically made of synthetic polymers like polypropylene.1,2 When disposed of into the environment, polypropylene breaks down into microplastics, contaminating soil and water.
What’s more, it can persist in the environment for up to 450 years.3,4 Polypropylene-based personal protective equipment (PPE) also lacks antibacterial or antiviral properties, meaning microbes can contaminate its surface and lead to infection.2 Therefore, there is an imperative to develop more sustainable PPE that also provides improved protection against viruses like SARS-CoV-2.2
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Cellulose fibers, which are both strong and biodegradable, provide one of the most suitable sources for these materials, as they can be derived from fast-growing and abundant plants like hemp.1 In a recent study, researchers led by Huining Xiao at the University of New Brunswick, Canada, explored the development of antibacterial and antiviral cellulose nonwovens (CNWs) for use in PPE.2
Biodegradable Cellulose Nonwovens: A Sustainable Solution to Microplastic Pollution
The team bonded several molecules to the surface of the CNWs, including a guanidine-based polymer, PHMG, known to have strong antibacterial and antiviral properties, and the aminoglycoside antibiotic neomycin sulfate (NEO). For some of the samples they tested, they also performed a chemical reaction to render the surface of the nonwoven hydrophobic, overcoming its natural hydrophilic state. The team then used a range of analytical methods to confirm the successful bonding of these compounds to the cellulose surface. For example, using a Bruker VERTEX80v Fourier transform infrared spectrometer, they confirmed the covalent bonding of certain chemical groups to the cellulose surface. Employing Bruker NMR technology, the team also used newly detected NMR signals on the modified nonwoven to confirm the presence of expected chemical groups in the bonded molecules. Other tests included X-Ray photoelectron spectroscopy, elemental analysis, and hydrophilicity/hydrophobicity.2
The team then tested the antibacterial and antiviral properties of the modified CNWs. They first studied the effect of the modified CNWs on E. coli and S. aureus. They found that for both PHMG- and NEO-bonded CNWs, inhibitory effects on bacterial growth were greater with the non-hydrophobic samples during short-term exposure. However, after 60 minutes, all samples showed close to 100% inhibition of both bacteria. Importantly, the team then demonstrated the samples’ efficacy against two strains of coronavirus: the COVID-19-related SARS-CoV-2 and the less virulent HCoV-229E human coronavirus. Both PHMG- and NEO-bonded non-hydrophobic CNWs showed effective inactivation of both viruses. This was most pronounced for SARS-CoV-2, which began rapid inactivation within moments of contact. After 30 minutes of exposure, near-complete inactivation of SARS-CoV-2 was seen for both modified CNWs.2
To summarize their findings, the team was successful in its endeavor to create highly effective antiviral/antibacterial components on surfaces of cellulose nonwoven fabric via unique covalent linkages. The end result was a multi-functional, biodegradable, and breathable nonwoven layer for PPE-related materials. As noted in the Journal of Hazardous Materials, the researchers say this is the first time that a modified nonwoven has been shown to instantly inactivate SARS-CoV-2, demonstrating its potential to substitute conventional non-biodegradable layers in PPE. The team also illustrated that its modified CNWs maintained air permeability and filtration properties, indicating they would be suitable for use in face masks. As such, damaging PP-based facemasks can now potentially be replaced by the team’s cellulose-based biodegradable and self-cleaning ones, significantly reducing microplastic/nanoplastic pollution and easing the pollution caused by the COVID-19 pandemic. However, future applications are likely to expand beyond masks, finding further uses in packaging, hospital textiles, and high-efficiency particulate air filters in transportation.2
References and Further Reading
- Filipova I, Irbe I, Spade M, et al. Mechanical and Air Permeability Performance of Novel Biobased Materials from Fungal Hyphae and Cellulose Fibers. Materials 2021;14:136.
- Deng C, Seidi F, Yong Q, et al. Antiviral/antibacterial biodegradable cellulose nonwovens as environmentally friendly and bioprotective materials with potential to minimize microplastic pollution. J Hazard Mater. 2022;424(Pt A):127391.
- Nghiem LD, Iqbal HMN, Zdarta J. The shadow pandemic of single use personal protective equipment plastic waste: A blue print for suppression and eradication. Case Stud Chem Environ Engineering 2021;4:100125.
- Deng C, Seidi F, Yong Q, et al. Virucidal and biodegradable specialty cellulose nonwovens as personal protective equipment against COVID-19 pandemic. J Adv Res. 2022;39:147-156.
This information has been sourced, reviewed and adapted from materials provided by Bruker BioSpin - NMR, EPR and Imaging.
For more information on this source, please visit Bruker BioSpin - NMR, EPR and Imaging.