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Dissertation
The development, evaluation, and field validation of biocide functionalized nanofiber material for the application of disposable personal protective equipment
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Autumn 2024
DOI: 10.25820/etd.007590
Abstract
Disposable personal protective equipment (PPE) such as surgical masks and protective clothing is not designed to be antimicrobial and requires decontamination for reuse. In this work, we aimed to improve protections for workers in biosecurity settings (e.g., livestock facilities) and minimize disease transmission from contaminated personal protective equipment (PPE) for healthcare workers by developing, evaluating, and field validating nanofiber materials with antimicrobial properties for use in PPE.
First, we fabricated polystyrene nanofibers (PS) functionalized with biocides including silver nanoparticles (AgNPs) in two sizes (20 and 35 nm) and a quaternary ammonium compound tetrabutylammonium bromide (TBAB) at 0.1 wt.% and 1 wt.% either individually or combined, via electrospinning. We investigated their antimicrobial efficacy by exposing these nanofiber layers to bioaerosols containing either Escherichia coli (E. coli) or bacteriophage MS2 for 15 minutes then evaluating their antibacterial/antiviral efficacy after an additional 10-, 60-, 120-, and 180-minute of contact time. We identified that the PS based formulation containing 1 wt.% AgNPs (20 nm) and 1 wt.% TBA20B achieved the highest antibacterial and antiviral efficacy after 120-minute contact time as compared to the conventional materials used in a Tyvek® laboratory coat and surgical mask, as well as nonfunctionalized PS.
Second, we fabricated the same formulation from a 1.5 mL and a 0.3 mL precursor solution to make relatively thick and thin nanofiber layers, respectively, exposed these thick and thin nanofiber layers repeatedly to two different loadings of bioaerosols containing either E. coli (1.8 × 1010 and 5.8 × 107 CFU/mL) or bacteriophage MS2 (8.7 × 1013 and 1.7 × 109 PFU/mL) for a 15 minute exposure duration followed with 120 minute contact time, and then evaluated their antibacterial and antiviral efficacy. We found that both thick and thin nanofiber layers sustained more than 3 additional log-units reduction relative to a polypropylene surgical mask when exposed to bioaerosols containing 5.8 × 107 CFU/mL of viable E. coli repeatedly for 10 repeated exposure periods. The same nanofiber layers also sustained 3 - log units of additional reduction relative to the material used in a N-95 respirator when exposed to bioaerosols containing 8.7 × 1013 PFU/mL viable bacteriophage MS2 repeatedly for seven repeated exposure periods. Furthermore, we found that the thick nanofiber layers were more efficacious against repeated exposures to bacteriophage MS2 than that of thin nanofiber layers.
Finally, using the same methodology as we used in the laboratory, we tested the antimicrobial efficacy of the thick and thin nanofiber layers at a swine production facility. When repeatedly exposed to bioaerosols at the swine production facility for up to 15 exposure periods, we found that both thick and thin nanofiber layers eliminated E. coli growth and sustained more than 3-log units of additional reduction relative to a polypropylene surgical mask and an unfunctionalized PS nanofiber layer. In fact, overall, performance at the swine production facility matched expectations from laboratory studies.
Collectively, our data suggests that our biocide-functionalized nanofibers may be suitable for either extended use or reuse as self-decontaminating material for PPE development. The outcome of this study may help to further protect workers in biosecurity settings and reduce disease transmission from contaminated PPE for healthcare workers.
Details
- Title: Subtitle
- The development, evaluation, and field validation of biocide functionalized nanofiber material for the application of disposable personal protective equipment
- Creators
- Michelle Wei
- Contributors
- David M Cwiertny (Advisor)Matthew W Nonnenmann (Advisor)Jong Sung Kim (Committee Member)Patrick T O'Shaughnessy (Committee Member)Peter S Thorne (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Human Toxicology
- Date degree season
- Autumn 2024
- DOI
- 10.25820/etd.007590
- Publisher
- University of Iowa
- Number of pages
- xvi, 170 pages
- Copyright
- Copyright 2024 Michelle Wei
- Language
- English
- Date submitted
- 12/05/2024
- Description illustrations
- illustrations, graphs, tables
- Description bibliographic
- Includes bibliographical references (pages 144-170).
- Public Abstract (ETD)
- Disposable personal protective equipment (PPE), such as face masks, acts as a barrier between the wearer and infectious materials. A limitation for PPE is that PPE materials are not designed to kill disease causing organisms known as pathogens. This raises concerns for proper PPE use, removal, disposal, and the need to decontaminate for reuse to minimize disease transmission from touching contaminated PPE. In this work, well-known germ-killing substances, including small silver particles and a common hand wipe ingredient quaternary ammonium compound tetrabutylammonium bromide, were incorporated into thin plastic polymer fiber mats with diameters less than 1/100 of human hair. These materials were tested against airborne particles containing surrogate pathogens to determine how much pathogens were killed on these materials. One of the materials not only killed a minimum of 99.9% of pathogens but also effectively repelled water, which is a desirable property for PPE as a liquid barrier. The same material was then tested against high and low loadings of pathogens repeatedly. It was discovered these materials could be reused at least three times without the need of decontamination. The same material was then tested in a swine production facility and showed similarly effective to results in the laboratory, killing a minimum of 99.9% of bacteria in a real-world application setting. The innovative materials made herein may be suitable for use in future PPE to kill pathogens and reduce disease transmission to users, increasing work safety relative to conventional materials used to make laboratory coats and face masks.
- Academic Unit
- Interdisciplinary Graduate Program in Human Toxicology
- Record Identifier
- 9984774960302771
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