Abstract
BackgroundThe emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic during the fall of 2019 and into the spring of 2020 has led to an increased demand of disposable N95 respirators and other types of personal protective equipment (PPE) as a way to prevent virus spread and help ensure the safety of healthcare workers. The sudden demand led to rapid modification, development, and dissemination of 3D printed PPE. The goal of this study was to determine the inherent sterility and re-sterilizing ability of 3D printed PPE in order to provide sterile equipment to the healthcare field and the general public.MethodsSamples of polylactic acid (PLA), thermoplastic polyurethane (TPU) (infill-based designs) and polypropylene (single-wall hollow design) were 3D printed. Samples were inoculated with E. coli for 24 h and then sanitized using various chemical solutions or heat-based methods. The samples were then incubated for 24- or 72-h in sterile LB medium at 37°C, and bacterial growth was measured by optical density at 600nm. Statistical analysis was conducted using GraphPad Prism v8.2.1.ResultsSignificant bacterial growth was observed in all PLA and TPU based samples following re-sterilization, regardless of the methods used when compared to controls (p < 0.05). The single-walled hollow polypropylene design was not only sterile following printing, but was also able to undergo re-sanitization following bacterial inoculation, with no significant bacterial growth (p > 0.05) observed regardless of sanitization method used.ConclusionThe cost effectiveness, ease of sanitization, and reusability of 3D printed PPE, using our novel single-walled polypropylene design can help meet increased demands of PPE for healthcare workers and the general public that are needed to help decrease the viral transmission of the coronavirus disease of 2019 (COVID-19) pandemic. 3D printing also has the potential to lead to the creation and production of other sterile material items for the healthcare industry in the future. The ability to re-sterilize 3D printed PPE, as our design shows, would also contribute less to the increase in biomedical waste (BMW) being experienced by COVID-19.
Highlights
The emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic during the fall of 2019 and into the spring of 2020 has led to an increased demand of disposable N95 respirators and other types of personal protective equipment (PPE) as a way to prevent virus spread and help ensure the safety of healthcare workers
polylactic acid (PLA) cylinders sanitized using a 20-minute isopropanol sanitization protocol showed robust bacterial growth Following the printing procedures outlined in methods, PLA cylinders (Fig. 1a-c) printed with infill were sterilized using 91% isopropanol, followed by incubation at 37°C in sterile LB broth for 24 and 72 h
Quantification of growth revealed significant increases (P < 0.05) in Sanitizing of 3D printed materials following bacterial inoculation is possible for single-walled polypropylene, but not for PLA or thermoplastic polyurethane (TPU) based products In order to determine if polypropylene is a better alternative plastic for the production of 3D printed PPE, 1.25 cm square samples of single wall design 3D printed PLA, TPU, and polypropylene were inoculated overnight with E. coli, chemically sanitized, and incubated in liquid broth for 24 and 72 h (Fig. 3a-c)
Summary
The emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic during the fall of 2019 and into the spring of 2020 has led to an increased demand of disposable N95 respirators and other types of personal protective equipment (PPE) as a way to prevent virus spread and help ensure the safety of healthcare workers. The emergence of the COVID-19 pandemic during the fall of 2019 and into the spring of 2020 has led to a heightened demand of disposable PPE, including N95 respirator masks and single use disposable facemasks, as a way to prevent virus spread and help ensure the safety of healthcare workers and others who may come in contact with the virus. It has been estimated that within the United States alone, an average years’ worth of waste could be generated in just 2 m if reusability, recycling and/or policymaking measures are not put into place [9] The continued increase in the number of people infected with COVID-19, within different regions and countries around the globe, indicates the world will be overrun by COVID-waste, having a deep impact on sustainable waste management practices in the near future [5]
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