Silicon Nitride Inactivates SARS-CoV-2 in vitro

  1. Caitlin W. Lehman
  2. Rafaela Flur
  3. Kylene Kehn-Hall
  4. Bryan J. McEntire
  5. B. Sonny Bal
  6. Ryan M. Bock

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Abstract

Introduction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the COVID-19 pandemic, remains viable and therefore potentially infectious on several materials. One strategy to discourage the fomite-mediated spread of COVID-19 is the development of materials whose surface chemistry can spontaneously inactivate SARS-CoV-2. Silicon nitride (Si 3 N 4 ), a material used in spine fusion surgery, is one such candidate because it has been shown to inactivate several bacterial species and viral strains. This study hypothesized that contact with Si 3 N 4 would inactivate SARS-CoV-2, while mammalian cells would remain unaffected.

Materials

SARS-CoV-2 virions (2×10 4 PFU/mL diluted in growth media) were exposed to 5, 10, 15, and 20% (w/v) of an aqueous suspension of sintered Si 3 N 4 particles for durations of 1, 5, and 10 minutes, respectively. Before exposure to the virus, cytotoxicity testing of Si 3 N 4 alone was assessed in Vero cells at 24 and 48 hour post-exposure times. Following each exposure to Si 3 N 4 , the remaining infectious virus was quantitated by plaque assay.

Results

Vero cell viability increased at 5% and 10% (w/v) concentrations of Si 3 N 4 at exposure times up to 10 minutes, and there was only minimal impact on cell health and viability up to 20% (w/v). However, the SARS-CoV-2 titers were markedly reduced when exposed to all concentrations of Si 3 N 4 ; the reduction in viral titers was between 85% - 99.6%, depending on the dose and duration of exposure.

Conclusions

Si 3 N 4 was non-toxic to the Vero cells while showing strong antiviral activity against SARS-CoV-2. The viricidal effect increased with increasing concentrations of Si 3 N 4 and longer duration of exposure. Surface treatment strategies based on Si 3 N 4 may offer novel methods to discourage SARS-CoV-2 persistence and infectivity on surfaces and discourage the spread of COVID-19.

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  1. ScreenIT

    SciScore for 10.1101/2020.08.29.271015: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Experimental Models: Cell Lines
    SentencesResources
    Vero cells were inoculated with SARS-CoV-2 (MOI 0.1) to generate viral stocks.
    Vero
    suggested: CLS Cat# 605372/p622_VERO, RRID:CVCL_0059)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    We recognize that this study has limitations; a powdered form of doped-Si3N4 was used, rather than the monolithic material employed as spine implants. While this study demonstrates that this powdered form of doped-Si3N4 is an effective antiviral agent, future studies will need to show that its viricidal efficacy is retained when compounded into or coated onto other materials such as polymers, paints, metals, fabrics, or ceramics. To be truly effective, the surface hydrolysis and release kinetics of β-Si3N4’s moieties will have to be optimized for each composite material and device. Additionally, further refinement of the current composition of doped β-Si3N4 may enhance its ability to release these moieties for the benefit of mammalian cells and the destruction of pathogens. Studies are also needed to identify whether simple physical contact with Si3N4 particles, or exposure to its soluble components, or both, are necessary for the antipathogenic effects observed in the present study.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. Version published to 10.1101/2020.08.29.271015v1 on bioRxiv