Silicon Nitride Inactivates SARS-CoV-2in vitro

Abstract

ABSTRACTIntroductionSevere 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 (Si3N4), 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 Si3N4would inactivate SARS-CoV-2, while mammalian cells would remain unaffected.MaterialsSARS-CoV-2 virions (2×104PFU/mL diluted in growth media) were exposed to 5, 10, 15, and 20% (w/v) of an aqueous suspension of sintered Si3N4particles for durations of 1, 5, and 10 minutes, respectively. Before exposure to the virus, cytotoxicity testing of Si3N4alone was assessed in Vero cells at 24 and 48 hour post-exposure times. Following each exposure to Si3N4, the remaining infectious virus was quantitated by plaque assay.ResultsVero cell viability increased at 5% and 10% (w/v) concentrations of Si3N4at 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 Si3N4; the reduction in viral titers was between 85% - 99.6%, depending on the dose and duration of exposure.ConclusionsSi3N4was non-toxic to the Vero cells while showing strong antiviral activity against SARS-CoV-2. The viricidal effect increased with increasing concentrations of Si3N4and longer duration of exposure. Surface treatment strategies based on Si3N4may offer novel methods to discourage SARS-CoV-2 persistence and infectivity on surfaces and discourage the spread of COVID-19.