Evaluation of silver nanoparticles for the prevention of SARS-CoV-2 infection in health workers: In vitro and in vivo

Abstract

SARS-CoV-2 infection in hospital areas is of a particular concern, since the close interaction between health care personnel and patients diagnosed with COVID-19, which allows virus to be easily spread between them and subsequently to their families and communities. Preventing SARS-CoV-2 infection among healthcare personnel is essential to reduce the frequency of infections and outbreaks during the pandemic considering that they work in high-risk areas. In this research, silver nanoparticles (AgNPs) were tested in vitro and shown to have an inhibitory effect on SARS-CoV-2 infection in cultured cells. Subsequently, we assess the effects of mouthwash and nose rinse with ARGOVIT® silver nanoparticles (AgNPs), in the prevention of SARS-CoV-2 contagion in health workers consider as high-risk group of acquiring the infection in the General Tijuana Hospital, Mexico, a hospital for the exclusive recruitment of patients diagnosed with COVID-19. We present a prospective randomized study of 231 participants that was carried out for 9 weeks (during the declaration of a pandemic). The "experimental" group was instructed to do mouthwash and nose rinse with the AgNPs solution; the "control" group was instructed to do mouthwashes and nose rinse in a conventional way. The incidence of SARS-CoV-2 infection was significantly lower in the "experimental" group (two participants of 114, 1.8%) compared to the "control" group (thirty-three participants of 117, 28.2%), with an 84.8% efficiency. We conclude that the mouth and nasal rinse with AgNPs helps in the prevention of SARS-CoV-2 infection in health personnel who are exposed to patients diagnosed with COVID-19.

Fig 1. Antiviral activity of AgNPs in Vero E6 cell cultures.

A. Effect of AgNPs on viability of cultured Vero cells. Serial two-fold dilutions of AgNPs were added in triplicate to the medium of Vero cells seeded in 96-well plates. Viability at 24 (white bars), 48 (grey bars) and 72 h (black bars) was checked by the MTS Cell Proliferation Assay (Promega) and calculated as described in Methods. Statistically significant differences when compared to the corresponding 100% of cell viability (by 2 way ANOVA) are indicated. *, p < 0.05; ***, p < 0.001; ****, p < 0.0001. B. Percentages of infectivity values for each AgNPs concentration. The values were normalized to those in the absence of AgNPs (medium, 100%) and fitted using a non-linear regression algorithm. IC₅₀: 50% inhibitory concentration. C. Representative SARS-CoV-2 plaque formation in presence of different dilutions of AgNPs.