Inactivation strategies for SARS-CoV-2 on surgical masks using light-activated chemical dyes.

BACKGROUND

Methylene blue (MB) and riboflavin (RB) are light-activated dyes with demonstrated antimicrobial activity. They require no specialized equipment, making them attractive for widespread use. Due to COVID-19-related worldwide shortages of surgical masks, simple, safe, and effective decontamination methods for reusing masks have become desirable in clinical and public settings.

MATERIAL AND METHODS

We examined the decontamination of SARS-CoV-2 Beta variant on surgical masks and Revolution-Zero Environmentally Sustainable (RZES) reusable masks using these photoactivated dyes. We pre-treated surgical masks with 2 MB concentrations, 2 RB concentrations, and 2 combinations of MB and RB. We also tested 7 MB concentrations on RZES masks.

RESULTS

Photoactivated MB consistently inactivated SARS-CoV-2 at >99.9% for concentrations of 2.6 µM or higher within 30 min on RZES masks and 5 µM or higher within 5 min on disposable surgical masks. RB alone showed a lower, yet still significant inactivation (∼93-99%) in these conditions.

DISCUSSION

MB represents a cost-effective, rapid, and widely deployable decontamination method for SARS-CoV-2. The simplicity of MB formulation makes it ideal for mask pre-treatment in low-resource settings.

CONCLUSIONS

The results demonstrate that MB effectively decontaminates SARS-CoV-2 at concentrations above 5 µM on surgical masks and above 10 µM on RZES masks.