Figure 4

Investigation of the biosafety and storage stability of TA-HF. (a,b) Cell viability assay to assess the cytotoxicity of TA-HF (n = 3) before (a) and after influenza virus capture (b). (c,d) Influenza virus capture efficiency of TA-HFs, which were freshly prepared and stored for one or two months at − 20 °C, 4 °C, or 25 °C, to determine the storage stability of TA-HF. Red dotted lines indicate initial virus-capture capacity of TA-HF. (e) Influenza virus capture efficiency of TA-HFs for a period of three weeks placed in indoor environment (ID) and inside an air purifier environment (AP). TA tannic acid, HF high-efficiency particulate air filter.