High-intensity Ultraviolet-C irradiation sterilization data

The sterilization effect of high intensity ultraviolet-C (HIUVC) against SARS-CoV-2 and Staphylococcus aureus (S.aureus) under 4 °C and -20 °C are presented in the file. Medical gauze was selected as carrier for SARS-CoV-2 and S.aureus. The samples were exposed to HIUVC at the irradiance of 5.1 mW/cm2 for 1 s, 3 s and 5 s, respectively. Each experiment of different conditions was repeated 3 times to assure the repeatability.SARS-CoV-2 isolate (nCoV-2019BetaCoV/Wuhan/WIV04/2019) was obtained from Wuhan Institute of Virology, Chinese Academy of Sciences. The virus sterilization experiment was conducted in biosafety level-3 (BSL-3) laboratory in National Biosafety Laboratory, Wuhan. The virus was propagated in Vero E6 cells cultured in Dulbecco’s modified Eagle’s medium (DMEM, Gibco) supplemented with 10% fetal bovine serum (FBS, Gibco). On day 2 post-infection, the culture supernatant was harvested and filtered for virus stocks and tittered through plaque assay. Medical gauze was selected as carrier for microorganism contamination. The size of the carrier is 2.0×2.0 cm with one layer, which was sterilized by 121 °C steam and dried before it was inoculated with the microorganism.A drip of 200 μL SARS-CoV-2 (1.33 ×107 pfu/ml) was dropped on the gauze in a 35 mm dish (Thermo Fisher Scientific). The inoculum was absorbed into the material as it was absorbent. The samples were kept in refrigerator of 4 °C and -20 °C for 30 minutes before HIUVC exposure, separately. Then, the 4 °C and -20 °C samples were put on precooled ice storage plate. Immediately, the samples were exposed to HIUVC at the irradiance of 5.1 mW/cm2 for 1 s, 3 s and 5 s, respectively. The control group was put in dark place. Subsequently, virus samples were transferred aseptically to centrifuge tube of 50 mL. Remaining virus in the dish was eluted with 2 ml DMEM, and transferred to the centrifuge tube mentioned above. The tube was whirled in vortex mixer with maximum speed of 5 s/time for five times. The virus titer was determined by plaque assay. The experiments were conducted in triplicates.The S.aureus sterilization experiment was conducted in Test Center of Antimicrobial Materials, Technical Institute of Physics and Chemistry. S.aureus suspension was made by inoculating S.aureus from activated tryptic soy agar plate medium into solution containing nutrient broth, saline and Tween. Then the suspension was serially diluted into approximate 106~107 pfu/ml solution. A drip of 75 μL S.aureus (ATCC 6538) containing 3% bovine serum albumin was dropped on the gauze. Subsequently, the samples were treated with the same temperature and HIUVC irradiation condition as those contaminated with SARS-CoV-2. After irradiation, samples of S.aureus were assayed by standard pour plate procedures. The samples were massaged with 10 mL 0.03 M phosphate-buffered saline (pH 7.4) and serially diluted with sterile saline solution. Molten plate count agar was poured into petri dish containing 1 mL of diluted sample. The solid medium was incubated at 37 °C for 24 hours for plate count.