Abstract: 【Abstract】 Objective To assess antimicrobial activity of Fe3O4 nanozymes against Candida albicans. Methods Fe3O4 nanozymes were prepared by using a modified hydrothermal synthesis method. Candida albicans suspensions were divided into 4 groups: nanozyme group treated with 0.5 g/L Fe3O4 nanozymes, H2O2 group treated with 0.1% H2O2 , combination group treated with 0.5 g/L Fe3O4 nanozymes and 0.1% H2O2 , and control group receiving no treatment. Candida albicans in the above 4 groups was all cultured with Sabouraud liquid medium, the absorbance （A value） at 600 nm was detected every 2 hours, and the growth of Candida albicans was observed. After 2-hour treatment, the morphology of Candida albicans in the 4 groups was observed by scanning electron microscopy; after plate coating, Candida albicans was cultured at 36 ℃ for 48 hours, colonies were observed and counted, and the inhibition rate of colony formation was calculated. One-way analysis of variance was used for comparing means among several groups, and least significant difference （LSD）-t test for multiple comparisons. Results A relatively stable survival curve of Candida albicans was observed in the control group, while the growth of Candida albicans was inhibited in the nanozyme group, H2O2 group and combination group. The colony count significantly differed among the control group, H2O2 group, nanozyme group and combination group （124 830 ± 45 170, 86 330 ± 13 960, 91 670 ± 31 370 and 30 330 ± 3010 respectively; F = 9.41, P < 0.05）, and was significantly lower in the combination group than in the control group （t = 4.63, P < 0.05）. There was a significant difference in the antimicrobial rate among the H2O2 group, nanozyme group and combination group （30.84% ± 5.00%, 26.57% ± 11.24%, 75.70% ± 2.42% respectively; F = 9.413, P < 0.01）, and the combination group showed a significantly higher inhibition rate of colony formation compared with the H2O2 group and nanozyme group （t = 8.08, 4.27 respectively, both P < 0.01）. Scanning electron microscopy showed changes in the morphology of Candida albicans treated with H2O2 and nanozymes alone or in combination, including shrinkage, rupture and even collapse. Conclusion Fe3O4 nanozymes combined with H2O2 have obvious antimicrobial effect against Candida albicans.

Key words: Candidiasis, Candida albicans, Hydrogen peroxide, Catalase, Magnetite nanoparticles, Ferumoxytol