Sterilization and drug susceptibility study of Candida Albicans biofilm on denture base resin treated by direct and alternating current atmospheric pressure cold plasma microjet

Summary form only given. Since early 1980s, the incidence of invasive and opportunistic mycoses has significantly increased, resulting in excessive mortality and morbidity. As a species of fungi and one of the major oral pathogens, Candida Albicans can get adhered to prosthesis and easily lead to denture stomatitis, which is a common recurring disease observed in 67% of otherwise healthy denture wearers. At present, the main treatment for denture stomatitis is pharmacotherapy and physical method. However, resistance to antifungal agents is so common that it always resulted in treatment failure. As a promising technology, cold plasma has drawn much interest in biomedical field. A few studies have indicated that cold plasma might be an efficient treatment for mycosis. Accordingly, in this study, we applied cold plasma to oral Candida Albicans biofilm and explore its potential effect on denture stomatitis. Direct current and alternating current cold PMJs were employed to treat the Candida Albicans biofilm formed on denture base resin for 1, 2, 4, 6, 8 minutes with different working gases. Scanning electron microscope (SEM) was employed to observe the morphology change and results showed that evident cell rupture was observed in experimental groups compared with control groups. By using CFU counting method, it was observed that the biofilm can be killed completely in 8min in four plasma groups. Introcellular protein (ICP) was measured with BCA protein assay reagent and the results indicated that the protein concentration of treated groups dropped remarkably over the prolonged treatment, which suggested that the mechanism underlying the sterilization phenomenon was strongly associated with protein loss. Besides, drug susceptibility was evaluated by using amphotericin B and fluconazole as antifungal drug. Results suggested that strains treated with plasma showed a higher sensitivity to antifungal drugs when compared with control groups; and the IC50 dropped significantly for each treating group over the prolonged treatment. In conclusion, AC and DC driven plasma alone or assisted with drug therapy can provide a valuable tool for Candida Albicans infection, and it will be helpful for protecting denture based resin from denture stomatitis.