Removal effect of Candida albicans biofilms from the PMMA resin surface by using a manganese oxide nanozyme-doped diatom microbubbler

To prevent oral candidiasis, removal of the Candida biofilms from dentures is important. However, common denture cleaners are insufficiently effective in removing biofilms. A manganese oxide (MnO2) nanozyme-doped diatom microbubbler (DM) can generate oxygen gas microbubbles by a catalase-mimicking activity in hydrogen peroxide (H2O2). DM can invade and destroy biofilms with the driving force of continuously generated microbubbles. In this study, the Candida biofilm removal efficiency by co-treatment of DM and H2O2 was investigated. Diatom particles were reacted with (3-aminopropyl)triethoxysilane to prepare amine-substituted diatom particles. These particles were reacted with potassium permanganate to fabricate DMs. The morphology and components of DM were analyzed by using a scanning electron microscope (SEM). Four types of denture base resin specimens on which biofilms of Candida albicans were formed were treated with phosphate-buffered saline (PBS group), Polident 5-Minute (Polident group), 0.12% chlorhexidine gluconate (CHX group), 3% H2O2 (H2O2 group), and co-treatment of 3 mg/mL of DM and 3% H2O2 (DM group). The biofilm removal effect of each group was quantitatively analyzed by crystal violet assay, and the results were visually confirmed by SEM images. After each treatment, the remaining C. albicans were stained with Hoechst 33342/propidium iodide, and observed with confocal laser scanning microscopy (CLSM) to evaluate the viability. MnO2 nanozyme sheets were successfully doped on the surface of the fabricated DM. Although biofilms were not effectively removed in the Polident and CHX groups, CLSM images showed that CHX was able to effectively kill C. albicans in the biofilms on all resin specimen types. According to the crystal violet analysis, the H2O2 groups removed the biofilms on heat-activated and 3D-printed resins (P < .01), but could not remove the biofilms on autopolymerizing and milled resins significantly (P = .1161 and P = .1401, respectively). The DM groups significantly removed C. albicans from all resin specimen types (P < .01).