SYNOPSIS
Higher propagation of Candida biofilms may aggravate intraoral health such as periodontium, leading to unfavorable prognoses for tissue regeneration. We examined protamine and its hydrolysates to determine whether they offer the possibility of being used for antifungal activity for PMMA dental prosthesis. Candida albicans (C. albicans), a pathogenic microorganism causing oral candidiasis, was used as the target strain to evaluate antifungal activity. We also investigated surface attachment of the protamine onto PMMA and analyzed surface characterization of treated PMMA using XPS analysis. After oxygen (O₂)-plasma treatment on a PMMA surface (PMMA+O2), XPS analysis showed that the intensity ratios of O1s/C1s and C = O/C-C both became higher in that of the PMMA+O2 compared to that of untreated PMMA. On an adsorption assay using the quartz crystal microbalance with dissipation (QCM-D) technique, protamine and its hydrolysates were demonstrably more able to adhere to the PMMA+O2 sensors than to the untreated PMMA sensors. The amounts of C. albicans that initially attached to and the fungi that colonized on the PMMA and PMMA+O2 specimens were lower than on untreated PMMA (control). A tendency to decrease was noted for protamine hydrolysates compared with native protamine. These results indicated that protamine and its hydrolysates could be immobilized on PMMA surfaces, providing antifungal activity on these surfaces.

Key words: PMMA, antifungal peptide, Candida albicans, biofilm, O₂ plasma