Antifungal effects of methylene blue–mediated photodynamic therapy and 808-nm laser against Candida albicans: an in vitro pilot study

Aims: This study aimed to evaluate the antifungal effects of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT), alone and in combination with simultaneous 808 nm diode laser irradiation on Candida albicans (C. albicans) colonies. Methods: This pilot study was designed as an exploratory in vitro investigation based on qualitative assessment without quantitative or statistical analysis. C. albicans (ATCC 10231) suspensions were homogeneously spread onto Sabouraud Dextrose Agar plates. MB was applied at concentrations ranging from 0.01% to 1%. aPDT was performed using a 630 nm LED for durations of 10 s, 30 s, 1 min, and 2 min. In a separate experimental setup, the simultaneous application of aPDT and an 808 nm diode laser was evaluated. The inhibitory effects on C. albicans growth were visually assessed and compared with control groups.Results: Qualitative visual assessment showed that MB alone demonstrated concentration-dependent antifungal activity, with complete inhibition observed in the 1%. aPDT with MB ≥0.1% eliminated colony formation after 1–2 minutes of irradiation. In the 0.03% and 0.02% groups, aPDT alone did not produce a clear inhibition zone, although growth density decreased after 2 minutes. In the combined treatment (aPDT+808 nm laser), efficacy was markedly enhanced. Specifically, in the 0.03% group, where aPDT alone was limited, the addition of the laser resulted in clear inhibition zones.Conclusion: The simultaneous application of aPDT and 808 nm laser resulted in enhanced inhibition of C. albicans. The addition of the diode laser improved antifungal efficacy, enabling effective inhibition at lower MB concentrations (0.03%), where aPDT alone was insufficient.