Effect of 5-aminolevulinic acid photodynamic therapy on Candida albicans biofilms: An in vitro study

- Photodynamic therapy has shown great promise for the inactivation of Candida species. However, the effectiveness of ALA-PDT against biofilm-associated Candida albicans remains poorly documented.
- Our study revealed for the first time that protoporphyrin IX (PpIX), the real photosensitizer can be absorbed in biofilm-grown C.albicans.
- Our results showed that under appropriate parameters, photochemistry can be triggered by light in combination with ALA and eliminates Candida albicans effectively.

BackgroundIn this study, the photoinactivation of 5-aminolevulinic acid (ALA) has been investigated on Candida albicans biofilms in vitro.MethodsAfter culture and proliferation of Candida albicans biofilms in vitro, the metabolic activity was confirmed using XTT reduction assay. Then, the suitable incubation time and concentration of ALA were determined by measuring PpIX accumulation quantities. Photosensitivity of the biofilms treated with ALA solution was studied in optical doses of 50, 100, 200 and 300 J/cm2 while light irradiation was applied by a red light semiconductor. Finally, rapid immunofluorescence staining method using the LIVE/DEAD FungaLight Yeast Viability Kit and XTT assay were conducted to visualize and quantify the antifungal effect of ALA-PDT on Candida albicans biofilms.ResultsA 5 h incubation time and 15 mM ALA concentration were determined for this study. Photoinactivation of ALA-PDT on Candida albicans biofilms showed a significant increase of protoporphyrin IX (PpIX) in the biofilms. The metabolic activity of Candida albicans biofilms tread with ALA-PDT confirmed the inhibition efficacy compared with control groups. Upon radiation at 300 J/cm2, cells in Candida albicans biofilms were 74.45% inhibited.ConclusionsPpIX can be absorbed in biofilm-grown Candida albicans in vitro and under appropriate parameters, photochemistry can be triggered by light in combination with ALA and inhibits Candida albicans biofilms effectively.