Rapid Inactivation of mixed biofilms of Candida albicans and Candida tropicalis using antibacterial photodynamic therapy: Based on PAD™ Plus

Lifang Zhang; Qiaoyu Hu; Ying Zhang; Yanan Wang; Na Liu; Qing Liu

doi:10.1016/j.heliyon.2023.e15396

Rapid Inactivation of mixed biofilms of Candida albicans and Candida tropicalis using antibacterial photodynamic therapy: Based on PAD™ Plus

Heliyon. 2023 Apr 10;9(4):e15396. doi: 10.1016/j.heliyon.2023.e15396. eCollection 2023 Apr.

Authors

Lifang Zhang¹, Qiaoyu Hu¹, Ying Zhang¹, Yanan Wang¹, Na Liu², Qing Liu¹

Affiliations

¹ Hebei Key Laboratory of Stomatology, Hebei Clinical Research Center for Oral Diseases, School and Hospital of Stomatology, Hebei Medical University, Shijiazhuang, 050017, PR China.
² Department of Preventive Dentistry, School and Hospital of Stomatology, Hebei Medical University, Shijiazhuang, 050017, PR China.

Abstract

Background: To investigate the sterilizing effect of antimicrobial photodynamic therapy (aPDT) based on PAD™ Plus on mixed biofilms of Candida albicans and Candida tropicalis.

Methods: A mature mixed biofilm model of C. albicans and C. tropicalis was constructed in vitro. FITC-concanavalin A staining was conducted to observe the formation of the extracellular matrix. MTT assay was performed to determine biofilm viability. The chromogenic medium was used to examine the Candida composition of the mixed biofilms. For aPDT treatment, based on PAD™ Plus, the biofilms were incubated with 1 mg/mL TBO for 1, 5, or 10 min, followed by 500 or 750 mW LED illumination for 1 or 2 min. The live/dead fungi were detected by SYTO9/propidium iodide staining. A multivariate factorial design was conducted to analyze the correlations of parameters with the inactivation effect of the mixed biofilms.

Results: Mature mixed biofilms formed at 24 h after seeding. Compared with untreated biofilms, following 1-min TBO incubation, 500 mW LED illumination for 1 min inactivated more than 90% of the fungi. Extending the incubation time did not significantly improve the inactivation effect. Application of 750 mW output power or 2 min LED illumination inactivated more than 99% of the fungi without increasing other parameters.

Conclusions: PAD™ Plus combined with 1 mg/mL TBO can rapidly inactivate the mature mixed biofilms of C. albicans and C. tropicalis, serving as a robust platform for the treatment of mixed infections of C. albicans and C. tropicalis.

Keywords: Antimicrobial photodynamic therapy; Biofilms; Candida albicans; Candida tropicalis; Toluidine blue O.