The aim of this study is to compare antimicrobial photodynamic therapy (aPDT) against Candida albicans biofilms formed on two different substrates - acrylic resin or bottom of polystyrene plate; and two aPDT application regimens – twice-daily over the course of 48 h or single treatment after 48 h biofilm formation. C. albicans SN425 biofilms cultivated on Roswell Park Memorial Institute medium were incubated for 5 min with toluidine blue O (44 μM) used as a photosensitizer before red light (635 nm; 175.2 J/cm²) exposure for 2 min. As negative control, ultrapure water, and as positive control 0.12% chlorhexidine (CHX) were used. Biofilms were analyzed for colony forming units (CFU) and cells morphology by confocal scanning laser microscopy. Single treatment and twice-daily aPDT on polystyrene plate and single treatment on acrylic resin did not significantly reduce the CFU (p > 0.05); in contrast, twice-daily aPDT on acrylic resin has reduced C. albicans below the detection limit, similarly to CHX treatment. Single aPDT treatment on polystyrene plate and on the resin presented a bulky and homogeneous biofilm predominantly formed by pseudohyphae. In contrast, in the resin group, the biofilm treated twice-daily with aPDT was predominantly formed by yeast cells, whilst pseudohyphae were occasionally visible. In conclusion, biofilms formed on polystyrene plates are more resistant to aPDT than biofilms formed on acrylic resin. Moreover, applying aPDT twice-daily reduces C. albicans biofilm development on acrylic resin and is a better approach against C. albicans biofilms than one single application on the mature biofilm.

本研究的目的是比较抗微生物光动力疗法 (aPDT) 与在两种不同基材上形成的白色念珠菌生物膜 - 丙烯酸树脂或聚苯乙烯板底部；和两种 aPDT 应用方案——在 48 小时内每天两次或在 48 小时生物膜形成后进行单次治疗。在 Roswell Park Memorial Institute 培养基上培养的白色念珠菌SN425 生物膜与用作光敏剂的甲苯胺蓝 O (44 μM) 在红光 (635 nm; 175.2 J/cm ²) 曝光 2 分钟。使用超纯水作为阴性对照，使用 0.12% 氯己定 (CHX) 作为阳性对照。通过共聚焦扫描激光显微镜分析生物膜的集落形成单位 (CFU) 和细胞形态。聚苯乙烯板单次处理和每日两次 aPDT 和丙烯酸树脂单次处理未显着降低 CFU（p  > 0.05）；相比之下，丙烯酸树脂上每天两次的 aPDT 减少了白色念珠菌低于检测限，类似于 CHX 处理。聚苯乙烯板和树脂上的单一 aPDT 处理呈现出主要由假菌丝形成的庞大且均匀的生物膜。相比之下，在树脂组中，每天两次用 aPDT 处理的生物膜主要由酵母细胞形成，而假菌丝偶尔可见。总之，在聚苯乙烯板上形成的生物膜比在丙烯酸树脂上形成的生物膜更能抵抗 aPDT。此外，每天两次应用 aPDT 可减少丙烯酸树脂上白色念珠菌生物膜的发展，并且是一种比在成熟生物膜上单次应用更好的方法来对抗白色念珠菌生物膜。