8A). When the biofilms were maintained in contact with
the Cur for 5 and 20 min of incubation, brighter fluorescence was observed after 20 min of incubation ( Fig. 7B, D and F), suggesting that Cur penetration into the cells of the biofilm after 20 min might have achieved greater amounts than after 5 min. The drugs need to effectively penetrate the extracellular matrix to ensure the occurrence of intimate contact with the microorganisms. For these reasons, in all the P+L+ groups, 20 min of PIT promoted the highest PF-01367338 supplier reductions in cell viability. C. albicans seemed to be the only species whose cell viabilities were clearly dependent on PIT after 4 and 8 min of irradiation. The C. albicans biofilms submitted to PDT showed higher reduction in cell viability after 20 min of PIT (p < 0.01). When PIT was reduced, cell viability was also reduced proportionally. Cell viability of C. dubliniensis biofilms after 8 min of irradiation was PIT-dependent. However, C. dubliniensis biofilms after 4 min Rigosertib datasheet of irradiation, and C. glabrata biofilms (after 4 and 8 min of irradiation) showed no clear tendency to be PIT-dependent, although 1 and 20 min of
PIT, respectively, resulted in the worst and best results. The morphology of the microorganisms seems to have great importance in PDT. A survey by Jackson et al. 26 evaluated whether the hyphae and yeasts forms of C. albicans could be killed by PDT. The results demonstrated that both forms are susceptible to photosensitisation. However, hyphal forms presented Ureohydrolase higher susceptibility to PDT than the yeasts. In the present study, the biofilms were grown in RPMI 1640, which induces hyphae formation. 19C. albicans and C dubliniensis are dimorphic fungi (ovoid yeasts and/or filaments). 12, 18 and 52 On the other hand, C. glabrata presents itself as a single
morphological species and does not transform itself into hyphae. 53 Therefore, considering the possibility that within each PIT, Cur is able to reach the same depth in the biofilms of the three species, fungi that were transformed into hyphae and were sensitised with Cur might have been more susceptible to the phototoxic effects of PDT. This might justify the fact that C. glabrata was the only species that did not present a clear tendency to be PIT-dependent under any of the evaluated conditions. Due to structural and biological differences, different behaviours are expected from distinct Candida strains. C. glabrata produces adhesins capable of promoting adhesion to buccal epithelial cells. 18 It also has high hydrophobicity values and efficient co-adhesion mechanisms, which allows cells to bind to other cells. 54 In addition, the C. glabrata biofilm matrix has higher amounts of both proteins and carbohydrates. 53 Thus, it is possible that drug penetration through the C.