Methods: Suspensions and biofilms of Candida species were incubated with P1 and P2 concentrations (0.25~50 μM) for 30 min followed by 532nm laser irradiation. For planktonic suspensions, viability of cells was assayed by CFU counting. For biofilms, the metabolic activity was evaluated by XTT. Results: In PDI of a planktonic culture of clinical fluconazole–resistant Candida albicans, P2 showed the higher efficacy. After incubation with 25 μM of P2 for 30 min and irradiation with 532nm laser (36 J cm-2), the viability of C. albicans planktonic cells decreased by 3.84 log10. For biofilm cells, a higher light dose of 75 mW cm-2 was necessary to achieve 97.71% metabolic activity reduction.
Conclusions: The results of this investigation demonstrated that benzylidene cyclopentanone photosensitizer（P2）is an efficient photosensitizer to kill C. albicans. Moreover, single-species biofilms were less susceptible to PDT than their planktonic counterparts.