Photodynamic treatment of onychomycosis using bacterial nanocellulose patches for photosensitizer delivery

: The high prevalence of onychomycosis, a common pathology of nails due to fungal infections, has drawn attention to the development of new therapeutic approaches in which systemic secondary effects and the rise of drug resistance are avoided. Photodynamic therapy (PDT) is an approach that can be useful for treatment of onychomycosis, relying on the activation of a photosensitizer with light of a specific wavelength producing cytotoxic reactive oxygen species in situ. The present work describes the use of bacterial nanocellulose (BNC) patches delivering two different photosensitizers: Rose Bengal (RB) and a BODIPY derivative (B-I2), whose differing hydrophilicity necessitated distinct formulation strategies. The experiments performed using vertical Franz cells allowed the optimization of the systems, finally tested in in vitro experiments with Candida albicans cultures. The results showed the efficacy of the BNC patches in the delivery of RB, showing that the presence of a keratolytic agent as urea is vital for the RB permeation through the nail models, with the permeation of RB being the first step for an efficient light-driven disinfection of C. albicans using green-laser light. Similar results were obtained with B-I2 although the high lipophilicity of the dye limited its cytotoxic evaluation in vitro.