Development and evaluation of nanocomposite vaginal rings for photodynamic therapy against Candida albicans

Antimicrobial photodynamic therapy (aPDT) is based on oxidative photochemical reactions and can be used against vulvovaginal candidiasis (VVC), caused by Candida albicans. This can be achieved by incorporating phthalocyanine (PC) into a polymer-matrix nanocomposite based on nanostructured lipid carriers (NLC) ureasil-polyether (UPEO), which allows them to be molded into a vaginal ring. The aim was to evaluate the aPDT of PC-NLC-UPEO rings against C. albicans. DLS and NTA showed values for NLC and PC-NLC within the nanocomposite's ideal range for pharmacological purposes. Microscopic analysis showed that NLC and PC-NLC have a spherical shape and PC-NLC-UPEO may promote better adhesion and drug release based on the roughness shown. NLC-UPEO and PC-NLC-UPEO were 0° of contact angle, demonstrating total wettability. The FTIR spectra showed no suppression of the characteristic groups of the materials and no new bands appeared. TG showed an improvement in the thermal stability of NLC when dispersed in UPEO. DTA revealed endothermic events near 100 °C related to solvent loss and dehydration. The PC released from PC-UPEO and PC-NLC-UPEO, around 37.8 % and 39.4 % were released within 24 h, which can promote initial antifungal activity. In the colony count method, PC and PC-NLC showed a reduction of 99 % in the analyses with light. Agar diffusion assay revealed halos of 7 and 15 mm in the groups with light, PC-UPEO, and PC-NLC-UPEO, respectively, demonstrating improved PC activity. The results highlight the potential of vaginal rings associated with aPDT to be administered to treat C. albicans.