Assembling photosensitive capsules by phthalocyanines and polyelectrolytes for photodynamic therapy

A photosensitive capsule consisting of aluminum phthalocyanine tetrasulfonate chloride (AlPcS4Cl) and polyelectrolytes was fabricated by assembling of oppositely charged poly(allylamine hydrochloride) (PAH) and AlPcS4Cl onto the preformed capsules composed of poly(styrene sulfonate) (PSS) and PAH. UV–visible absorption spectra, EDX spectrum and AFM images confirmed the successful deposition of AlPcS4Cl onto as-prepared hollow capsules. The assembled photosensitive capsules were found to remain intact and spherical morphology in the deposition process. The generation of cytotoxic singlet oxygen (1O2) of photosensitive capsules under visible light irradiation (670 ± 10 nm) was evidenced by ESR measurements and the oxidative reaction between the generated 1O2 and a detector. In vitro cellular experiments showed that photosensitive capsules exhibited a good biocompatibility in the dark and a higher killing efficacy against MCF-7 cancer cells under visible light irradiation as compared with free AlPcS4Cl, which implies that the assembled photosensitive capsules might be potentially applicable in photodynamic therapy.