Exploiting biosynthetic gold nanoparticles for improving the aqueous solubility of metal-free phthalocyanine as biocompatible PDT agent.

Increasing the limit of dispersion of metal-free phthalocyanine (HPc) in an aqueous medium using biosynthetic gold nanoparticles for photodynamic therapy (PDT) is investigated. Gold nanoparticles (Au NPs) are biosynthesized in one step using Potatoes (Solanum tuberosum) extract and are characterized by UV/VIS spectrophotometry, Fourier transformer infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The metal-free phthalocyanine is conjugated to the surface of the gold nanoparticles in a side to side regime through the secondary amine groups of HPc. The clear violet solution of phthalocyanine-gold (Pc-Au) nanoconjugates is investigated by UV-VIS, FTIR and TEM techniques. Disappearance of the absorption band of the secondary amine in the Pc-Au nanoconjugates compared to that of the parent HPc, and detection of the absorption band of HPc in the aqueous medium confirmed the dispersion of HPc and consequently the loading of HPc on the surface of Au NPs. The cytotoxic effect of biosynthetic gold nanoparticles and Pc-Au nanoconjugates compared to chemically synthesized gold nanoparticles on buffalo epithelial cells has been studied in vitro. Interestingly, the results showed that the biosynthetic Au NPs as well as Pc-Au nanoconjugates have no effect on buffalo epithelial cells viability, which indicating their biocompatibility contrary to the chemically synthesized Au NPs. This work will open the door, for the first time, for using HPc suspended in water for PDT and other phototherapeutic applications.