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Photodynamic therapy (PDT) is a highly specific and clinically approved method for cancer treatment in which a nontoxic drug known as photosensitizer (PS) is administered to a patient. After selective tumor irradiation, an almost complete eradication of the tumor can be reached as a consequence of reactive oxygen species (ROS) generation, which not only damage tumor cells, but also lead to tumor-associated vasculature occlusion and the induction of an immune response. Despite exhaustive investigation and encouraging results, zinc(II) phthalocyanines (ZnPcs) have not been approved as PSs for clinical use yet. This review presents an overview on the physicochemical properties of ZnPcs and biological results obtained both in vitro and in more complex models, such as 3D cell cultures, chicken chorioallantoic membranes and tumor-bearing mice. Cell death pathways induced after PDT treatment with ZnPcs are discussed in each case. Finally, combined therapeutic strategies including ZnPcs and the currently available clinical trials are mentioned.

The use of Zn-phthalocyanine in a red-light-driven process for the perfluoroalkylation reactions of (hetero)arenes and sufides represents a friendlier environmental alternative.

A major difficulty in photodynamic therapy is the poor solubility of the photosensitizer (PS) under physiological conditions which correlates with low bioavailability. PS aggregation leads to a decrease in the photodynamic efficiency and a more limited activity in vitro and in vivo. To improve the aqueous solubility and reduce the aggregation of 2,9(10),16(17),23(24)-tetrakis[(2-dimethylamino)ethylsulfanyl]phthal-ocyaninatozinc(II) (Pc9), the encapsulation into four poloxamine polymeric micelles (T304, T904, T1107 and T1307) displaying a broad spectrum of molecular weight and hydrophilic-lipophilic balance was investigated. The aqueous solubility of Pc9 was increased up to 30 times. Morphological evaluation showed the formation of Pc9-loaded spherical micelles in the nanosize range. UV/Vis and fluorescence studies indicated that Pc9 is less aggregated upon encapsulation in comparison with Pc9 in water-DMSO 2% and remained photostable. Pc9-loaded micelles generated singlet molecular oxygen in high yields. Photocytotoxicity assays using human nasopharynx KB carcinoma cells confirmed that the encapsulation of Pc9 in T1107 and T1307 increases its photocytotoxicity by 10 times in comparison with the free form in water-DMSO. In addition, Pc9 incorporated into cells was mainly localized in lysosomes.

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