Supramolecular and base-induced singlet oxygen generation enhancement of a water-soluble phthalocyanine

Abstract

Investigation into the reactive oxygen species (ROS) generating abilities of photosensitizers outside of in-vitro/vivo conditions is a crucial element in the wider study of photodynamic therapy (PDT) in clinical settings. Zinc (II) phthalocyanine tetrasulfonic acid (ZnPcTS) is a water-soluble photosensitizer that can generate ROS as singlet oxygen (SO) under irradiation in the red and far-red region of the electromagnetic spectrum. The incorporation of ZnPcTS into nano-fibers of a bis-imidazolium hydrogel was demonstrated and the material was characterized with photophysical, rheological, and microscopy techniques. This supramolecular material containing ZnPcTS (named ZnPcTS_nEqBase@ Gels) was found to significantly enhance the SO generation rate with respect to that of ZnPcTS in an aqueous solution. The effect is attributed mainly to reduced aggregation within the gel microenvironment compared with a