Non-aggregated lipophilic water-soluble tin porphyrins as photosensitizers for photodynamic therapy and photodynamic antimicrobial chemotherapy

Abstract

Two readily synthesized water-soluble Sn(IV) porphyrins have been prepared with quaternized pyridyl nitrogens and 2-naphthalato trans-axial ligands. Methyl and hexyl groups were attached to the quaternized nitrogens to form lipophilic dyes with high singlet oxygen quantum yields (ca. 0.90) and unusually long triplet state lifetimes. The dyes exhibit good photodynamic activity against MCF-7 cells with IC₅₀ values of 14.3 and 8.5 μM, respectively. The hexyl quaternized dye exhibited a 9.69 log reduction value (0.5 μM) towards S. aureus under illumination for 90 min (250 mW cm⁻²). The results demonstrate that this set of structural modification strategies for photosensitizer dyes merits further in depth study.