Synthesis and photophysics of an octathioglycosylated zinc(II) phthalocyanine

Abstract

A water soluble zinc(II) phthalocyanine symmetrically appended with eight thioglucose units was synthesized from commercially available hexadecafluorophthalocyaninatozinc(II) by controlled nucleophilic substitution of the peripheral fluoro groups. The photophysical properties and cancer cell uptake studies of this nonhydrolyzable thioglycosylated phthalocyanine are reported. The new compound has amphiphilic character, is chemically stable, and can potentially be used as a photosensitizer in photodynamic therapy.

Figure 1

Synthesis of ZnPcGlc₈. (i) 8.5 eq. GlcAc₄SAc, K₂CO₃ in THF at 40–50 °C for three days; (ii) CH₃ONa in CH₂Cl₂/CH₃OH. The isolated yield of 1b = 72%. The α and β positions on the phthalocyanine are indicated on the starting ZnPcF₁₆.

Figure 2

UV-visible spectra of 2 μM ZnPcGlc₈ in different solvents, from a 1 mM ZnPcGlc₈ in DMSO stock solution, indicating aggregation in most solvents.

Figure 3

MDA-MB-231 cells were incubated with 50 nM ZnPcGlc₈ for 24 h, rinsed three times with PBS buffer to remove unbound dye and fixed with 4% paraformaldehyde solution. Fluorescence images were captured by exciting at 540–580 nm, magnification 20× under identical conditions. (A) Just after preparation of the fixed cells slide, and (B) 4 day after later. The contrast of each was enhanced by 40% for publication.