Abstract:
Novel chloroindium(III) complexes of tetra(4-methylthiophenyl)porphyrin (2a) and tetra-
2-thienylporphyrin (2b) dyes have been synthesized and characterized. The main goal of the project was
to identify fully symmetric porphyrin dyes with Q-band regions that lie partially in the therapeutic window
that are suitable for use in photodynamic therapy (PDT). 2a and 2b were found to have fluorescence
quantum yield values ≤ 0.01 and moderately high singlet oxygen quantum yields (0.54−0.73) due to heavy
atom effects associated with the sulfur and indium atoms. The dark toxicity and PDT activity against
epithelial breast cancer cells (MCF-7) were investigated over a dose range of 3.0−40 mg . mL-1. The
in vitro dark cytotoxicity of 2a is significantly lower than that of 2b at ≤ 40 mg . mL-1. 2a was conjugated
with gold nanoparticles (AuNPs) to form a nanoconjugate (2a-AuNPs), which exhibited a higher singlet
oxygen quantum yield (FD) value and PDT activity than was observed for 2a alone. The results suggest
that the AuNPs nanoconjugates of readily synthesized fully symmetric porphyrin dyes are potentially
suitable for PDT applications, if meso-aryl substituents that provide scope for nanoparticle conjugation
can be introduced that shift the Q bands into the therapeutic window.
