The photodynamic antimicrobial chemotherapy activities of azaBODIPY dyes and their gold nanoparticle conjugates

This synthesis and photophysicochemical properties of two 2,6-diiodinated azaBODIPY dyes with thiomethylphenyl groups at the distal positions and phenyl (1) and naphthyl (2) rings at the proximal positions are reported. The dyes were conjugated to gold nanoparticles (1-AuNPs and 2-AuNPs) to enhance their aqueous solubility for biomedical applications. Iodination at the 2,6-positions resulted in an enhancement of singlet oxygen generation, with singlet oxygen quantum yield (Φ_∆) values of 0.82 and 0.55 obtained in DMSO for 1 and 2, respectively. The photodynamic antimicrobial chemotherapy (PACT) activities of the dyes were tested with a Thorlabs M660L3 light-emitting diode (LED) against Staphylococcus aureus after incubation at 5 µM. Conjugation to gold nanoparticles was found to significantly enhance the PACT activities against Staphylococcus aureus. Log₁₀ reduction values of 8.94 were obtained for 1-AuNPs after 30 min irradiation (3.0 J.cm^-2) and 2-AuNPs after 60 min (6.0 J.cm^-2).