Formation of gold decorated porphyrin nanoparticles and evaluation of their photothermal and photodynamic activity

• Core-shell PF6-Au nanoparticles were prepared through a graft-copolymer-based micelle with photosensitization and photothermic behavior.
• PF6 was placed in the core of the nanoparticles through molecular self-assembly. Au nanoparticles were decorated on this 60-nm-diameter shell.
• Core-shell PF6-Au nanoparticles demonstrated effective singlet oxygen production and heat generation upon irradiation.

A core-shell gold (Au) nanoparticle with improved photosensitization have been successfully fabricated using Au nanoparticles and 5,10,15,20 tetrakis pentafluorophenyl)-21H,23H-porphine (PF6) dye, forming a dyad through molecular self-assembly. Au nanoparticles were decorated on the shell and PF6 was placed in the core of the nanoparticles. Highly stable Au nanoparticles were achieved using PF6 with poly(N-vinylcaprolactam-co-N-vinylimidazole)-g-poly(d,l-lactide) graft copolymer hybridization. This was compared with hybridization using cetyltrimethylammonium bromide and polyethylene glycol-b-poly(d,l-lactide) for shell formation with PF6–Au. The resulting PF6-poly(N-vinylcaprolactam-co-N-vinylimidazole)-g-poly(d,l-lactide)-Au core–shell nanoparticle were utilized for photothermal and photodynamic activities. The spectroscopic analysis and zeta potential values of micelles revealed the presence of a thin Au layer coated on the PF6 nanoparticle surface, which generally enhanced the thermal stability of the gold nanoparticles and the photothermal effect of the shell. The core–shell PF6–Au nanoparticles were avidly taken up by cells and demonstrated cellular phototoxicity upon irradiation with 300 W halogen lamps. The structural arrangement of PF6 dyes in the core–shell particles assures the effectiveness of singlet oxygen production. The study verifies that PF6 particles when companied with Au nanoparticles as PF6–Au have possible combinational applications in photodynamic and photothermal therapies for cancer cells because of their high production of singlet oxygen and heat.

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