Synergistic photodynamic therapeutic effect of indole-3-acetic acid using a pH sensitive nano-carrier based on poly(aspartic acid-: Graft -imidazole)-poly(ethylene glycol)

Poly(aspartic acid-graft-imidazole)-poly(ethylene glycol) (P(Asp-g-Im)-PEG) was utilized as a pH-sensitive nanocarrier of the photosensitizer indole-3-acetic acid (IAA) for the treatment of skin cancer. IAA loaded micelles (ILMs) exhibited the formation of ca. 140 nm spherical particles at pH 7.4. The micelles disintegrated at acidic pHs, resulting in pH-dependent IAA release and cytotoxicity. Treatment of ILMs with visible light at a wavelength of 480 nm caused pH dependent synergistic cell damage in both in vitro and in vivo models using the B16F10 melanoma cell line. Interestingly, ILMs synergistically produced reactive oxygen species (ROS) at an acidic pH of 6.5 with visible light irradiation by proton coupled electron transfer (PCET). The pH sensitive ILMs could be considered a potent nanomedicine used to exert synergistic photodynamic therapeutic effects to treat cancers.