Synthesis of Glutathione-Responsive Cyclomatrix Polyphosphazene for Multimodal Theranostic Nanodrug Delivery

In this work, a multimodal (chemotherapeutic/photodynamic/photothermal) theranostic nanodrug delivery platform was developed based on the synergetic action of self-framed polyphosphazene prodrug and heptamethine cyanine dye IR-780. First, an electronegative glutathione (GSH)-responsive polyphosphazene prodrug abbreviated as HGEH was prepared via multicomponent condensation reaction of genistein (GEN), bis-(4-hydroxyphenyl)-disulfide, and hexachlorocyclotriphosphazene. The particle size of drug (GEN)-containing HGEH nanoparticles is adjustable. Subsequently, cationic near-infrared photosensitizer IR-780 was adsorbed onto the electron-rich HGEH to obtain the multimodal theranostic nanodrug delivery platform HGEH-IR780. The platform was demonstrated to retain high stability in avoiding drug leakage and enable controlled drug release in response to the tumor microenvironment, in which a higher GSH concentration exists. The in vitro experiments show that HGEH-IR780 undergoes photothermal and photodynamic processes to concurrently generate heat and reactive oxygen species for efficiently killing mouse breast cancer cells (4T1) upon exposure to a single-bandwidth near-infrared laser (808 nm). Specifically, HGEH-IR780 inhibits 4T1 cells by up to 80% at a concentration of 100 μg/mL. The as-developed HGEH-IR780 exhibits promising results in GSH-responsive anticancer activity and photodynamic/photothermal therapy, which provides a reference for the construction of the polyphenol flavonoid multimodal therapeutic nanoplatform.