Chemo–Phototherapeutic\nEffect of Polyoxometalate-Stabilized\nGold Nanostars for Cancer Treatment

A reduced polyoxometalate (POM) functionalized with bisphosphonate\n(BP) ligands possessing antitumoral properties was used to synthesize\nmetallic gold nanostars (AuNSs) with high reproducibility through\na silver-assisted seed growth method. Notably, this study is the first\nto employ a reduced polyoxometalate as a dual-function reducing and\ncapping agent in the synthesis of gold nanostars. The resulting AuNS@POM\ncomposites, characterized by a plasmon band located at 744 nm, combine\nin a single hybrid nanocomposite alendronate ligands, Mo­(VI) ions,\nand Au<sup>0</sup> centers. The colloidal stability of AuNS@POM was\ndemonstrated in a biological culture medium, and cell experiments\nwere performed to study its antitumoral activity on U87 and MCF7 cell\nlines from glioblastoma and liver cancer, respectively. First, it\nwas established that the antitumoral activity of the BP POM is enhanced\ndue to the Mo­(V) to Mo­(VI) oxidation process that occurs during AuNS\nformation. Second, it has been shown that in the presence of the composite,\ncellular metabolic activity decreases drastically under the effect\nof irradiation at 808 nm, even leading to almost complete cell death.\nAuNS@POM therefore exhibits strong antitumor chemo–photothermal\nactivity, paving the way for the development of a type of dual therapeutic\nagent operating under near-infrared irradiation.