Chemo–Phototherapeutic Effect of Polyoxometalate-Stabilized Gold Nanostars for Cancer Treatment

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