The Electrostatic‐Mediated Formation of a Coordination Complex: the Trapping and Release of an Antitumor Drug with an Anthracycline Core from {Mo72Fe30}‐Based Ensembles

This article studies the binding of the antitumor drug doxorubicin (DOX) with the nanocluster polyoxometalate (POM) {Mo72Fe30}, the latter serving as the drug carrier. The formation of a stoichiometric complex POM@(DOX)12 was observed in aqueous media. Using the Stern‐Volmer technique, we found the binding constant and free Gibbs energy for this interaction. The produced complex POM@(DOX)12 was examined with ultraviolet‐visible (UV‐Vis), fluorescence (steady state and life‐time), infrared (IR) and X‐ray photoelectron spectroscopy (XPS), which revealed the stoichiometry of complex and a key role of {Mo3Fe3} host pores on the POM surface to DOX binding. DOX's ability to intercalate into DNA after binding with the {Mo72Fe30} was investigated using a pH typical for blood (7.4). A pH‐dependent release of DOX from POM@(DOX)12 was demonstrated (rate constant is 3.3×10−4 s−1). Finally, we showed that the immobilization of doxorubicin on the POM's surface can reduce undesired side effects. The coordination of the Keplerate‐type nanocluster polyoxometalate {Mo72Fe30} with the antitumor drug, doxorubicin (DOX), makes possible the pH‐control of its DNA‐intercalation. The produced {Mo72Fe30}@DOX can be applied for treatment to decrease the side effects.