All-Inorganic Polyoxometalates Act as Superchaotropic Membrane Carriers

Polyoxometalates (POMs) are known antitumoral, antibacterial, antiviral, and anticancer agents and considered as next-generation metallodrugs. Herein, a new biological functionality in neutral physiological media, where selected mixed-metal POMs are sufficiently stable and able to affect membrane transport of impermeable, hydrophilic, and cationic peptides (heptaarginine, heptalysine, protamine, and polyarginine) is reported. The uptake is observed in both, model membranes as well as cells, and attributed to the superchaotropic properties of the polyoxoanions. In view of the structural diversity of POMs these findings pave the way toward their biomedical application in drug delivery or for cell-biological uptake studies with biological effector molecules or staining agents.