New liposome-encapsulated-polyoxometalates: synthesis and antitumoral activity

Liposome-encapsulated polyoxometalates (abbreviated as LEP): incorporating K6SiW11TiO40 {(SiW11Ti) LEP} have been synthesized and structurally characterized by elemental analysis, and IR, UV-Vis, and NMR spectroscopy. The particle sizes of these complexes ranged from 15 to 60 nm. The polyoxometalate retained the parent structure after encapsulation by the liposome. Based upon in vitro measurements with KB and HeLa cancer cells, the liposome-encapsulation enhances cell-membrane penetration, and the stability and antitumoral activity of the polyoxometalate. The toxicity of the polyoxometalate was reduced when LEPs were employed against HL-60 tumors in vivo.