Polyoxometalates as next-generation of theragnostic gadgets in cancer

Polyoxometalates (POMS) are a class of mineral clusters of transition metals or rare-earth elements linked together by Oxo ligands. POMs have been identified as antibacterial, antiviral, and anticancer agents after decades of research since the onset of the 20th century. Furthermore, in recent years POMs have been studied for their applications in diagnosis, photodynamic therapy, photothermal therapy, and theragnostic. However, these last-mentioned POM applications have rarely been reviewed. Considering the potential characteristic features of POMs, comprising their easy, inexpensive, and scalable synthesis, and with special attention to the challenges of their application, POMs would be great alternatives to many conventional medical tools in the field of cancer treatment and diagnosis. In this review, we report recent updated research around utilizing POMs in cancer diagnosis and theragnostic. Publications are on basic topics including POMs in magnetic resonance imaging (MRI), POMs in computed tomography (CT), POMs in cancer photoluminescence (PL) imaging, POMs in multimodality, POMs in radiation therapy applications, POMs as radiosensitizer and promotor of drug release, and POMs in theragnostic applications. It is hoped that this review paper will be useful for those researchers who are interested in expanding the applications of polyoxometalates in the field of cancer treatment and diagnosis.