Radiosensitising nanoparticles as novel cancer therapeutics--pipe dream or realistic prospect?

The field of high atomic number nanoparticle radiosensitising agents is reviewed. After a brief discussion of the new mode of physicochemical action implied by irradiation of high atomic number nanoparticles embedded in biological systems, a series of exemplars are discussed. Silver-, gadolinium- and gold-based nanoparticles are discussed in order of increasing atomic number with functionalisation strategies being outlined. In vitro and in vivo evidence for radio-enhancement and the mechanisms attributed to the increased biological effect are discussed.