Nanoparticles have potential biomedical applications because of their special physical properties. Multi-scale nanoparticles contrast agents are those particles that provide contrast in different scale imaging modalities. Such particles are of great interest for monitoring anti-cancer drug delivery, allowing investigations of whole body drug distribution as well as that at the microscopic level. Magnetic nanoparticles in particular have been used as contrast agents in MRI and optical techniques such as confocal microscopy and two photon fluorescence (TPF) microscopy to achieve multiple scale imaging. However, confocal microscopy has a limited optical penetration in biological tissue. Moreover, both techniques, confocal microscopy and TPF microscopy, require labelling of the biological tissue which alters the particle distribution and complicates the biological system under-investigation.