Lanthanide Metal-Organic Frameworks for Multispectral Radioluminescent Imaging.

: In this report, we describe the X-ray luminescent properties of two lanthanide-based, nanoscale metal-frameworks (nMOFs) and their potential as novel material platforms for optical molecular imaging techniques such as, X-ray excited radiolumine-scence imaging. Upon X-ray irradiation, the nMOFs display sharp, tunable emission peaks that span the visible to near-infrared spectral region (~400-700 nm), based on the identiy of the metal (Eu, Tb, or Eu/Tb). Surface modification of the nMOFs with polyethylene glycol resulted in nanoparticles with enhanced aqueous stability that demonstrated both cyto- and hemo-compatibility, important prerequisites for biological applications. Importantly, this is the first report to document and investigate the radioluminescent properties of lanthanide nMOFs. Taken together, the observed radioluminescent properties and low in vitro toxicity demonstrated by the nMOFs render them promising candidates for in vivo translation.