Photoinduced in Vivo Magnetic Resonance Imaging (MRI) with Rapid CO Release from an MnCO-Protein Needle Composite.

Construction of an artificial protein needle (PN), which includes the membrane puncturing needle domain of bacteriophage T4 conjugated to Mn carbonyl (MnCO) complexes, is reported. The responsiveness to visible light of the MnCO complex makes it useful as a photoinduced in vivo magnetic resonance imaging contrast reagent (MRI CR), because the PN carrier has the potential to deliver the MnCO complex into mouse tumors with retention of coordination structure within the in vivo environment. Moreover, the composite has higher relaxivity and longer circulation as an MRI CR than the corresponding MnCO complex. These results demonstrate construction of a responsive in vivo MRI CR by using an artificial metalloprotein.