Radioiodinated Portable Albumin Binder as a Versatile Agent for in Vivo Imaging with Single-Photon Emission Computed Tomography.

In this study, radioiodinated 4-( p-iodophenyl)butyric acid ([131I]IBA) was synthesized and evaluated as a portable albumin-binder for potential applications in single photon emission computed tomography imaging of blood pool, tumor, and lymph node with significantly improved pharmacokinetic properties. The [131I]IBA was prepared under the catalyst of Cu2O/1,10-phenanthroline. After that, the albumin-binding capability of [131I]IBA was tested in vitro, ex vivo, and in vivo, respectively. [131I]IBA was obtained with very high radiolabeling yield (>99%) and good radiochemical purity (>98%) within 10 min. It binds to albumin effectively with high affinity (IC50= 46.5 μM) and has good stability. The results of biodistribution indicated that the [131I]IBA was mainly accumulated in blood with good retention (10.51 ± 2.58%ID/g at 30 min p.i. and 4.63 ± 0.17%ID/g at 4 h p.i.). In the SPECT imaging of mice models with [131I]IBA, blood pool, lymph node, and tumors could be imaged clearly with high target-to-background ratio. Overall, the radioiodinated albumin binder of [131I]IBA with long blood half-life and excellent stability could be used to decorate diversified albumin-binding radioligands and developed as a versatile theranostic agent.