Application Analysis of (124)I-PPMN for Enhanced Retention in Tumors of Prostate Cancer Xenograft Mice

BACKGROUND: In recent years, nuclear medicine imaging and therapy for prostate cancer have radically changed through the introduction of radiolabeled prostate-specific membrane antigen (PSMA)-binding peptides. However, these small molecular probes have some inherent limitations, including high nephrotoxicity and short circulation time, which limits their utility in biological systems. METHODS AND RESULTS: In this study, organic melanin nanoparticles were used to directly label the long half-life radionuclide (124)I (t(1/2)=100.8 h), and PSMA small molecular groups were efficiently bonded on the surface of nanoparticles to construct the PSMA-targeted long-retention nanoprobe (124)I-PPMN, which has the potential to increase tumor uptake and prolong residence time. The results showed that the nanoprobe could substantially aggregate in the tumors of prostate cancer xenograft mice and was visible for more than 72 h. Positron Emission Computed Tomography (PET) imaging showed that the nanoprobe could be used for precise imaging of prostate cancer with high expression of PSMA. In addition, organic melanin nanoparticles labeled with an elemental radionuclide achieved a stable, metal-free structure. Cell experiments and mouse toxicity experiments indicated that the nanoprobe has high safety. CONCLUSION: The new nanoprobe constructed in this study has high specificity and biocompatibility. In the future, combined with the multifunctional potential of melanin nanoparticles, this nanoprobe is expected to be used in the integrated theranostics of prostate cancer.