Prussian Blue Nanoparticles and Their Potential for the Treatment of Internal 137Cs Contamination in Mice

Radiological emergencies, such as nuclear power plant accidents or the detonation of radiation-dispersive devices, can release radionuclides into the environment, with Cesium-137 (137Cs) of particular concern due to its long half-life (30.17 years), high water solubility, and widespread dispersibility. Once incorporated, 137Cs distributes in soft tissues and exhibits a long biological half-life. The approved commercial countermeasure for internal decorporation is Radiogardase®-Cs, the insoluble Prussian Blue (PB; ferric hexacyanoferrate(II)), which binds radiocesium and thallium in the gastrointestinal tract. Since absorption occurs mainly in the small intestine and redistribution via enterohepatic circulation prolongs retention, effective decorporation strategies remain essential. In this study, insoluble PB nanoparticles were synthesized via an optimized indirect route employing hydrogen peroxide treatment, and their structure characteristics were compared to those of Radiogardase®-Cs, followed using an in vivo C57Bl6 mouse model for acute internal 137Cs decorporation assessment. Initially, the elimination kinetics for the ingestion of 137Cs was assessed using control animals. The results revealed a decrease of half of the radionuclides' initial activity within a period of approximately 3.4 days. Following therapeutic effect tests of 1-to-4-day treatment of contaminated mice with Nano-PB formulation indicated by 1.2- to 1.9-fold higher excretion rate of 137Cs compared to that when Radiogardase®-Cs was used. Although the short-term elimination profiles of Nano-PB and Radiogardase®-C appeared comparable, the overall results for the nanosized particles indicated an advantage in enhanced radiocesium decorporation. This effect may be attributed to the higher density of active binding sites, enhancing binding efficiency, while future perspectives should include comparison of absorption capacity and comprehensive toxicity assessments of the nanosized PB formulations.