Development of neutron-activated samarium-153-loaded polystyrene microspheres as a potential theranostic agent for hepatic radioembolization

Abstract

Purpose 

Hepatic radioembolization is an effective minimally invasive treatment for primary and metastatic liver cancers. Yttrium-90 [⁹⁰Y]-labelled resin or glass beads are typically used as the radioembolic agent for this treatment; however, these are not readily available in many countries. In this study, novel samarium-153 oxide-loaded polystyrene ([¹⁵³Sm]Sm₂O₃-PS) microspheres were developed as a potential alternative to ⁹⁰Y microspheres for hepatic radioembolization.

Methods 

The [¹⁵²Sm]Sm₂O₃-PS microspheres were synthesized using solid-in-oil-in-water solvent evaporation. The microspheres underwent neutron activation using a 1 MW open-pool research reactor to produce radioactive [¹⁵³Sm]Sm₂O₃-PS microspheres via ¹⁵²Sm(n,γ)¹⁵³Sm reaction. Physicochemical characterization, gamma spectroscopy and in-vitro radionuclide retention efficiency were carried out to evaluate the properties and stability of the microspheres before and after neutron activation.

Results 

The [¹⁵³Sm]Sm₂O₃-PS microspheres achieved specific activity of 5.04 ± 0.52 GBq·g⁻¹ after a 6 h neutron activation. Scanning electron microscopy and particle size analysis showed that the microspheres remained spherical with an average diameter of ~33 μm before and after neutron activation. No long half-life radionuclide and elemental impurities were found in the samples. The radionuclide retention efficiencies of the [¹⁵³Sm]Sm₂O₃-PS microspheres at 550 h were 99.64 ± 0.07 and 98.76 ± 1.10% when tested in saline solution and human blood plasma, respectively.

Conclusions 

A neutron-activated [¹⁵³Sm]Sm₂O₃-PS microsphere formulation was successfully developed for potential application as a theranostic agent for liver radioembolization. The microspheres achieved suitable physical properties for radioembolization and demonstrated high radionuclide retention efficiency in saline solution and human blood plasma.