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The in vitro retention of both parents and daughters results suggests that LaPO4 NPs are potentially effective carriers of radium isotopes.

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Gadolinium vanadate (GdVO4) core and core + 2 shell nanocrystals (NCs) were evaluated for in vitro retention of 225Ac, 227Th, and their first decay daughters, 221Fr and 223Ra, respectively. GdVO4 NCs with a tetragonal crystal system (zircon-type) and spherical morphology were obtained by precipitation of GdCl3 and Na3VO4 using sodium citrate as a complexing agent. The growth of two nonradioactive GdVO4 shells on both Gd(225Ac)VO4 and Gd(227Th)VO4 core NCs was demonstrated by an increase of 0.7 nm and 2 nm in the crystallite size, respectively. The maximum leakage of 225Ac was 15% and 2.4% from core and core + 2 shells, whereas the leakage of 227Th was 3% and 1.5%, respectively. The presence of two nonradioactive GdVO4 shells increased the retention of 221Fr and 223Ra by 20% and 15% with respect to core NCs. Furthermore, a longitudinal proton relaxivity, r1 = 0.9289 s−1 mM−1, confirmed their potential application as contrast agents for magnetic resonance imaging. In summary, GdVO4 NCs show promising capabilities as radionuclide carriers with partial retention of decay daughters and as contrast agents for theranostic applications.

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Development of actinium-225 doped Gd0.8Eu0.2VO4 core–shell nanoparticles as multifunctional platforms for multimodal molecular imaging and targeted radionuclide therapy.

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Unwanted targeting of healthy organs caused by the relocation of radionuclides from the target site has been one of the limiting factors in the widespread application of targeted alpha therapy in patient regimens. GdVO4 nanoparticles (NPs) were developed as platforms to encapsulate α-emitting radionuclides 223Ra, 225Ac, and 227Th, and retain their decay daughters at the target site. Polycrystalline GdVO4 NPs with different morphologies and a zircon-type tetragonal crystal structure were obtained by precipitation of GdCl3 and Na3VO4 in aqueous media at room temperature. The ability of GdVO4 crystals to host multivalent ions was initially assessed using La, Cs, Bi, Ba, and Pb as surrogates of the radionuclides under investigation. A decrease in Ba encapsulation was obtained after increasing the concentration of surrogate ions, whereas the encapsulation of La cations in GdVO4 NPs was quantitative (∼100%). Retention of radionuclides was assessed in vitro by dialyzing the radioactive GdVO4 NPs against deionized water. While 227Th was quantitatively encapsulated (100%), a partial encapsulation of 223Ra (∼75%) and 225Ac (>60%) was observed in GdVO4 NPs. The maximum leakage of 221Fr (1st decay daughter of 225Ac) was 55.4 ± 3.6%, whereas for 223Ra (1st decay daughter of 227Th) the maximum leakage was 73.0 ± 4.0%. These results show the potential of GdVO4 NPs as platforms of α-emitting radionuclides for their application in targeted alpha therapy.