Print Email Facebook Twitter Lanthanopolyoxometalate-Silica Core/Shell Nanoparticles as Potential MRI Contrast Agents Title Lanthanopolyoxometalate-Silica Core/Shell Nanoparticles as Potential MRI Contrast Agents Author Carvalho, Rui F.S. (Universidade de Coimbra) Pereira, Giovannia A.L. (Universidade de Coimbra; Federal University of Pernambuco; University of Aveiro) Rocha, João (University of Aveiro) Castro, M. Margarida C.A. (Universidade de Coimbra) Granadeiro, Carlos M. (Universidade do Porto; University of Aveiro) Nogueira, Helena I.S. (University of Aveiro) Peters, J.A. (TU Delft BT/Biocatalysis) Geraldes, Carlos F.G.C. (Universidade de Coimbra) Date 2021 Abstract The NMR relaxivities of the decatungstolanthanoate core-shell nanoparticles, prepared by encapsulating [Ln(W5O18)2]9− polyoxometalates (LnPOM) within amorphous silica shells (K9[Ln(W5O18)2]@SiO2), were studied along the Ln series. The relaxivity of GdPOM is slightly higher than for Gd-DTPA due to second-sphere relaxation effects, but the values for the other paramagnetic LnPOMs are much smaller due to the short T1e values of their Ln3+-ions. The NPs have core-shell spherical structures, with LnPOM-containing cores with 9.5–28 nm diameters, and 4.0–11.0 nm thick amorphous silica shells. In water suspensions, the NPs have negative zeta potentials (−32.5 to −40.0 mV) and time-dependent hydrodynamic diameters (31–195 nm) reflecting the formation of aggregates. The relaxivities of GdPOM@SiO2 NPs suspensions (r1=10.97 (mM Gd)−1 s−1, r2=12.02 (mM Gd)−1 s−1, 0.47 T, 25 °C) are considerably larger than for the GdPOM solutions, indicating that their silica shell is significantly porous to water. This increase is limited by the agglomeration of the complexes in the NPs core, limiting their access to water to those at the core surface. Replacing half of the Gd3+ ions by Eu3+ decreases the NPs r1 and r2 relaxivities at 0.47 T to 20 % and 35 % of their initial values, which are still considerable, but does not affect the efficient luminescence properties of the Eu3+ centers. This indicates that the mixed NPs have potential as dual modality MRI/optical imaging contrast agents. Subject Contrast agentsCore-shell nanoparticlesLanthanidesParamagnetic relaxationPolyoxometalates To reference this document use: http://resolver.tudelft.nl/uuid:b0dba1d0-7b25-4dc7-81b4-0ec05744d347 DOI https://doi.org/10.1002/ejic.202100445 Embargo date 2022-07-22 ISSN 1434-1948 Source European Journal of Inorganic Chemistry, 2021 (34), 3458-3465 Bibliographical note Accepted Author Manuscript Part of collection Institutional Repository Document type journal article Rights © 2021 Rui F.S. Carvalho, Giovannia A.L. Pereira, João Rocha, M. Margarida C.A. Castro, Carlos M. Granadeiro, Helena I.S. Nogueira, J.A. Peters, Carlos F.G.C. Geraldes Files PDF LnPOM_silica_CAs_EurJIC_final.pdf 1.25 MB Close viewer /islandora/object/uuid:b0dba1d0-7b25-4dc7-81b4-0ec05744d347/datastream/OBJ/view