Self-assembly of Gd3+-bound keplerate polyanions into nanoparticles as a route for the synthesis of positive MRI contrast agents. Impact of the structure on the magnetic relaxivity
| Autor: | Julia Elistratova, Irek R. Nizameev, Vladimir S. Korenev, Aidar T. Gubaidullin, Bulat Akhmadeev, Alexandra D. Voloshina, Asiya R. Mustafina, Maxim N. Sokolov |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
Aqueous solution Nanoparticle 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 0104 chemical sciences Hydrophilic coating Colloid Crystallography Copolymer Chemical stability Self-assembly 0210 nano-technology Stoichiometry |
| Zdroj: | Soft Matter. 14:7916-7925 |
| ISSN: | 1744-6848 1744-683X |
| DOI: | 10.1039/c8sm01214h |
| Popis: | The present work introduces Gd3+ complexes with giant keplerate polyanions as a promising basis for MRI contrast agents. The impact of Gd3+ binding with different building blocks of keplerates on the magnetic relaxivity of the complexes is revealed by comparative study of the keplerates [{Mo6O21}12{Mo2O4(OAc)}30]42−, [{Mo6O21}12{Mo2O4(HPO4)}30]72−, and [{Mo6O21}12{Mo2O2S2(OAc)}30]42−. Unprecedentedly high longitudinal and transverse relaxivity values (up to 250 and 300 mM−1 s−1 correspondingly) are achieved for the keplerates possessing edl{Mo2O4(OAc)} and {Mo2O4(HPO42−)} moieties under their 1 : 1 complex formation with Gd3+. The transformation of the external pores from Mo9O9 to Mo9O6S3 in the {Mo2O2S2(OAc)}-keplerate and an increase in the Gd3+-to-keplerate ratio are the factors that decrease the relaxivity. The rapid degradation of the free keplerates in aqueous solutions restricts the use of the Gd3+-bound keplerates with 1 : 1 stoichiometry as MRI contrast agents. In this work, the optimized stoichiometry of the complexes, their self-assembly into ultra-small nanoparticles and their hydrophilic coating by a triblock copolymer are highlighted as tools for increasing both the colloid and chemical stability of the keplerate complexes. Optimal keplerate compositions have been identified to achieve a compromise of low cytotoxicity and high stability; these Gd3+-bound keplerates exhibit longitudinal and transverse relaxivity values (95 and 114 mM−1 s−1, respectively), well within the region of interest for MRI techniques. |
| Databáze: | OpenAIRE |
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