Ultra-low gadolinium doping in multi-core iron oxide enables efficient dual-mode MRI and magnetic hyperthermia: a structure–function study
We present a novel strategy for engineering multifunctional nanoplatforms for cancer theranostics by employing ultra-low gadolinium (Gd<sup>3+</sup>) doping to optimize the performance of maghemite (γ-Fe<sub>2</sub>O<sub>3</sub>) "nanoflowers" for both magnetic resonance imaging (MRI) and magnetic hyperthermia treatment (MHT). Controlled Gd<sup>3+</sup> doping up to 1.7 mol% was sufficient to significantly alter the material properties while preserving the γ-Fe<sub>2</sub>O<sub>3</sub> phase and hierarchical multi-core architecture. X-ray photoelectron spectroscopy (XPS) revealed that doping induces critical surface defects, specifically a gradual increase in surface Fe<sup>2+</sup> species and non-lattice oxygen with increasing Gd<sup>3+</sup> content, indicating redox imbalance and the formation of oxygen vacancies. Electron paramagnetic resonance (EPR) measurements confirmed that these defects enhance magnetic anisotropy and spin disorder, while SQUID magnetometry showed that all samples retained superparamagnetic behavior despite a non-monotonic decrease in saturation magnetization. Under external alternating magnetic fields (AMF), the Gd<sub>0.011</sub>Fe<sub>1.989</sub>O<sub>3</sub> sample exhibited the highest MHT performance, with Intrinsic Loss Power (ILP) values reaching up to 2.73 nH m<sup>2</sup> kg<sup>-1</sup>. Simultaneously, MRI relaxometry at 7 T demonstrated that low-level Gd<sup>3+</sup> doping markedly improved both longitudinal (<i>r</i><sub>1</sub>) and transverse (<i>r</i><sub>2</sub>) relaxivities. The Gd<sub>0.022</sub>Fe<sub>1.978</sub>O<sub>3</sub> sample achieved an exceptional <i>r</i><sub>2</sub> value of 253.3 mM<sup>-1</sup> s<sup>-1</sup>, with an <i>r</i><sub>2</sub>/<i>r</i><sub>1</sub> ratio exceeding 220, making it a powerful <i>T</i><sub>2</sub>-weighted MRI contrast agent. Importantly, the Gd<sub>0.011</sub>Fe<sub>1.989</sub>O<sub>3</sub> sample showed a tunable balance, with a favorable <i>r</i><sub>2</sub>/<i>r</i><sub>1</sub> ratio suitable for dual-mode <i>T</i><sub>1</sub>/<i>T</i><sub>2</sub> MRI imaging and MHT. These findings underline the novelty of operating in an ultra-low Gd regime, where defect engineering and tailored multi-core architecture synergistically optimize the structure-property-function relationship, paving the way for safer and more effective theranostic nanoplatforms.
Authors
- Bratislav V. Antić (ORCID: https://orcid.org/0000-0002-5693-6401)
- Oliver Štrbák (ORCID: https://orcid.org/0000-0002-0212-3392)
- Ralitsa B. Mladenova (ORCID: https://orcid.org/0000-0002-9464-6026)
- Sanja Vranješ‐Đurić (ORCID: https://orcid.org/0000-0002-6340-2387)
- Vladimír Girman
- Martin Fábian (ORCID: https://orcid.org/0000-0002-8893-4195)
- Jana Vojtová (ORCID: https://orcid.org/0000-0002-0759-8696)
- Biljana Dojčinović (ORCID: https://orcid.org/0000-0003-1479-8060)
- Hristo Kolev (ORCID: https://orcid.org/0000-0002-4231-9306)
- Miloš Ognjanović (ORCID: https://orcid.org/0000-0003-2889-4416)
Institutions
- University of Pavol Jozef Šafárik (SK)
- Slovak Academy of Sciences (SK)
- Bulgarian Academy of Sciences (BG)
- University of Belgrade (RS)
- Institute of Materials Research of the Slovak Academy of Sciences (SK)
- Institute of Geotechnics of the Slovak Academy of Sciences (SK)
- Institute of Physics of the Slovak Academy of Sciences (SK)
- Comenius University Bratislava (SK)
Publication Details
- Journal
- Nanoscale
- Published
- 2025-01-01
- DOI
- https://doi.org/10.1039/d5nr03307a
- Citations
- 1
- Primary Topic
- Characterization and Applications of Magnetic Nanoparticles
- Type
- article
- Field-Weighted Citation Impact
- 0.67