Ultra-Low Gadolinium Doping in Multi-Core Iron Oxide Enables Efficient Dual-Mode MRI and Magnetic Hyperthermia: A Structure-Function Study

IF 5.1 3区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nanoscale Pub Date : 2025-09-29 DOI:10.1039/d5nr03307a

Milos Ognjanovic, Ralitsa Mladenova, Jana Vojtova, Oliver Strbak, Hristo G. Kolev, Martin Fabian, Vladimir Girman, Biljana Dojcinovic, Sanja Vranješ Djurić, Bratislav Antic

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Abstract

We present a novel strategy for engineering multifunctional nanoplatforms for cancer theranostics by employing ultra-low gadolinium (Gd3+) doping to optimize the performance of maghemite (γ-Fe2O3) “nanoflowers” for both magnetic resonance imaging (MRI) and magnetic hyperthermia treatment (MHT). Controlled Gd3+ doping up to 1.7 mol% was sufficient to significantly alter the material properties while preserving the γ-Fe2O3 phase and hierarchical multi-core architecture. X-ray photoelectron spectroscopy (XPS) revealed that doping induces critical surface defects, specifically a gradual increase in surface Fe2+ species and non-lattice oxygen with increasing Gd3+ 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 Gd0.011Fe1.989O3 sample exhibited the highest MHT performance, with Intrinsic Loss Power (ILP) values reaching up to 2.73 nH·m2/kg. Simultaneously, MRI relaxometry at 7 T demonstrated that low-level Gd3+ doping markedly improved both longitudinal (r1) and transverse (r2) relaxivities. The Gd0.022Fe1.978O3 sample achieved an exceptional r2 value of 253.3 mM−1s−1, with an r2/r1 ratio exceeding 220, making it a powerful T2-weighted MRI contrast agent. Importantly, the Gd0.011Fe1.989O3 sample showed a tunable balance, with a favorable r2/r1 ratio suitable for dual-mode T1/T2 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.

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超低钆掺杂在多核氧化铁中实现高效的双模MRI和磁热疗：结构-功能研究

我们提出了一种用于癌症治疗的工程多功能纳米平台的新策略，通过超低钆（Gd3+）掺杂来优化磁赤铁矿（γ-Fe2O3）“纳米花”在磁共振成像（MRI）和磁热疗（MHT）中的性能。控制Gd3+掺入1.7 mol%足以显著改变材料性能，同时保留γ-Fe2O3相和分层多核结构。x射线光电子能谱（XPS）显示，掺杂诱导了临界表面缺陷，特别是随着Gd3+含量的增加，表面Fe2+种类和非晶格氧逐渐增加，表明氧化还原不平衡和氧空位的形成。电子顺磁共振（EPR）测量证实，这些缺陷增强了磁性各向异性和自旋无序性，而SQUID磁强计显示，尽管饱和磁化强度非单调降低，但所有样品都保持了超顺磁性行为。在外加交变磁场（AMF）下，Gd0.011Fe1.989O3样品表现出最高的MHT性能，其本质损耗功率（ILP）值高达2.73 nH·m2/kg。同时，7 T时的MRI弛豫测量显示，低水平Gd3+掺杂显著改善了纵向（r1）和横向（r2）弛豫度。Gd0.022Fe1.978O3样品的r2值为253.3 mM−1s−1，r2/r1比超过220，使其成为强大的t2加权MRI造影剂。重要的是，Gd0.011Fe1.989O3样品显示出可调谐的平衡，具有良好的r2/r1比，适用于双模T1/T2 MRI成像和MHT。这些发现强调了在超低Gd环境下工作的新颖性，其中缺陷工程和定制的多核架构协同优化了结构-性能-功能关系，为更安全，更有效的治疗纳米平台铺平了道路。

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来源期刊

Nanoscale CHEMISTRY, MULTIDISCIPLINARY-NANOSCIENCE & NANOTECHNOLOGY

CiteScore

12.10

自引率

3.00%

发文量

1628

审稿时长

1.6 months

期刊介绍： Nanoscale is a high-impact international journal, publishing high-quality research across nanoscience and nanotechnology. Nanoscale publishes a full mix of research articles on experimental and theoretical work, including reviews, communications, and full papers.Highly interdisciplinary, this journal appeals to scientists, researchers and professionals interested in nanoscience and nanotechnology, quantum materials and quantum technology, including the areas of physics, chemistry, biology, medicine, materials, energy/environment, information technology, detection science, healthcare and drug discovery, and electronics.