Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67034 Strasbourg, France.
Labex CSC, Fondation IcFRC/Université de Strasbourg, 8 allée Gaspard Monge BP 70028, F-67083 Strasbourg Cedex, France.
Nanoscale. 2021 Sep 2;13(34):14552-14571. doi: 10.1039/d1nr03335b.
Iron oxide nanoparticles (IONPs) are well-known contrast agents for MRI for a wide range of sizes and shapes. Their use as theranostic agents requires a better understanding of their magnetic hyperthermia properties and also the design of a biocompatible coating ensuring their stealth and a good biodistribution to allow targeting of specific diseases. Here, biocompatible IONPs of two different shapes (spherical and octopod) were designed and tested and to evaluate their abilities as high-end theranostic agents. IONPs featured a dendron coating that was shown to provide anti-fouling properties and a small hydrodynamic size favoring an circulation of the dendronized IONPs. While dendronized nanospheres of about 22 nm size revealed good combined theranostic properties ( = 303 mM s, SAR = 395 W g), octopods with a mean size of 18 nm displayed unprecedented characteristics to simultaneously act as MRI contrast agents and magnetic hyperthermia agents ( = 405 mM s, SAR = 950 W g). The extensive structural and magnetic characterization of the two dendronized IONPs reveals clear shape, surface and defect effects explaining their high performance. The octopods seem to induce unusual surface effects evidenced by different characterization techniques while the nanospheres show high internal defects favoring Néel relaxation for magnetic hyperthermia. The study of octopods with different sizes showed that Néel relaxation dominates at sizes below 20 nm while the Brownian one occurs at higher sizes. experiments demonstrated that the magnetic heating capability of octopods occurs especially at low frequencies. The coupling of a small amount of glucose on dendronized octopods succeeded in internalizing them and showing an effect of MH on tumor growth. All measurements evidenced a particular signature of octopods, which is attributed to higher anisotropy, surface effects and/or magnetic field inhomogeneity induced by tips. This approach aiming at an analysis of the structure-property relationships is important to design efficient theranostic nanoparticles.
氧化铁纳米粒子（IONPs）是广泛应用于各种尺寸和形状的磁共振成像（MRI）的造影剂。将其作为治疗诊断一体化试剂使用，需要更好地了解其磁热疗性能，并设计出具有生物相容性的涂层，以确保其隐形性和良好的生物分布，从而靶向特定疾病。在这里，我们设计并测试了两种不同形状（球形和八足形）的生物相容 IONPs，以评估它们作为高端治疗诊断一体化试剂的能力。IONPs 具有树枝状涂层，该涂层被证明具有抗污染性能和较小的流体力学尺寸，有利于树枝状 IONPs 的循环。虽然尺寸约为 22nm 的树枝状纳米球表现出良好的联合治疗诊断性能（ = 303 mM s，SAR = 395 W g），但平均尺寸为 18nm 的八足形纳米粒子表现出了前所未有的特性，可同时作为 MRI 造影剂和磁热疗试剂（ = 405 mM s，SAR = 950 W g）。对两种树枝状 IONPs 的广泛结构和磁性表征揭示了其高性能的明显的形状、表面和缺陷效应。八足形纳米粒子似乎诱导了不同的表面效应，这可以通过不同的表征技术来证明，而纳米球则表现出有利于磁热疗的高内缺陷。对不同尺寸的八足形纳米粒子的研究表明，Néel 弛豫在尺寸小于 20nm 时占主导地位，而布朗运动在较大尺寸时发生。磁热实验证明了八足形纳米粒子的磁性加热能力尤其在低频时发生。在树枝状八足形纳米粒子上少量的葡萄糖耦合成功地使它们内化，并显示出对肿瘤生长的磁热效应。所有的测量结果都证明了八足形纳米粒子的一个特殊特征，这归因于其较高的各向异性、表面效应和/或由尖端引起的磁场不均匀性。这种旨在分析结构-性能关系的方法对于设计高效的治疗诊断一体化纳米粒子非常重要。
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