Coating Effects on MR Relaxivities: Dendron-Iron Oxide Nanoparticle Models

描述（由申请人提供）：揭示氧化铁纳米团簇的表面结构和磁共振弛豫率之间的关系是提高这类造影剂的造影特异性和扩大其适用性的关键。氧化铁纳米颗粒的表面性质对决定颗粒弛豫性质的整体磁特性具有巨大影响。由于不完全的配位球，铁氧化物表面的对称性由于磁性金属阳离子的化学环境而降低，并且纳米颗粒表面的性质通常不同于主体纳米颗粒内的性质。随着纳米颗粒尺寸的减小，由于颗粒内表面原子的比例增加，表面相互作用对纳米颗粒磁性的影响变得更加显著。此外，涂层性质可以调节水分子的表面进入、颗粒流体动力学尺寸、翻滚速率、溶解度、微尺度聚集、组织摄取和/或细胞内分配。然而，由于缺乏一个模型系统，具有有力的控制其表面核心特性，详细调查的结构参数表面和铁氧化物纳米粒子的弛豫率之间的关系仍然是有限的。我们相信，树枝状保护的氧化铁纳米粒子可以发展成为一个新的模型，系统的表面效应对MR弛豫性能。树枝化基元的合成将以受控的、限定的和离散的方式实现常规的多步有机合成。树枝状-氧化铁纳米颗粒的壳层结构可以精确地构造和调节。此外，由于其树枝状结构涂层，树枝状结构-氧化铁纳米颗粒是一类独特的造影剂，与传统的造影剂相比具有许多潜在的优势。例如，当静脉内注射时，基于树枝状分子的血流泄漏到其他身体隔室中可以通过改变树枝状分子的分子量、覆盖率和功能性来潜在地调节。我们的AREA（R15）资助申请设立了两个具体目标：（1）开发构建具有各种表面静电和其他特性的树枝状涂层氧化铁纳米颗粒的新途径;（2）检查NMR弛豫诱导特性树枝状氧化铁纳米颗粒在体和细胞环境中，特别是关于效果。我们相信，这一中等规模的R15赠款将是一个高价值的投资，为一个重要的领域，还没有得到太多的关注，从MR社区。

DESCRIPTION (provided by applicant): Uncovering the relationship between the surface structure and magnetic resonance relaxivities of iron oxide nanoclusters is key to improving the contrast specificity and expanding applicability of this class of contrast agents. The surface properties of iron oxide nanoparticles have enormous effects on the overall magnetic characteristics that determine the particles' relaxation properties. The symmetry at the iron oxide surface is reduced for the chemical surroundings of magnetic metal cations due to the incomplete coordination sphere, and properties of the nanoparticle surfaces are usually different from those within the body nanoparticle. As the size of nanoparticles decreases, the influence of surface interactions magnetic properties of the nanoparticles becomes more significant due to the increased fraction of surface atoms within the particle. Additionally, the coating properties can modulate surface access of water molecules, the particle hydrodynamic size, tumbling rate, solubility, microscale clustering, tissue uptake, and/or intracellular partitioning. However, due to the lack of a model system that has vigorous controls of both its surface core characteristics, detailed investigations of the relationships between structural parameters surface and the relaxivities of iron oxide nanoparticles are still limited. We believe that dendron protected iron oxide nanoparticles can be developed into a novel model for systematically the surface effects on MR relaxation properties. The synthesis of dendrons will be achieved conventional multiple-step organic syntheses in a controlled, defined, and discrete manner. structure of the shell coatings of dendron-iron oxide nanoparticles can be precisely constructed regulated. In addition, due to their dendron coatings, dendron-iron oxide nanoparticles unique class of contrast agents offering many potential advantages over conventional counterparts. For example, when injected intravenously, the leakage of dendron-based the bloodstream into other bodily compartments can potentially be tuned by varying the molecular weight, coverage, and functionality of the dendrons. Our AREA (R15) grant application has set up two specific aims: (1) developing new routes for constructing dendron-coated iron oxide nanoparticles that have various surface electrostatics and other properties; and (2) examining the NMR relaxation-inducing properties dendron-iron oxide nanoparticles in bulk and cellular environments, particularly regarding effects. We believe that this medium-sized R15 grant would be a high-value investment for an important area that has not received much attention from the MR community.