Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Center for Biological and Environmental Nanotechnology, Rice University, Houston, Texas 77251-1892, USA.
Nat Nanotechnol. 2010 Nov;5(11):815-21. doi: 10.1038/nnano.2010.203. Epub 2010 Oct 24.
Magnetic resonance imaging contrast agents are currently designed by modifying their structural and physiochemical properties to improve relaxivity and to enhance image contrast. Here, we show a general method for increasing relaxivity by confining contrast agents inside the nanoporous structure of silicon particles. Magnevist, gadofullerenes and gadonanotubes were loaded inside the pores of quasi-hemispherical and discoidal particles. For all combinations of nanoconstructs, a boost in longitudinal proton relaxivity r(1) was observed: Magnevist, r(1) ≈ 14 mM(-1) s(-1)/Gd(3+) ion (∼ 8.15 × 10(+7) mM(-1) s(-1)/construct); gadofullerenes, r(1) ≈ 200 mM(-1) s(-1)/Gd(3+) ion (∼ 7 × 10(+9) mM(-1) s(-1)/construct); gadonanotubes, r(1) ≈ 150 mM(-1) s(-1)/Gd(3+) ion (∼ 2 × 10(+9) mM(-1) s(-1)/construct). These relaxivity values are about 4 to 50 times larger than those of clinically available gadolinium-based agents (∼ 4 mM(-1) s(-1)/Gd(3+) ion). The enhancement in contrast is attributed to the geometrical confinement of the agents, which influences the paramagnetic behaviour of the Gd(3+) ions. Thus, nanoscale confinement offers a new and general strategy for enhancing the contrast of gadolinium-based contrast agents.
磁共振成像对比剂目前通过修饰其结构和物理化学性质来设计，以提高弛豫率并增强图像对比度。在这里，我们展示了一种通过将对比剂限制在硅颗粒的纳米多孔结构内来提高弛豫率的通用方法。Magnevist、钆富勒烯和钆纳米管被装载在准半球形和圆盘形颗粒的孔内。对于所有纳米结构的组合，观察到纵向质子弛豫率 r(1)的提高：Magnevist，r(1)≈14 mM(-1) s(-1)/Gd(3+)离子（约 8.15×10(+7) mM(-1) s(-1)/构建物）；钆富勒烯，r(1)≈200 mM(-1) s(-1)/Gd(3+)离子（约 7×10(+9) mM(-1) s(-1)/构建物）；钆纳米管，r(1)≈150 mM(-1) s(-1)/Gd(3+)离子（约 2×10(+9) mM(-1) s(-1)/构建物）。这些弛豫率值比临床可用的基于钆的造影剂（约 4 mM(-1) s(-1)/Gd(3+)离子）大 4 到 50 倍。对比度的增强归因于造影剂的几何限制，这影响了 Gd(3+)离子的顺磁行为。因此，纳米尺度的限制为增强基于钆的造影剂的对比度提供了一种新的通用策略。
