Harada Tomoaki, Yoshimura Hideyuki
Department of Physics, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, 214-8571, Japan.
Phys Chem Chem Phys. 2014 Jul 28;16(28):14947-52. doi: 10.1039/c4cp02131b.
Luminescent europium (Eu) and dysprosium (Dy) doped yttrium-vanadate (Y-V) nanoparticles (NPs) were synthesized in the cavity of the protein, apoferritin. Y-V NPs were synthesized by incubating a solution of apoferritin with Y(3+) and VO3(-) ions in the presence of ethylene diamine-N-N'-diacetic acid (EDDA). EDDA plays an important role in preventing Y-vanadate precipitation in bulk solution by chelating the Y(3+) ions. Using high resolution electron microscopy, the obtained NPs in the apoferritin cavities were confirmed to be amorphous, and to consist of Y and V. Eu-doped Y-V (Y-V:Eu) NPs were synthesized by the same procedure as Y-V NPs, except that Eu(NO3)3 was added. Y-V:Eu NPs exhibited a strong absorption peak due to the O-V charge transfer transition and remarkable luminescence at 618 nm due to the (5)D0 → (7)F2 transition. The luminescence lifetime of Y:Eu and Y-V:Eu NPs measured in H2O and D2O solution showed reduction of non-radiative transition to the O-H vibration in Y-V:Eu NPs. Accordingly, Y-V NPs showed strong luminescence compared to Y:Eu NPs. Dy-doped Y-V NPs were also synthesized in apoferritin cavities and showed luminescence peaks at 482 nm and 572 nm, corresponding to (4)F9/2 → (6)H15/2 and (4)F9/2 → (6)H13/2 transitions. These NPs stably dispersed in water solution since their aggregation was prevented by the protein shell. NPs encapsulated in the protein are likely to be biocompatible and would have significant potential for biological imaging applications.
在脱铁铁蛋白这种蛋白质的空腔内合成了发光的铕（Eu）和镝（Dy）掺杂的钒酸钇（Y-V）纳米颗粒（NPs）。通过在乙二胺-N-N'-二乙酸（EDDA）存在的情况下，将脱铁铁蛋白溶液与Y(3+)和VO3(-)离子孵育来合成Y-V NPs。EDDA通过螯合Y(3+)离子，在防止钒酸钇在本体溶液中沉淀方面发挥着重要作用。使用高分辨率电子显微镜，确认在脱铁铁蛋白空腔中获得的NPs是无定形的，且由Y和V组成。通过与合成Y-V NPs相同的程序合成了Eu掺杂的Y-V（Y-V:Eu）NPs，只是添加了Eu(NO3)3。Y-V:Eu NPs由于O-V电荷转移跃迁而表现出一个强吸收峰，并且由于(5)D0 → (7)F2跃迁在618 nm处有显著的发光。在H2O和D2O溶液中测量的Y:Eu和Y-V:Eu NPs的发光寿命表明，Y-V:Eu NPs中向O-H振动的非辐射跃迁减少。因此，与Y:Eu NPs相比，Y-V NPs表现出较强的发光。Dy掺杂的Y-V NPs也在脱铁铁蛋白空腔中合成，并在482 nm和572 nm处表现出发光峰，分别对应于(4)F9/2 → (6)H15/2和(4)F9/2 → (6)H13/2跃迁。这些NPs稳定地分散在水溶液中，因为它们的聚集被蛋白质外壳所阻止。包裹在蛋白质中的NPs可能具有生物相容性，并且在生物成像应用中具有巨大潜力。
