Single-step synthesis of Er3+ and Yb3+ ions doped molybdate/Gd2O3 core–shell nanoparticles for biomedical imaging
Single-step synthesis of Er3+ and Yb3+ ions doped molybdate/Gd2O3 core–shell nanoparticles for biomedical imaging
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DOI：
10.1088/1361-6528/aa9974
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发表时间：
2018-01
期刊：
影响因子：
3.5
通讯作者：
I. Kamińska;D. Elbaum;B. Sikora;P. Kowalik;J. Mikulski;Zofia Felcyn;P. Samól;T. Wojciechowski
中科院分区：
文献类型：
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作者：
I. Kamińska;D. Elbaum;B. Sikora;P. Kowalik;J. Mikulski;Zofia Felcyn;P. Samól;T. Wojciechowski
纳米结构作为颜色可调的发光标记已经成为生物成像和生物传感的主要工具。本文采用一步均匀沉淀法制备了钼酸根/Gd_2O_3混合稀土离子(Er，Er~(3+)和Yb，Yb~(3+))核壳纳米粒子。用阴极发光和光致发光研究了其发光性质。用扫描电子显微镜和透射电子显微镜观察和确定纳米粒子的大小和形状。得到了球形纳米粒子。用X-射线衍射仪和能谱仪对其核壳结构进行了表征。我们推测富钼酸盐核的形成是由于析出过程中钼离子的高分凝系数所致。焙烧过程导致了δ/ξ(核/壳)Np掺杂的Er和Yb离子的结晶，其中δ-Gd-钼酸盐和ξ-Mo酸盐或Gd-氧化物。我们证实了两种不同的上转换机制。在钼离子存在下，在纳米粒子的核心形成了Yb3+-MoO42−(|2F7/2，3T2>)二聚体。由于二聚体吸收了两个980 nm的光子，我们在上转换过程中观察到了增强的绿色发光。然而，对于Gd2O3：Er，Yb纳米粒子(不含Mo离子)形成的壳层，发生了典型的能量转移上转换，导致了红色发光。我们证明，NPs通过内吞作用进入HeLa和星形胶质细胞的胞浆。核壳NPs是对受试电池内部(发光衰减较短)和外部(发光衰减较长)环境的敏感传感器。用四甲基偶氮唑盐比色法检测纳米粒的毒性。
Nanostructures as color-tunable luminescent markers have become major, promising tools for bioimaging and biosensing. In this paper separated molybdate/Gd2O3 doped rare earth ions (erbium, Er3+ and ytterbium, Yb3+) core–shell nanoparticles (NPs), were fabricated by a one-step homogeneous precipitation process. Emission properties were studied by cathodo- and photoluminescence. Scanning electron and transmission electron microscopes were used to visualize and determine the size and shape of the NPs. Spherical NPs were obtained. Their core–shell structures were confirmed by x-ray diffraction and energy-dispersive x-ray spectroscopy measurements. We postulated that the molybdate rich core is formed due to high segregation coefficient of the Mo ion during the precipitation. The calcination process resulted in crystallization of δ/ξ (core/shell) NP doped Er and Yb ions, where δ—gadolinium molybdates and ξ—molybdates or gadolinium oxide. We confirmed two different upconversion mechanisms. In the presence of molybdenum ions, in the core of the NPs, Yb3+– MoO 4 2 − (∣2F7/2, 3T2〉) dimers were formed. As a result of a two 980 nm photon absorption by the dimer, we observed enhanced green luminescence in the upconversion process. However, for the shell formed by the Gd2O3:Er, Yb NPs (without the Mo ions), the typical energy transfer upconversion takes place, which results in red luminescence. We demonstrated that the NPs were transported into cytosol of the HeLa and astrocytes cells by endocytosis. The core–shell NPs are sensitive sensors for the environment prevailing inside (shorter luminescence decay) and outside (longer luminescence decay) of the tested cells. The toxicity of the NPs was examined using MTT assay.