Synthesis of Ligand-Free Colloidally Stable Water Dispersible Brightly Luminescent Lanthanide-Doped Upconverting Nanoparticles
Synthesis of Ligand-Free Colloidally Stable Water Dispersible Brightly Luminescent Lanthanide-Doped Upconverting Nanoparticles
复制标题
DOI：
10.1021/nl1041929
复制
发表时间：
2011-02-01
期刊：
影响因子：
10.8
通讯作者：
Capobianco, John A.
中科院分区：
文献类型：
--
作者：
Bogdan, Nicoleta;Vetrone, Fiorenzo;Capobianco, John A.
金属三氟乙酸酯的热分解合成被广泛应用于制备油酸盐包覆的上转换稀土掺杂的NaYF4：Er3+/Yb3+纳米粒子(Ln-UCNPs)。这些纳米粒子不具有固有的水分散性，需要进行不方便的合成后处理才能使其成为水分散的。在这里，我们开发了一种新颖而简便的方法来获得水分散的、无配体的、明亮的上转换Ln-UCNPs。我们发现上转换发光受稀土离子在Ln-UCNPs表面的局域环境的影响。我们观察到分散在甲苯中的Ln-UCNPs与分散在水中的Ln-UCNPs的积分上转换红绿光发射比有很大的不同。我们可以通过pH和H/D同位素振动控制红光和绿光激发态的辐射和非辐射弛豫路径来增强或抑制上转换发光。无配体、水分散的Ln-UCNPs的直接生物功能化将为靶向和药物输送应用提供无数新的机会。
The synthesis using the thermal decomposition of metal trifluoroacetates is being widely used to prepare oleate-capped lanthanide-doped upconverting NaYF4:Er3+/Yb3+ nanoparticles (Ln-UCNPs). These nanoparticles have no inherent aqueous dispersibility and inconvenient postsynthesis treatments are required to render them water dispersible. Here, we have developed a novel and facile approach to obtain water-dispersible, ligand-free, brightly upconverting Ln-UCNPs. We show that the upconversion luminescence is affected by the local environment of the lanthanide ions at the surface of the Ln-UCNPs We observe a dramatic difference of the integrated upconverted red green emission ratio for Ln-UCNPs dispersed in toluene compared to Ln-UCNPs dispersed in water. We can enhance or deactivate the upconversion luminescence by pH and H/D isotope vibronic control over the competitive radiative and nonradiative relaxation pathways for the red and green excited states. Direct biofunctionalization of the ligand-free, water dispersible Ln-UCNPs will enable myriad new opportunities in targeting and drug delivery applications.