Abualrejal Murad M A, Eid Kamel, Abdullah Aboubakr M, Numan Abdulqawi Ahmed, Chen Hongda, Zhang Hua, Wang Zhenxin
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, People's Republic of China.
University of Science and Technology of China, Road Baohe District, Hefei, 230026, Anhui, People's Republic of China.
Mikrochim Acta. 2020 Aug 28;187(9):527. doi: 10.1007/s00604-020-04521-2.
A facile scalable approach is presented for the rational design of multidimensional, multilayered sand-clock-like UCNPs (denoted as UCCKs) bounded with high index facets, with a tunable Nd content, and without a template or multiple complicated reaction steps. This was achieved using the seed-mediated growth and subsequent longitudinal direction epitaxial growth with the assistance of oleic acid and NHF. The as-formed UCCKs composed of an inner layer (NaYF:Yb,Er,Ca), an intermediate layer (NaYF:Yb,Ca), and an outer layer (NaNdF:Yb,Ca). The outer shell, enriched with Nd sensitizer, augmented the near-infrared (NIR) photon absorption, whereas the intermediate shell, enriched with Yb, acted as a bridge for energy transfer from Nd to Er emitter in the inner core alongside with precluding any deleterious energy back-transfer from Er or quenching effect from Nd. These unique structural and compositional properties of UCCKs endowed the UCL intensity of UCCKs by 22 and 10 times higher than that of hexagonal UCNP core (NaYF:Yb,Er,Ca) and hexagonal UCNP core-shell (NaYF:Yb,Er,Ca@NaYF:Yb,Ca), respectively. Intriguingly, the UCL intensity increased significantly with increasing the content of Nd in the outer shell. The silica-coated UCCKs were used as excellent long-term luminescence probes for the in vitro bioimaging without any noteworthy cytotoxicity. The presented approach may pave the road for controlling the synthesis of multidimensional UCCKs for various applications. Graphical abstract We developed novel multidimensional multilayered sand-clock-like upconversion nanostructures composed of a spherical inner core (NaYF:Yb,Er,Ca), hexagonal intermediate shell (NaYF:Yb,Ca) and two up-down outer shell (NaNdF:Yb,Ca) with controllable Nd as an efficient and safe probe for bioimaging applications without any quenching effect.
本文提出了一种简便的可扩展方法，用于合理设计具有高折射率晶面、钕含量可调且无需模板或多个复杂反应步骤的多维、多层沙漏状上转换纳米粒子（记为UCCK）。这是通过种子介导生长以及随后在油酸和NHF的辅助下进行纵向外延生长来实现的。所形成的UCCK由内层（NaYF:Yb,Er,Ca）、中间层（NaYF:Yb,Ca）和外层（NaNdF:Yb,Ca）组成。富含钕敏化剂的外壳增强了近红外（NIR）光子吸收，而富含镱的中间壳层则作为能量从钕传递到内核中铒发射体的桥梁，同时防止任何有害的能量从铒反向传递或钕的猝灭效应。UCCK的这些独特结构和组成特性使UCCK的上转换发光强度分别比六方上转换纳米粒子核（NaYF:Yb,Er,Ca）和六方上转换纳米粒子核壳（NaYF:Yb,Er,Ca@NaYF:Yb,Ca）高22倍和10倍。有趣的是，上转换发光强度随着外壳中钕含量的增加而显著增加。二氧化硅包覆的UCCK用作体外生物成像的优异长期发光探针，且无任何明显的细胞毒性。所提出的方法可能为控制多维UCCK的合成以用于各种应用铺平道路。图形摘要我们开发了由球形内核（NaYF:Yb,Er,Ca）、六方中间壳层（NaYF:Yb,Ca）和两个上下外层（NaNdF:Yb,Ca）组成的新型多维多层沙漏状上转换纳米结构，其中钕含量可控，作为一种高效且安全的生物成像应用探针，无任何猝灭效应。
