State Key Laboratory of Bioelectronics, National Demonstration Center for Experimental Biomedical Engineering Education, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, People's Republic of China.
Nanotechnology. 2018 Mar 2;29(9):094001. doi: 10.1088/1361-6528/aaa44a.
Lanthanide-doped up-conversion nanoparticles (UCNPs) provide a remote temperature sensing approach to monitoring biological microenvironments. In this research, the UCNPs of NaYF:Yb, Er@NaYF:Yb, Nd with hexagonal (β)-phase were synthesized and applied in cell temperature sensing as well as imaging after surface modification with meso-2, 3-dimercaptosuccinic acid. In the core-shell UCNPs, Yb ions were introduced as energy transfer media between sensitizers of Nd and activators of Er to improve Eremission and prevent their quenching behavior due to multiple energy levels of Nd. Under the excitations of 808 nm and 980 nm lasers, the NaYF:Yb, Er@NaYF:Yb, Nd nanoparticles exhibited an efficient green band with two emission peaks at 525 nm and 545 nm, respectively, which originated from the transitions of H → I and S → I for Er ions. We demonstrate that an occurrence of good logarithmic linearity exists between the intensity ratio of these two emission peaks and the reciprocal of the inside or outside temperature of NIH-3T3 cells. A better thermal stability is proved through temperature-dependent spectra with a heating-cooling cycle. The obtained viability of NIH-3T3 cells is greater than 90% after incubations of about 12 and 24 (h), and they possess a lower cytotoxicity of UCNPs. This work provides a method for monitoring the cell temperature and its living state from multiple dimensions including temperature response, cell images and visual up-conversion fluorescent color.
镧系掺杂上转换纳米粒子（UCNPs）提供了一种远程温度传感方法，用于监测生物微环境。在这项研究中，我们合成了具有六方（β）相的 NaYF:Yb, Er@NaYF:Yb, Nd UCNPs，并在经过介体-2,3-二甲酸二巯基丁二酸表面修饰后，将其应用于细胞温度传感和成像。在核壳 UCNPs 中，Yb 离子被引入作为 Nd 的敏化剂和 Er 的激活剂之间的能量转移介质，以提高 Eremission 并防止由于 Nd 的多个能级而导致的猝灭行为。在 808nm 和 980nm 激光的激发下，NaYF:Yb, Er@NaYF:Yb, Nd 纳米粒子分别表现出一个高效的绿光带，在 525nm 和 545nm 处有两个发射峰，分别来源于 Er 离子的 H→I 和 S→I 跃迁。我们证明，这两个发射峰的强度比与 NIH-3T3 细胞内外温度的倒数之间存在良好的对数线性关系。通过具有加热-冷却循环的温度依赖光谱证明了更好的热稳定性。孵育约 12 和 24（h）后，NIH-3T3 细胞的存活率大于 90%，且 UCNPs 的细胞毒性较低。这项工作提供了一种从多个维度监测细胞温度及其生存状态的方法，包括温度响应、细胞图像和可视化上转换荧光颜色。
