Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241, People's Republic of China.
Biosens Bioelectron. 2017 Sep 15;95:21-26. doi: 10.1016/j.bios.2017.04.010. Epub 2017 Apr 12.
An efficient near-infrared fluorescence probe has been developed for the sequential detection of Cu, pyrophosphate (PO, PPi), and alkaline phosphatase (ALP), which is based on the "off-on-off" fluorescence switch of branched polyethyleneimine (PEI)-capped NaGdF:Yb/Tm upconversion nanoparticles (UCNPs). The fluorescence is quenched via energy transfer from UCNPs to Cu for the coordination of PEI with Cu. The strong affinity between Cu and PPi leads to the formation of Cu-PPi complex and results in the detachment of Cu from the surface of UCNPs, thus the fluorescence is triggered on. ALP-directed hydrolysis of PPi causes the disassembly of Cu-PPi complex and re-conjugation between Cu with PEI, which leads to the switch-off fluorescence of UCNPs. The system allows sequential analysis of Cu, PPi, and ALP by modulating the switch of the fluorescence of UCNPs with detection limits of 57.8nM, 184nM, and 0.019U/mL for Cu, PPi, and ALP, respectively. By virtue of the NIR feature and excellent biocompatibility, the UCNPs-based probes are suitable for bioimaging. Taking Cu visualization as a model, the nanoprobes have been successfully applied for intracellular imaging of Cu in living cells.
一种高效的近红外荧光探针已被开发出来，用于顺序检测 Cu、焦磷酸盐 (PO、PPi) 和碱性磷酸酶 (ALP)，该探针基于支化聚乙烯亚胺 (PEI) 封端的 NaGdF:Yb/Tm 上转换纳米粒子 (UCNPs) 的“关-开-关”荧光开关。通过 UCNPs 与 Cu 的能量转移，荧光被猝灭，因为 PEI 与 Cu 配位。Cu 与 PPi 之间的强亲和力导致 Cu-PPi 配合物的形成，并导致 Cu 从 UCNPs 表面脱离，从而触发荧光。ALP 定向水解 PPi 导致 Cu-PPi 配合物的解体和 Cu 与 PEI 之间的重新共轭，从而导致 UCNPs 的荧光关闭。该系统通过调节 UCNPs 的荧光开关，实现了对 Cu、PPi 和 ALP 的顺序分析，Cu、PPi 和 ALP 的检测限分别为 57.8nM、184nM 和 0.019U/mL。由于具有近红外特征和优异的生物相容性，基于 UCNPs 的探针适用于生物成像。以 Cu 可视化为例，该纳米探针已成功应用于活细胞内 Cu 的细胞内成像。
