Journal
BIOSENSORS & BIOELECTRONICS
Volume 95, Issue -, Pages 21-26Publisher
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2017.04.010
Keywords
Upconversion nanoparticles; Fluorescent probe; Copper ions; Pyrophosphate ions; Alkaline phosphatase; Bioimaging
Categories
Funding
- National Natural Science Foundation of China [21605050]
- Shanghai Natural Science Foundation [15ZR1411600]
- Postdoctoral Science Foundation of China [2015M570349]
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An efficient near-infrared fluorescence probe has been developed for the sequential detection of Cu2+, pyrophosphate (P2O74-, PPi), and alkaline phosphatase (ALP), which is based on the off-on-off fluorescence switch of branched polyethyleneimine (PEI)-capped NaGdF4:Yb/Tm upconversion nanoparticles (UCNPs). The fluorescence is quenched via energy transfer from UCNPs to Cu2+ for the coordination of PEI with Cu2+. The strong affinity between Cu2+ and PPi leads to the formation of Cu2+-PPi complex and results in the detachment of Cu2+ from the surface of UCNPs, thus the fluorescence is triggered on. ALP-directed hydrolysis of PPi causes the disassembly of Cu2+-PPi complex and re -conjugation between Cu2+ with PEI, which leads to the switch-off fluorescence of UCNPs. The system allows sequential analysis of Cu2+, PPi, and ALP by modulating the switch of the fluorescence of UCNPs with detection limits of 57.8 nM, 184 nM, and 0.019 U/mL for Cu2+, PPi, and ALP, respectively. By virtue of the MR feature and excellent biocompatibility, the UCNPs-based probes are suitable for bioimaging. Taking Cu2+ visualization as a model, the nanoprobes have been successfully applied for intracellular imaging of Cu2+ in living cells.
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