The study of the zinc biology requires molecular probes with proper zinc affinity. We developed a low-affinity zinc probe (HBO-ACR) based on an azacrown ether (ACR) and an 2-(2-hydroxyphenyl)benzoxazole (HBO) fluorophore. This probe design imposed positive charge in the vicinity of a zinc coordination center, which enabled fluorescence turn-on responses to high levels of zinc without being affected by the pH and the presence of other transition-metal ions. Steady-state and transient photophysical investigations suggested that such a high tolerance benefits from orchestrated actions of proton-induced nonradiative and zinc-induced radiative control. The zinc bioimaging utility of HBO-ACR has been fully demonstrated with the use of human pancreas epidermoid carcinoma, PANC-1 cells, and rodent hippocampal neurons from cultures and acute brain slices. The results obtained through our studies established the validity of incorporating positively charged ionophores for the creation of low-affinity probes for the visualization of biometals.
Bibliographical noteFunding Information:
This work was supported by the MSIP of Korea through the GFP (Grant CISS-2012M3A6A6054204 to S.B.J. and Y.Y.) and NRF (Grant 2012M2B2B1055502 to H.K. and 2014R1A1A1A05003770 to S.B.J.). The authors acknowledge Dr. Seung-Hae Kwon and So-Young Kim at Korea Basic Science Institute Chuncheon Center, for microscopic experiments.
© 2017 American Chemical Society.