uncaging luciferin by photolysis might work as an efficient
bioluminescent probe for tracking the dynamics of the
luciferase expression in living animals.
In conclusion, this work presents the design and evaluation
of new photoactivable bioluminescent substrates for imaging
the luciferase activity in buffers, cells and living animals.
These stable, less toxic and cell permeable ‘‘caged’’ luciferin
derivatives display rapid photorelease of D-luciferin and confer
robust fluorescent and bioluminescent signals with minimum
background after brief UV irradiation. We expect that these
novel ‘‘caged’’ firefly luciferase substrates will offer new
opportunities for real-time monitoring the dynamics of the
cellular functions in vitro and in vivo.
Fig. 3 Fluorescence imaging of C6 glioma cells loaded with (A), (D);
D-luciferin only (25 mM); (B), (E); NPE-luciferin (3c) only (25 mM) but
no UV excitation; (C), (F); NPE-luciferin (3c) (25 mM) and followed
by 1 min UV excitation. Excitation filter: 460/40 nm; emission
filter: 535/50 nm.
The authors gratefully acknowledge URC (RG56/06),
A*Star BMRC (07/1/22/19/534) and SEP (RG139/06) grants
in Nanyang Technological University, Singapore. NCI Small
Animal Imaging Resource Program (SAIRP) grant R24
CA93862, and NCI in vivo Cellular Molecular Imaging Center
(ICMIC) grant P50 CA114747, USA. We also thank Prof.
Ken-Shiung Chen, in the School of Biological Sciences, NTU,
for his luminometer facility.
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Fig. 4 Imaging of fLuc activity in living mice (n = 4). The tumors
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ꢀc
This journal is The Royal Society of Chemistry 2009
4030 | Chem. Commun., 2009, 4028–4030