Send to

Choose Destination
J Am Chem Soc. 2004 Mar 10;126(9):2799-806.

Optical sensor for the detection of caspase-9 activity in a single cell.

Author information

Advanced Biomedical Science and Technology Group, Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6101, USA.


We demonstrate for the first time, the application and utility of a unique optical sensor having a nanoprobe for monitoring the onset of the mitochondrial pathway of apoptosis in a single living cell by detecting enzymatic activities of caspase-9. Minimally invasive analysis of single live MCF-7 cells for caspase-9 activity is demonstrated using the optical sensor which employs a modification of an immunochemical assay format for the immobilization of nonfluorescent enzyme substrate, Leucine-GlutamicAcid-Histidine-AsparticAcid-7-amino-4-methylcoumarin (LEHD-AMC). LEHD-AMC covalently attached on the nanoprobe tip of an optical sensor is cleaved during apoptosis by caspase-9 generating free AMC. An evanescent field is used to excite cleaved AMC and the resulting fluorescence signal is detected. By quantitatively monitoring the changes in fluorescence signals, caspase-9 activity within a single living MCF-7 cell was detected. By comparing of the fluorescence signals from apoptotic cells induced by photodynamic treatment and nonapoptotic cells, we successfully detected caspase-9 activity, which indicates the onset of apoptosis in the cells.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for American Chemical Society
Loading ...
Support Center