We demonstrate enhanced sensitivity in two-photon flow cytometry with an extended cavity laser excitation source. At low power, the home-built 20-MHz oscillator was able to detect a significantly larger fraction, in either phosphate buffered saline (PBS) or whole blood, of green fluorescent protein (GFP)–expressing MCA-207 cells cross-labeled with the membrane-binding lipophilic dye DiD. A geometrical model is used to explain unique features of the signals resulting from the different spatial distribution of DiD and GFP. These unique features include sub-square law scaling of unsaturated two-photon signal, a sigmoidal sensitivity curve for detection under varying powers for cell detection thresholds as low as a single photon, and uncorrelated signal strengths in two detection channels.
CITATION STYLE
Tkaczyk, E. R., Tkaczyk, A. H., Katnik, S., Ye, J. Y., Luker, K. E., Luker, G. D., … Norris, T. B. (2008). Extended cavity laser enhanced two-photon flow cytometry. Journal of Biomedical Optics, 13(4), 041319. https://doi.org/10.1117/1.2967983
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