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. Author manuscript; available in PMC: 2008 Dec 19.
Published in final edited form as: Front Biosci. 2007 Jan 1;12:2646–2657. doi: 10.2741/2261

Figure 4.

Figure 4

The bleaching rate (t½) of calcein fluorescence depends on the excitation wavelength (nm). Half times were calculated by fitting data to single exponential decay curves (see Materials and Methods) of intracellular calcein fluorescence bleaching due to continuous laser exposure using OPE 488nm (□) or a range of two-photon NIR wavelengths. TPE fluorescent images were acquired with internal (□) or non-de-scanned external detectors (△) with error bars indicating standard deviations (minimum of 7 cells). TPE wavelengths of 720 and 760nm showed small improvements in t½ compared with 488nm OPE; however, large increases in t½ were observed at TPE wavelengths of 800nm and above. The use of NDDs improved t½ at every TPE wavelength tested.