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. Author manuscript; available in PMC: 2013 Sep 12.
Published in final edited form as: J Am Chem Soc. 2012 Aug 27;134(36):14789–14799. doi: 10.1021/ja3034137

Figure 4.

Figure 4

Properties of PSmOrange2 using a two-photon excitation (2PE). (A) Far-red fluorescence intensity of PSmOrange2 and PSmOrange achieved by 2P photoswitching using 40 mW of 900 nm light scanning at 1 frame per second for 5 min. (B) Far-red fluorescence intensity achieved at indicated wavelengths by 2P photoswitching using 90 mW of 900 nm light scanning at 1 frame per second for 30 s. (C) Far-red fluorescence intensity after 2P photoswitching with the indicated laser powers at 900 nm and scanning at 1 frame per second. (D) Relative 2PE spectra (σ2PE) of orange and photoswitched far-red PSmOrange2 forms. (E) 2P image s of MTLn3 live cells expressing PSmOrange2 before (Pre) and after (Post) photoswitching using 90 mW of 2PE at 900 nm for 40 s. 1,200 nm 2PE and a 697/75 nm emission filter were used to generate and collect the fluorescence signal. Scale bar, 50 μm. (F) Mean far-red fluorescence intensities of PSmOrange2 expressing cells shown in (E). Error bars, SD.