Fig. 3.

(a)–(d) Fluorescence emission spectra of free BrCy106 (a), BrCy111 (b), BrCy112 (c), and ICG (d) in 1X PBS in response to photoexcitation wavelengths of $750\pm 2.5\mathrm{nm}$ (for BrCy dyes) and $780\pm 2.5\mathrm{nm}$ (for ICG). (e) Normalized spectrally integrated fluorescence ($\sigma$) over the 765 to 900 nm spectral band for free BrCy dyes (excited at 750 nm) and 700 to 900 nm spectral band for ICG (excited at 780 nm). (f) Relative fluorescence quantum yield ($\varphi$) for the three free BrCy dyes as compared with free ICG in 1X PBS.