Table 1.

The optical properties of ICG from Sigma-Aldrich, bis-carboxylic acid ICG, ethanolamine-2-nitroimidazole-ICG, and piperazine-2-nitroimidazole-ICG.

Compound	${\lambda }_{\mathrm{abs}}^{\max }$ (nm)	${\lambda }_{\mathrm{ems}}^{\max }$ (nm)	Extinction coefficient $\epsilon$ (${\mathrm{M}}^{-1}{\mathrm{cm}}^{-1}$)	Quantum yield ($\mathrm{\Phi }$)
ICG from Sigma-Aldrich	780	807	115000	0.012
bis-carboxylic acid ICG	755	790	220920	0.0728
ethanolamine-2-nitroimidazole-ICG	760	790	159141	0.0420
piperazine-2-nitroimidazole-ICG	760	790	229543	0.0825

Note: ${\lambda }_{\mathrm{abs}}^{\max }$ is the wavelength measured at the maximum absorption spectrum, and ${\lambda }_{\mathrm{ems}}^{\max }$ is the wavelength measured at the maximum emission spectrum.