(A) Chemical structures of TOCL, TTAPE-Me and NAO. (B) Emission spectra and (C) the corresponding fluorescence photographs of TTAPE-Me solutions in the absence and presence of vesicles, with and without CL. CL-containing and CL-free vesicles are composed of TOCL/DOPC (1:1 molar ratio, CL-containing) and pure DOPC (CL-free), respectively, in a 25 mM HEPES buffer at pH 7.4. [dye] = 10 μM; [lipid]total = 22 μM; λex = 350 nm.