Fig. 1.

Chlorine-containing albumin-seeking dyes covalently bind to albumin and increase brightness. (a) Schematic diagram of the covalent binding site of chlorine-containing cyanine dye and albumin. (b) Structural formula of IR-780, IR-808, IR-783, and ICG. (c) Brightness of four dyes (50 nM) in DMSO, PBS, and BSA with incubating at 60 ºC of 1:1 molar ratio (mean ± SEM, n = 3). (d) Mass spectrometric analysis of four dyes in BSA with 1:1 reaction molar ratio at 37 ºC for 2 h. (e-f) Gel electrophoretic analysis of fluorescence intensity of four dyes in BSA at 1:1 and 10:1 reaction molar ratio at 37 ºC for 2 h (mean ± SEM, n = 3)