AAT Bioquest

Can indocyanine green (ICG) be conjugated to antibodies?

Posted August 13, 2021


Yes, indocyanine green (ICG) can be conjugated to antibodies. Studies have shown that ICG as an antibody-conjugate can be an effective photosensitizing agent. 1.8 ICG molecules per antibody produced the best results. When conjugated to antibodies, the ICG absorption peaks vary proportionally with concentration.

Conventional activated ICG dye, ICG-Sulfo-OSu, has been used for preparing ICG-antibody conjugates utilized in in vivo imaging research as antibody conjugates. However, the ICG hydrophobicity often causes some unspecific bindings. The PEG-modified ICG dyes are used to increase the hydrophobicity of the ICG dyes. The PEGylated ICGs shows better water solubility and significantly reducing unspecific binding.

Additional resources

Activatable fluorescent cys-diabody conjugated with indocyanine green derivative: consideration of fluorescent catabolite kinetics on molecular imaging


Indocyanine Green