indocyanine green + cysteine

Indocyanine green + cysteine is a combination of the fluorophore dye indocyanine green (ICG) and the amino acid cysteine. Indocyanine green is a water-soluble, near-infrared fluorescent dye used clinically in diagnostic imaging for assessments such as cardiac output, hepatic function, blood flow, and ophthalmic angiography. Cysteine as an additive can modify the optical and pharmacokinetic properties of ICG, likely by increasing aqueous solubility, influencing fluorescence intensity, and potentially altering plasma protein binding profiles. While ICG alone is well characterized, combinations with cysteine are often investigated in research as novel imaging agents or to enhance tumor-targeting for fluorescence-guided surgery or diagnostics. Specific mechanisms for this combination are not FDA-approved but may relate to altered fluorescent behavior, pharmacokinetics, or targeting using the free thiol group of cysteine (and potential tumor-environment interactions), but clinical application is not established.