Methylene blue, isosulfan blue, indocyanine green
Vital dye / NO synthase inhibitor / metHb reducer
Inhibits guanylate cyclase + nitric oxide synthase → reverses NO-mediated vasodilation. At low dose, reduces methemoglobin (Fe³⁺) → hemoglobin (Fe²⁺) via NADPH-methemoglobin reductase pathway.
Triarylmethane lymphatic-mapping dye
Selectively absorbed into lymphatic capillaries after subdermal/peritumoral injection. Tracks to first-station lymph node → blue staining identifies the sentinel node for biopsy in breast, melanoma, and gynecologic cancers.
Tricarbocyanine near-infrared fluorescent dye
After IV or interstitial injection, ICG binds plasma proteins (mostly albumin) and fluoresces at 805–835 nm under near-infrared (NIR) imaging. Used for real-time vascular and lymphatic visualization, hepatic function testing, and tissue perfusion assessment.
Blue diagnostic dye (renally excreted)
Blue dye rapidly excreted by the kidneys → visualizes ureteral efflux/urine flow. Mild α-agonist activity → transient hypertension.
Fluorescent diagnostic dye (yellow-green)
Fluoresces under blue/UV light → visualizes vasculature + perfusion + epithelial defects. Not blue, but grouped with surgical/diagnostic dyes.