Trypan Blue (Direct Blue 14)

Technical Specifications

Product Description & Scientific Applications

Trypan Blue (Direct Blue 14) is a vital dye that does not cross intact plasma membranes: living cells exclude it, while cells with damaged membranes admit it and stain blue.

Common Scientific Applications

Dye-exclusion viability counting. Mixed with a cell suspension, Trypan Blue gives dead cells a blue cytoplasm while viable cells remain clear, scored by haemocytometer or automated cell counter to read the percentage of live cells. The stain reports membrane integrity, not death: pore formation admits the dye into cells that stay viable, and the dye can rupture dead cells so they disappear from the count and inflate the viability figure. Once bound to protein, Trypan Blue becomes fluorescent, allowing dead cells to be scored instead by flow cytometry.

Cytotoxicity endpoint. Trypan Blue uptake gives a direct, structural readout for dose-response testing of cytotoxic compounds and permeabilising treatments. It complements metabolic assays such as MTT, whose signal can fall through loss of enzyme activity without the cells having died.

Membrane-impermeable fluorescence quencher. Because it stays outside intact cells, Trypan Blue suppresses the fluorescence of labelled particles resting on the cell surface while internalised material keeps emitting. Added at the end of a phagocytosis assay, it lets flow cytometry or microscopy separate ingested bacteria, erythrocytes, or zymosan from particles that are only bound. The same quenching distinguishes internalised α-synuclein fibrils from extracellular seed in cultured neurons.

Ophthalmic surgical stain. Trypan Blue stains the anterior lens capsule, making the capsulorhexis visible during cataract surgery when no red fundus reflex is available, as in mature or white cataract. In vitreoretinal surgery it stains the internal limiting membrane, epiretinal membrane, and posterior hyaloid for controlled peeling. Staining also stiffens the anterior capsule, most markedly in diabetic eyes.

Vascular-permeability tracer. Injected with albumin into animal models, Trypan Blue is retained in vessels where the endothelium is intact and leaks into tissue where vascular permeability rises. The retained dye is extracted and measured spectrophotometrically to quantify endothelial leakage induced by mediators such as TNF.

Plant tissue staining. In infected leaves, Trypan Blue stains dead plant cells together with invading fungal or oomycete hyphae, so one preparation reports host cell death alongside pathogen spread; it has tracked Leptosphaeria maculans and Phytophthora infestans at infection sites. In roots, Trypan Blue is the standard stain for arbuscular mycorrhizal colonisation, which is scored by grid intersection.

Shipping Destinations

• EU & UK: Priority delivery, 2–5 business days.
• Norway (DDP): 3–7 business days, duties and taxes prepaid.
• Switzerland (DDP): 3–7 business days, duties and taxes prepaid.