Evans Blue (dye)

Evans Blue is a synthetic dye that is a diazo compound of sodium and sulfur, known for its vivid blue color. It is primarily used in biomedical research for the quantification of extravascular albumin and the measurement of blood volume. Evans Blue binds tightly to albumin, a protein in the blood, making it useful for tracking blood volume and studying the permeability of blood vessels.

History

Evans Blue was first synthesized in the early 20th century and has since been utilized in various scientific and medical research contexts. Its ability to bind to albumin and its bright blue color have made it a valuable tool for researchers studying the circulatory system and the properties of blood vessels.

Chemical Properties

Evans Blue is known chemically as T-1824 or Direct Blue 53. It has a high affinity for albumin, which allows it to be used as a marker in blood volume studies. The dye has a molecular weight of approximately 960.81 g/mol and a formula of C34H24N6Na4O14S4. It is soluble in water, making it easy to administer in biological experiments.

Applications in Research

Evans Blue dye is widely used in research to study the blood-brain barrier (BBB), vascular permeability, and blood volume. It is particularly useful in experiments that require the visualization of blood vessels or the measurement of substances that have leaked from the blood vessels into tissues.

Blood-Brain Barrier Studies

In studies of the BBB, Evans Blue can indicate areas where the barrier is compromised. When injected into the bloodstream, the dye should not cross a healthy BBB. However, in areas where the BBB is damaged, Evans Blue can leak into the brain tissue, marking the areas of damage.

Vascular Permeability

Evans Blue is also used to assess the permeability of blood vessels. By measuring the amount of dye that escapes from the vasculature into the surrounding tissue, researchers can quantify the permeability of blood vessels. This application is particularly important in studies of inflammation, where increased vascular permeability is a key feature.

Safety and Toxicity

While Evans Blue is useful for research purposes, it is important to note that it can be toxic in high concentrations or with prolonged exposure. Safety protocols must be followed when handling the dye to prevent adverse effects.

Conclusion

Evans Blue dye remains an important tool in biomedical research, offering valuable insights into the functioning of the blood-brain barrier, vascular permeability, and blood volume. Its ability to bind to albumin and its vivid coloration make it an indispensable dye for various research applications.

Evans Blue (dye) Resources
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