NBD-TMA

  NBD-TMA ([2-(4-nitro-2,1,3-benzoxadiazol-7-yl)aminoethyl]trimethylammonium) is a small (139 u), positively charged (+1) fluorescent dye. It was also known as EAM-1 (N,N,N,-Trimethyl-2[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]ethanaminium iodide) when it was briefly supplied by Macrocyclics Company as an iodide complex.

Additional recommended knowledge

Recognize and detect the effects of electrostatic charges on your balance

Essential Laboratory Skills Guide

Don't let static charges disrupt your weighing accuracy

NBD-TMA has an excitation maximum at 458 nm and an emission maximum at 530 nm. It also has a smaller local excitation maximum around 343 nm. The molar extinction coefficient is about 13,000 cm^-1M^-1 and its overall effective fluorescence is about 1% that of fluorescein. It is only mildly sensitive to halide ion collision quenching.

NBD-TMA was designed as a probe for monitoring renal transport of organic cations. As a small, positively charged fluorophore, it has also seen use as a tracer for measuring gap junction coupling in cases of cation selective connexin channels.

Further reading

• PMID 10864014
• PMID 15869481