Carboxylic acid; also available as NHS-Ester, maleimide and coupled to biotin. High thermal and photostability, only little triplet formation. Dye is moderately hydrophilic. NHS-ester and maleimide show excellent solubility in polar solvents like DMF, DMSO or acetonitrile. Very stable under physiological pH-values and in buffers up to pH 8.5; degrades at higher pH.