Characteristics and specificity of the interaction of a fluorochrome from aniline blue (sirofluor) with polysaccharides

The effects of polysaccharide structure and environment on the formation of fluorescent complexes between the polysaccharide and a fluorochrome (4,4′ - carbonylbis (benzene-4,1-diyl) bis(imino)] bisbenzenesulfonic acid (Sirofluor) isolated from the triarylmethane dye, aniline blue, have been studied. Amongst the wide range of water-soluble polysaccharides tested, fluorescent complexes are formed only with glucans, the strongest fluorescence being obtained with linear (1 → 3)-β-d-glucans and with linear (1 → 3)-β-d-glucans bearing single glucose residues attached at the 6-position. The fluorescence of complexes formed with water-insoluble polysaccharides depends on the ionic environment as well as the polysaccharide structure. (1 → 3)-β-d-Glucans form strongly fluorescent complexes in the dry state and in the presence of water or phosphate buffer. Various cellulose ((1 → 4)-β-d-glucan) samples form strongly fluorescent complexes in the dry state and in the presence of phosphate buffer, but are significantly reduced in the presence of water alone.