The optical anisotropies (linear dichroism or LD and birefringence) of crystalline aggre-gates of the sulfonic azo-dye Ponceau SS and of dye complexed with chicken tendon collagen fiberswere investigated in order to assess their polarizing properties and similarity to liquid crystals. Insome...

The optical anisotropies (linear dichroism or LD and birefringence) of crystalline aggre-gates of the sulfonic azo-dye Ponceau SS and of dye complexed with chicken tendon collagen fiberswere investigated in order to assess their polarizing properties and similarity to liquid crystals. Insome experiments, the staining was preceded by treatment with picric acid. Crystalline fibrous aggre-gates of the dye had a negative LD, and their electronic transitions were oriented perpendicular tothe filamentary structures. The binding of Ponceau SS molecules to the collagen fibers altered the LDsignal, with variations in the fiber orientation affecting the resulting dichroic ratios. The long axis ofthe rod-like dye molecule was assumed to be bound in register, parallel to the collagen fiber. Picricacid did not affect the oriented binding of the azo dye to collagen fibers. There were differences in theoptical anisotropy of Ponceau SS-stained tendons from 21-day-old and 41-day-old chickens, indicat-ing that Ponceau SS was able to distinguish between different ordered states of macromolecularaggregation in chicken tendon collagen fibers. In the presence of dichroic rod-like azo-dye moleculessuch as Ponceau SS, collagen also formed structures with a much higher degree of orientation. Thepresence of LD in the Ponceau SS-collagen complex even in unpolarized light indicated that this com-plex can act as a polarizer.

The optical anisotropies (linear dichroism or LD and birefringence) of crystalline aggre-gates of the sulfonic azo-dye Ponceau SS and of dye complexed with chicken tendon collagen fiberswere investigated in order to assess their polarizing properties and similarity to liquid crystals. Insome...

The optical anisotropies (linear dichroism or LD and birefringence) of crystalline aggre-gates of the sulfonic azo-dye Ponceau SS and of dye complexed with chicken tendon collagen fiberswere investigated in order to assess their polarizing properties and similarity to liquid crystals. Insome experiments, the staining was preceded by treatment with picric acid. Crystalline fibrous aggre-gates of the dye had a negative LD, and their electronic transitions were oriented perpendicular tothe filamentary structures. The binding of Ponceau SS molecules to the collagen fibers altered the LDsignal, with variations in the fiber orientation affecting the resulting dichroic ratios. The long axis ofthe rod-like dye molecule was assumed to be bound in register, parallel to the collagen fiber. Picricacid did not affect the oriented binding of the azo dye to collagen fibers. There were differences in theoptical anisotropy of Ponceau SS-stained tendons from 21-day-old and 41-day-old chickens, indicat-ing that Ponceau SS was able to distinguish between different ordered states of macromolecularaggregation in chicken tendon collagen fibers. In the presence of dichroic rod-like azo-dye moleculessuch as Ponceau SS, collagen also formed structures with a much higher degree of orientation. Thepresence of LD in the Ponceau SS-collagen complex even in unpolarized light indicated that this com-plex can act as a polarizer.

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP

2003/04597-0

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ

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