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Congo red fluorescence upon binding to macromolecules – a possible explanation for the enhanced intensity

Zemanek G., Jagusiak A., Chłopaś K., Piekarska B.

Bio-Algorithms and Med-Systems

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2017

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Vol. 13, no. 2

69--78

EN

The present study attempts to explain the reason for the selective generation of an increase in intensity of Congo red (CR) fluorescence as an effect of the dye interacting with proteins and polysaccharides. This supramolecular dye, which creates ribbon-shaped micelles in aqueous solutions when excited with blue light (470 nm), presents low fluorescence with a maximum within the orange-red light range (approximately 600 nm). In the same conditions, CR-stained preparations of heat-denatured proteins, some native proteins (e.g. cell surface receptors) and cellulose show intense orange-red fluorescence when observed using a fluorescence microscope. The fluormetric measurements showed that the factors that cause the dissociation of the ribbon-shaped CR micelle – ethanol, urea, dimethyl sulfoxide (DMSO) and cholate – all contributed to a significant increase in the fluorescence intensity of the CR solutions. The fluorescence measurements of CR bound to the immunoglobulin light lambda (L λ) chain and soluble carboxymethyl cellulose (CMC) showed a fluorescence intensity which was many times higher. In the case of the denatured (65°C) immunoglobulin L λ chain, the fluorescence intensity significantly exceeded the values observed for the factors which break down the CR micelles. The dissociation of the ribbon-shaped micelles and the complexation of the monomeric CR form with polymers are two of the factors explaining the intense fluorescence of protein and polysaccharide preparations stained with CR.

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Shortening and dispersion of single-walled carbon nanotubes upon interaction with mixed supramolecular compounds

Jagusiak A., Piekarska B., Chłopaś K., Bielańska E., Pańczyk T.

Bio-Algorithms and Med-Systems

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2016

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Vol. 12, no. 3

123--132

EN

Congo red (CR) dye molecules self-associate in water solutions creating ribbon-like supramolecular structures that can bind various aromatic compounds by intercalation, forming mixed supramolecular systems. Mixed supramolecular systems, such as CR-doxorubicin and CREvans blue, interact with the surface of carbon nanotubes, leading to their stiffening and ultimately to their breaking and shortening. This work presents a simple method of obtaining short and straight carbon nanotubes with significantly better dispersion in aqueous solutions and consequently improved usability in biological systems.

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The use of Titan yellow dye as a metal ion binding marker for studies on the formation of specific complexes by supramolecular Congo red

Chłopaś K., Jagusiak A., Konieczny L., Piekarska B., Roterman I., Rybarska J., Stopa B., Zemanek G., Bielańska E., Piwowar P., Sadlik K.

Bio-Algorithms and Med-Systems

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2015

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Vol. 11, no. 1

9--17

EN

Congo red (CR) and other self-assembling compounds creating supramolecular structures of rod- or ribbon-like architecture form specific complexes with cellulose and also with many proteins, including antibodies bound to the antigen and amyloids in particular. The mechanism of complexation and structure of these complexes are still poorly recognized despite the importance of the problem for medicine. This work proposes the progress in electron microscopy studies of amyloid-dye complexes by labeling supramolecular ligand CR with silver ions as a marker. Silver ions are introduced to CR carried by the strongly binding silver dye Titan yellow, which in addition form comicellar structures with CR. Silver carried by self-assembled dye molecules forms in the resulting metal nanoparticles, making the specific amyloid ligand CR perceptible in EM studies.