Amyloids, Congo red and the apple-green effect

Abstract

This paper attempts to find evidence of the previously proposed opinion that amyloids complex with Congo red molecules which preserve their supramolecular organization. As evidence of the overpowering tendency of Congo red molecules to self-assemble, we present an increasing acidity of molecules that follows increasing concentration of the dye, and a highly notable nonlinear increase in absorbance in the UV band (300–400 nm). This effect is analyzed in a model where the amyloid fibril is simulated by polyvinyl alcohol, providing a scaffold to stabilize a long Congo red micelle. Enormous absorbance in the UV band, coupled with the increasing association capabilities of individual Congo red molecules may cause the absorbance to extend even into the visible band. In addition, the UV and visual absorbance bands shift significantly, depending on conditions, and may either approach or recede from each other, leading to spectral changes which may be observed under polarized light. This commonly observed spectral variability appears to be associated with the strong capacity for electron delocalization in supramolecular Congo red complexed with amyloids.

Application study of infrared free-electron lasers towards the development of amyloidosis therapy

“…2). It is well known that Congo-red binds to -sheet stacks of amyloid fibrils and emits green-yellow birefringent light (Jagusiak et al, 2019). Before the IR-FEL irradiation [left, Fig.…”

К Вопросу О Вторичном Амилоидозе Почек При Ювенильном Ревматоидном Артрите У Детей

“…Для уточнения генеза нефротического синдрома всем детям проведено прижизненное морфологическое исследование почек, что позволило диагностировать у них АА-амилоидоз. В биоптатах почек, окрашенных конго красным, в поляризованном свете амилоид изменяет красный цвет окраски на яблочнозеленое свечение, которое обнаруживается в клубочках и мозговом слое почек [40]. Ряд авторов подчеркнули низкую информативность ректальной биопсии для диагностики АА-амилоидоза почек [10,29].…”

The ASC inflammasome adapter controls the extent of peripheral protein aggregate deposition in inflammation-associated amyloidosis

“…CC-BY-NC-ND 4.0 International license made available under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is The copyright holder for this preprint this version posted May 2, 2021. ; https://doi.org/10.1101/2021.05.01.442282 doi: bioRxiv preprint -- (64). In light microscopy, amyloid appears as pink amorphous material (black arrows).…”