What is Thioflavin T fluorescence?
Thioflavin T (ThT) dye fluorescence is used regularly to quantify the formation and inhibition of amyloid fibrils in the presence of anti-amyloidogenic compounds such as polyphenols.
How does Thioflavin T bind to amyloid fibrils?
This suggests that positive charge on the thioflavin T molecule has a role in its micelle formation that then bind the amyloid fibrils. Our data suggests that the micelles of thioflavin T bind amyloid fibrils leading to enhancement of fluorescence emission.
How do you dissolve Thioflavin T?
Thioflavin T (ThT) is prepared by dissolving ~3 mg dry powder in 1 mL water. The solution is filtered through 0.22 μm syringe filters followed by measurement of the concentration by diluting the stock solution in ethanol and using an extinction coefficient of 26,620 M-1 cm-1 at 416 nm.
How does that bind to amyloid fibrils?
ThT binds to diverse fibrils, despite their distinct amino acid sequences, strongly suggesting that ThT recognizes a structural feature common among fibrils. Because amyloid fibrils share the cross-β architecture, it is generally accepted that the surfaces of cross-β structures form the ThT-binding sites.
What is the difference between Thioflavin T and S?
Thioflavin S
Like thioflavin T it binds to amyloid fibrils but not monomers and gives a distinct increase in fluorescence emission. However unlike thioflavin T, it does not produce a characteristic shift in the excitation or emission spectra.
Is Thioflavin T light sensitive?
In contrast, the fluorochrome dyes, thioflavin S and T, exhibit a dramatic increase in fluorescent brightness upon binding to amyloid. The binding of thioflavin dyes is linked to the presence of cross-β structure in the amyloid fibrils, and this stain is very sensitive.
What does Thioflavin T do?
Thioflavin T (ThT) is a commonly used probe to monitor in vitro amyloid fibril formation. Upon binding to amyloid fibrils, ThT gives a strong fluorescence signal at approximately 482 nm when excited at 450 nm [2].
What is Thioflavin T used for?
Thioflavins are fluorescent dyes that are available as at least two compounds, namely Thioflavin T and Thioflavin S. Both are used for histology staining and biophysical studies of protein aggregation. In particular, these dyes have been used since 1989 to investigate amyloid formation.
How does ThT bind amyloid?
The mechanism of fluorescence enhancement upon binding to amyloid has been attributed to the rotational immobilization of the central C–C bond connecting the benzothiazole and aniline rings [3–5]. It is commonly accepted that ThT binds to the side chain channels along the long axis of amyloid fibrils [6].
What is Congo red stain used for?
Staining with Congo Red (CR) is a qualitative method used for the identification of amyloids in vitro and in tissue sections.
What does Thioflavin S bind to?
Thioflavin S binds both senile plaques (SP) and neurofibrillary tangles (NFT), the two characteristic cortical lesions of Alzheimer’s.
Why is it called Congo red?
It’s believed that the marketing people at AGFA (a Berlin-based company, remember) came up with the name Congo Red for their new sensational dye because, to Europeans in 1885, the Congo was seen as an exotic place, a land of mystery, and the name ‘Congo’ was currently on the tip of every tongue due to the world-famous …
Is Congo red specific for amyloid?
Congo red, despite having lower sensitivity, is the standard agent used to identify amyloid in tissues. While the apple-green birefringence seen under crossed polarized light is specific for amyloid material, staining with Congo red is technically difficult resulting in inconsistent staining.
How do you make 0.2% of Congo red?
0.2% solution of Congo Red powder dye: • Dilute 0.1 g of Congo Red powder dye in 50 ml of solution of sodium chloride and alcohol. Add 0.5 ml od 1% potassium hydroxide. Filter before use. The mentioned formulation is only one of the ways of preparing the dye solution.
What is the principle of Congo red stain?
The Congo red staining principle is based on the formation of hydrogen bridge bonds with the carbohydrate component of the substrate. Congo red is an anionic dye and is capable of depositing itself in amyloid fibrils, which then exhibit a conspicuous dichroism under polarized light.
What is the purpose of Congo red dye?
Congo red was formerly used to dye cotton but has been superseded by dyes more resistant to light and to washing. It is still used in histology to stain tissues for microscopic examination, and to serve as an acid-base indicator, since it turns red in the presence of alkalies and blue when exposed to acids.
Why is Congo red stain used?
Staining with Congo Red dye (CR) is one of the major methods used to detect the amyloid structure of protein aggregates.
Is Congo red a negative stain?
Congo red (1% aqueous) Solution is used as negative stain for bacteria and spirochaetes.
Why is it called Congo red stain?
Conclusions: The Congo red stain was named “Congo” for marketing purposes by a German textile dyestuff company in 1885, reflecting geopolitical current events of that time.
Is Congo red basic or acidic?
acid-base
Congo red is an acid-base indicator dye.
Is Congo red a pH indicator?
“Congo red” is not the name of a famous African explorer, but a dye that dates to 1883. It was synthesized by P. Böttiger as a textile dye, but it subsequently became more important as a pH indicator. It colors aqueous solutions blue below pH 3.0 and becomes red above pH 5.0.