What does Congo red staining do to the amyloid molecule?

Staining with Congo Red dye (CR) is one of the major methods used to detect the amyloid structure of protein aggregates. However, a series of experiments have shown that CR staining is insufficient for confirmation of the amyloid nature of protein aggregates.

What does Congo red detect?

Congo red is still the standard stain used in most histopathology laboratories to identify amyloid material in tissues. The identification of Congophilic amyloid material is challenging because of multiple interfering factors.

How do you make a 1% Congo red solution?

2.2. Preparation of Congo Red 1000 mg/L (stock solution) was prepared by dissolving 1 g of congo red in 1 Liter of distilled water. 20, 40, 70 and 100 ppm solution prepared by dilution from the stock solution.

How does Congo red work?

Congo red was formerly used to dye cotton but has been superseded by dyes more resistant to light and to washing.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.

What are the procedures for the Congo red assay?

Congo Red spectrophotometric assay is more objective, less prone to misinterpretation, and can be easily combined with the microscopic analysis. Procedures for Congo Red birefringence assay: 1. Prepare the staining solution: prepare a solution of 80% EtOH: 20% DDI water and add a saturating amount of NaCl.

When to use Congo red as a pH indicator?

Congo red ( pH indicator) below pH 3.0. above pH 5.2. 3.0. ⇌. 5.2. Due to a color change from blue to red at pH 3.0–5.2, Congo red can be used as a pH indicator. Since this color change is an approximate inverse of that of litmus, it can be used with litmus paper in a simple parlor trick: add a drop or two of Congo red to both an acid solution

How to use Congo red in a microscope?

Congo Red can be used straight from the manufacturer or can be recrystallized from 50% EtOH: 50% DDI water prior to use. The staining solution should be used immediately or stored in 0.05% sodiumazide to inhibit bacterial growth. 2. Air-dry 10µL of the aggregated protein solution onto a glass microscope slide. 3.

What’s the best way to stain Congo red?

1. Place the coverslip with section in a ceramic staining rack . 2. Immerse sections in Harris Hematoxylin for 30 seconds to one (1) minute. 3. Wash with tap water until the water is clear. 4. Filter the Congo Red solution into a columbia staining dish (Thomas Scientific#8542-E40) 5.