Amyloid Staining Solution (Puchtler Alkaline Congo Red Method) - BioReagent,for microscopy,Biological Stain

Cat. No.: A1508466

GRADE & PURITY BioReagent, Biological Stain, for Microscopy

Synonyms

Amyloid Staining Solution

Storage

Protected from light,Room temperature

Shipped In

Normal

Application

Cell Staining

Visão geral

Amyloid is an amorphous extracellular eosinophilic substance that can be present in various tissues and organs, and the diseases caused by it are referred to as amyloidosis. Amyloid is mainly composed of proteins, most of which are arranged in an antiparallel β-pleated sheet structure. Under an electron microscope, amyloid exhibits a fibrillary arrangement, appearing as a large number of unbranched extracellular filaments in pathological specimens, mostly arranged randomly. Histological methods for identifying amyloid include methyl violet staining, Congo red staining, and polarized light microscopy. Current research has demonstrated that the traditional methyl violet staining method has low sensitivity and poor specificity, while Congo red staining is a classic and effective approach. In 1922, Bennhold discovered that Congo red could be used for the identification of amyloid in vivo and applied this technique to tissue sections.

Amyloid Staining Solution (Puchtler Alkaline Congo Red Method) is mainly composed of Congo Red Staining Solution and Hematoxylin Staining Solution. Its staining principle lies in that amyloid has a higher affinity for Congo red than other tissue structures, and its hydroxyl groups bind to the amino groups of Congo red, thereby staining amyloid red. This staining method has stable performance and is a very classic technique for amyloid staining. This reagent is for research use only and is not suitable for clinical diagnosis or any other purposes.

A1508466	Component	4×50 mL	Storage
A1508466A	Hematoxylin Staining Solution	50 mL	RT. Store in the dark.
A1508466B	Acid Ethanol Differentiating Solution	50 mL	RT
A1508466C	Sodium Chloride Solution	50 mL	RT
A1508466D	Congo Red Staining Solution	50 mL	RT. Store in the dark.
A1508466E	Puchtler Alkalizing Solution	1 mL	RT

Materials to be Prepared by User

1. 10% neutral formalin, distilled water, graded ethanol

2. Xylene or environment-friendly paraffin removal and clearing solution, neutral balsam, Scott's Bluing Solution

Procedure (for reference only)

1. Perform routine fixation. There is no special requirement for the fixative; 10% neutral formalin fixative is commonly used, followed by routine dehydration and embedding.

2. Cut sections with a thickness of 4 μm, and perform routine dewaxing to water using xylene or dewaxing and clearing solution.

3. Immerse the sections in Hematoxylin Staining Solution for 5 min.

4. Differentiate with Acid Ethanol Differentiating Solution for 2-5 s, immediately transfer the sections to water to terminate differentiation, wash twice with water, and check under a microscope to ensure appropriate differentiation.

5. Rinse with tap water for 2 min.

6. Immerse the sections in Scott's Bluing Solution or rinse with water for bluing, then rinse with tap water for 2 min.

7. Prepare alkaline sodium chloride solution at a ratio of sodium chloride solution: Puchtler alkalizing solution=100:1. Prepare it immediately before use. Immerse the sections in the alkaline sodium chloride solution for 20 min.

8. Prepare alkaline Congo red staining solution at a ratio of Congo red staining solution: Puchtler alkalizing solution=100:1. Prepare it immediately before use. Directly immerse the sections in the alkaline Congo red staining solution for 20 min.

9. Rinse gently with anhydrous ethanol, clear the sections with xylene or dewaxing and clearing solution, and mount them with neutral balsam.

Staining Results

Amyloid: Red

Cell Nucleus: Blue

Precautions

1. Ensure thorough dewaxing of sections; otherwise, the staining effect will be affected.

2. Store Acid Ethanol Differentiating Solution in a sealed container and use it as soon as possible after opening.

3. Prefer immersion staining when using Congo Red Staining Solution; if drop staining is adopted, place the sections in a moist chamber to prevent solution evaporation.

4. Prepare alkaline sodium chloride solution and alkaline Congo red staining solution immediately before use, and try to use them within 20 min.

5. For your safety and health, wear a lab coat and disposable gloves during operation.

6. Use the reagent as soon as possible after opening to avoid affecting the results of subsequent experiments.

Specifications

Sinónimos

Amyloid Staining Solution

Especificações e pureza

BioReagent,for microscopy,Biological Stain

Estabilidade e armazenamento

Each component has a shelf life of 1 year under corresponding storage conditions. A1508466A、A1508466D: Store at room temperature long term (12 months). Store in the dark. A1508466B、A1508466C、A1508466E: Store at room temperature long term (12 months).

Condições de armazenamento de armazenamento

Protected from light,Room temperature

Enviado em

Normal

Grau

Biological Stain, BioReagent, para microscopia

Product Line

Produtos biológicos

Propriedades químicas e físicas

• Sensibilidade: Light-sensitive

Application Protocols

Item-specific validated protocols and dilutions: Not specified for this item; refer to CoA/Spec Sheet or product label.

General/literature workflow for Puchtler alkaline Congo red staining (for research planning; not item-specific)

• Deparaffinize sections and rehydrate to water.
• Optional pre-treatment: some protocols include alkaline salt pre-rinse to reduce background (details vary).
• Stain in alkaline Congo red solution for a defined period (optimize empirically based on formulation strength and tissue thickness).
• Rinse briefly in alkaline solution; avoid acid.
• Counterstain with hematoxylin if desired; blue in alkaline solution.
• Dehydrate rapidly through graded ethanols, clear, and mount with a non-aqueous medium.
• Examine under brightfield and crossed polarizers for birefringence.

Controls and QC

• Include known positive and negative control tissues in each run.
• Record lot numbers, exposure times, and temperatures to ensure reproducibility.

Note

• Adapt times and steps to your laboratory SOPs and the actual composition provided on the item’s CoA/label.

Biological Roles

Scope

• This section summarizes the biological context of the target of this stain—amyloid fibrils—to assist research planning. It does not imply clinical use.

General background (literature; not item-specific)

• Amyloid refers to protein aggregates adopting cross-β-sheet architectures. Diverse precursor proteins can form amyloid (e.g., Aβ peptides, transthyretin, serum amyloid A), leading to extracellular fibrillar deposits in tissues.
• Congo red binds amyloid via noncovalent interactions (electrostatic and π–π stacking) along the β-sheet grooves; ordered binding produces characteristic birefringence under polarized light.
• The affinity is influenced by pH, ionic strength, and solvent composition; alkaline conditions often improve selective binding and reduce background from collagen.

Research applications (non-clinical)

• Mapping distribution and maturation of amyloid deposits in animal models and ex vivo tissues.
• Correlating brightfield/polarized Congo red staining with other markers (e.g., immunohistochemistry against amyloidogenic proteins) to validate aggregate identity.
• Evaluating effects of experimental treatments on amyloid burden in preclinical studies.

Caveats

• Congo red can also bind non-amyloid β-sheet–rich structures; stringent controls, polarization microscopy, and orthogonal methods (e.g., fluorescence dyes, IHC) are recommended to confirm specificity in research.

Buffer Applications

Applicability

• While this product is a formulated staining solution, successful use depends on the buffers and rinses employed before and after staining.

Item-specific buffer specs

• Solution pH and buffer composition: Not specified for this item; refer to CoA/Spec Sheet.

General/literature guidance for Puchtler alkaline Congo red workflows (not item-specific)

• Pre-conditioning: bring sections to distilled water after deparaffinization and rehydration through graded ethanols.
• Alkalinity: use alkaline buffers or alkaline alcohol rinses to sustain dye–amyloid interaction; avoid acidic solutions post-stain.
• Salt content: controlled ionic strength can suppress nonspecific collagen staining while preserving amyloid signal; specifics vary by protocol.
• Counterstain and blueing: if using hematoxylin, follow with alkaline blueing (e.g., Scott’s tap water substitute) rather than acidic differentiators that can strip Congo red.

Practical tips

• Use freshly prepared or well-preserved buffers to avoid microbial growth and pH drift.
• Maintain consistent temperature; some protocols note reduced background at room temperature with minimal variation.
• Run positive/negative control slides with each batch to confirm buffer performance and stain selectivity.

Green Alternatives

Context

• Congo red–based amyloid staining solutions can involve azo dyes and alcoholic solvents. While effective, these may raise concerns regarding VOC emissions and dye-containing wastewater.

Potential greener strategies (general; not item-specific)

• Reduce VOCs: prefer aqueous or lower-alcohol alkaline formulations where performance allows; cover staining dishes and limit open-bath durations.
• Alternative probes: Thioflavin T/S (fluorescent) enable lower mass loadings and aqueous protocols, reducing solvent use; tradeoff is need for fluorescence instrumentation and different specificity profiles.
• Process efficiency: adopt closed staining systems, reuse validated working solutions for limited cycles with QC checks, and scale volumes to slide throughput to minimize waste.
• Waste management: segregate azo dye waste for appropriate disposal; implement activated carbon polishing of aqueous effluents if permitted by local regulations.

Illustrative comparison (literature-based; performance varies)

• Alkaline Congo red (brightfield + polarized):
  • Pros: classic morphology visualization; birefringence readout; compatible with routine microscopes.
  • Cons: potential alcohol VOCs; azo dye wastewater; sensitive to pH and mounting conditions.
• Thioflavin T (fluorescence):
  • Pros: high sensitivity; typically aqueous; small volumes.
  • Cons: requires fluorescence optics; different false-positive/negative profile; not directly comparable to birefringence.

Note

• Select “greener” alternatives only after confirming they meet your research objectives and QC requirements.

Pharmaceutical Uses

Not typically applicable.

• This product is a research-use-only histology staining solution intended for laboratory microscopy. It is not an excipient or manufacturing aid with pharmacopeial monographs.
• If considering use in regulated environments (e.g., nonclinical GLP studies), validate the staining method, document lot traceability, and obtain the CoA/Spec Sheet. No therapeutic, diagnostic, or clinical claims are implied.

Physical Properties

Item-specific properties

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Concentration, solvent system, pH, and dye content: Not specified for this item; refer to CoA/Spec Sheet.
• Density, refractive index, viscosity: Not specified for this item; refer to CoA/Spec Sheet.
• Boiling point (solution), flash point, freezing point: Not specified for this item; refer to CoA/Spec Sheet.

General/literature values (not item-specific; for context only)

• Congo red (solid dye) literature data: MW ≈ 696.7 g/mol (disodium salt); highly water-soluble due to sulfonate groups; strong absorbance in the visible red region. These values pertain to the neat dye, not to this formulated solution.
• Puchtler alkaline solutions are often alkaline and may contain alcohol and electrolytes to control background and specificity; the exact formulation and physical constants vary by manufacturer/preparation.

Notes for users

• Because this is a formulated staining solution, its physical properties depend on the solvent blend and concentration chosen by the manufacturer. For rigorous method validation (e.g., GLP/GMP environments), consult the CoA/Spec Sheet for pH, solvent composition, and any stabilizers, and verify compatibility with tissue processing reagents and mounting media.

Quality and Grades

Item-specific facts

• Grade: BioReagent, Biological Stain, for Microscopy (per Product Data).

What this grade generally implies (general guidance)

• Biological Stain grade indicates suitability for microscopy and histology workflows, emphasizing consistent coloration characteristics, low particulate matter, and compatibility with tissue processing steps (deparaffinization, hydration, counterstaining, mounting).
• BioReagent designation typically reflects quality appropriate for research use, with attention to lot reproducibility and minimized interfering impurities that could affect staining specificity or background.

Practical quality considerations for amyloid staining solutions

• For Congo red–based methods, key performance attributes include: stable alkaline pH, controlled dye concentration, low background on collagen, and preservation of birefringence under polarized light. These are performance characteristics rather than guaranteed specifications unless listed on the CoA.
• UV cutoff, metal content, and trace impurities: Not specified for this item; refer to CoA/Spec Sheet.
• Stabilizers/preservatives: Not specified for this item; refer to CoA/Spec Sheet.

Documentation and QC

• For method validation, capture lot number and verify results on known positive and negative control tissues. Request the CoA/Spec Sheet for any required numeric specifications (pH, dye %, solvent composition).

Reaction and Applications

Scope for this product

• This section focuses on laboratory APPLICATIONS rather than chemical synthesis, as the product is a formulated amyloid staining solution for microscopy.

Item-specific applications

• Manufacturer text: Not specified beyond the name. Intended use: research use only (per Product Data).

General/literature applications of the Puchtler alkaline Congo red method (not item-specific)

• Selective staining of amyloid deposits in formalin-fixed, paraffin-embedded tissue sections. When properly executed, amyloid appears salmon-red in brightfield and exhibits apple-green birefringence under crossed polarizers.
• Used to evaluate amyloid distribution and morphology in research models (e.g., transgenic animal tissues, experimental deposits in organotypic cultures) and to confirm the presence of β-sheet–rich aggregates.

Practical tips (general)

• Use known positive control tissue (e.g., liver/spleen with established amyloid) alongside negatives for QC.
• Maintain the solution protected from light (as required for this item) to avoid dye degradation; filter before use if particulates are seen (0.45 μm PTFE or nylon, as compatible).
• Control pH and ionic strength of rinses; alkaline conditions favor binding and preservation of birefringence.
• Avoid strong acidic steps after staining; acids can elute dye from amyloid and reduce polarized signal.
• Minimize prolonged aqueous exposure after staining to preserve intensity and birefringence; proceed efficiently to dehydration and mounting.

Reaction Conditions

Not directly applicable as a chemical reaction reagent.

General/literature workflow parameters for Puchtler alkaline Congo red staining (not item-specific; for research planning)

• Section preparation: deparaffinize; rehydrate to water.
• Staining: immerse in alkaline Congo red solution for a defined period (often several minutes up to ~30 min, depending on formulation and tissue). Exact time for this item is not specified; refer to CoA/Spec Sheet or validated lab SOPs.
• Rinsing/differentiation: brief rinse in alkaline water/alcohol to reduce background; avoid acids.
• Counterstain: optional hematoxylin; blue in alkaline solution.
• Dehydration/mounting: dehydrate through graded ethanols, clear, and mount with non-aqueous, low-acid medium to preserve birefringence.

Expected outcomes (general)

• Amyloid deposits: salmon-red in brightfield; apple-green birefringence under crossed polarizers when method is optimal.

Notes

• Temperature, pH, and ionic strength are critical variables; validate conditions with control tissues.
• Because composition and strength of this item are not specified in the Product Data, determine staining time empirically upon receipt, beginning with conservative exposures and adjusting based on control outcomes.

Safety and Handling

Item-specific hazard data

• Signal word, H-statements, GHS classification, pictograms: Not specified for this item; refer to SDS.
• Storage conditions: Protected from light; Room temperature (per Product Data). Ship: Normal.

General/literature safety guidance (not item-specific; consult SDS for authoritative data)

• Amyloid staining solutions for the Puchtler method commonly contain an azo dye (e.g., Congo red) and may be alkaline and/or alcohol-containing. Potential hazards include skin/eye irritation, staining, and solvent-related flammability if alcohol is present.
• Recommended PPE: lab coat, nitrile gloves, safety glasses; work in a well-ventilated area or fume hood to minimize inhalation of aerosols or solvent vapors.
• Incompatibilities (general): strong oxidizers; avoid contact with acids/bases outside intended pH if the solution contains alcohols or salts that could degrade. Prevent contact with light to minimize dye photodegradation (as directed for this item).
• First aid (general):
  • Skin: wash with soap and water; remove contaminated clothing.
  • Eyes: rinse cautiously with water for several minutes; seek medical attention if irritation persists.
  • Inhalation: move to fresh air; seek attention if symptoms occur.
  • Ingestion: rinse mouth; do not induce vomiting; seek medical advice.
• Spill/cleanup: absorb with inert material; avoid release to drains; dispose as hazardous chemical waste according to institutional and local regulations.
• Always defer to the product-specific SDS and institutional safety policies.

Solvent Selection

Applicability to this product

• This is a formulated staining solution rather than a neat solvent. Solvent selection principally concerns its compatibility with upstream and downstream histology steps.

Item-specific solvent details

• Exact solvent composition/miscibility: Not specified for this item; refer to CoA/Spec Sheet.

General/literature guidance for Puchtler alkaline Congo red workflows (not item-specific)

• Pre-treatment: sections are typically deparaffinized in xylene or substitutes and hydrated through graded alcohols to water.
• Staining bath: the Congo red solution is often alkaline and may be aqueous-alcoholic to optimize amyloid affinity and reduce background. Maintain consistent temperature to minimize precipitation or shade variation.
• Rinsing/differentiation: brief rinses in alkaline alcohol or buffer can improve contrast; avoid acidic washes that may reduce birefringence.
• Counterstains: common choices include Harris hematoxylin; ensure solvent compatibility to prevent dye desorption.
• Mounting: to preserve birefringence, use non-aqueous, low-acid mounting media; excessive water exposure post-stain can diminish Congo red–amyloid signal.

Comparison notes (general)

• Aqueous-only formulations are simpler and lower in VOCs but may show higher background on collagen.
• Alcohol-containing alkaline formulations can enhance specificity and reduce background but increase flammability and VOC considerations.

Storage and Reconstitution

Item-specific storage

• Storage conditions: Protected from light; Room temperature (per Product Data).
• Shipping: Normal.

Reconstitution/use

• The product name suggests a ready-to-use solution, but the presence of concentrates or working-strength status is Not specified for this item; refer to CoA/Spec Sheet.
• If supplied as a concentrate (general guidance), bring to volume with the specified solvent/buffer under light-protected conditions and mix thoroughly. Filter (0.45 μm) if particulates are observed, using a membrane compatible with the solvent system.

Handling and stability (general)

• Minimize light exposure during storage and use to reduce dye photobleaching or degradation; keep container tightly closed to limit evaporation if volatile solvents are present.
• Avoid contamination: pour small working aliquots; do not return used solution to the stock container.
• Stability/shelf life, precipitation limits, and freeze–thaw guidance: Not specified for this item; refer to CoA/Spec Sheet.

Before first use

• Inspect for clarity, homogeneity, and label information (lot, any stated pH or solvent). Verify performance on a control slide before running experimental samples.

Structure and Identity

Item-specific facts (from Product Data)

• Product type: Amyloid Staining Solution for the Puchtler Alkaline Congo Red method (histology/microscopy stain mixture)
• Grade: BioReagent, Biological Stain, for Microscopy
• CAS, InChIKey, SMILES, Molecular formula, Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.

General/literature background (not item-specific)

• The Puchtler alkaline Congo red method uses an alkaline, often alcoholic, Congo red solution to stain amyloid deposits in fixed tissue sections. The key chromophore is an azo dye (Congo red) with extended π-conjugation enabling birefringence under polarized light.
• Typical structural features of Congo red (literature): disazo framework linking two naphthalene units bearing sulfonate groups (water solubilizing) and amino substituents; planar, highly conjugated system responsible for red coloration and apple-green birefringence when bound to amyloid fibrils.
• As a ready-to-use solution, the product is a mixture; a single molecular identifier is therefore generally inapplicable.

2D structural description (literature)

• Congo red presents two parallel aromatic systems connected by azo (–N=N–) linkers; terminal sulfonate groups (as sodium salts) render the dye anionic at neutral/alkaline pH, facilitating electrostatic and hydrophobic interactions with amyloid β-sheet surfaces. (Description provided for context; not a specification of this item’s exact composition.)

Synthetic Utility

Not applicable.

• This product is a formulated staining solution for microscopy, not a discrete synthetic building block or reagent. It is not typically employed as a reactant, catalyst, or solvent in chemical synthesis.
• For information on using Congo red or related dyes as spectroscopic probes in solution chemistry (e.g., indicator applications), consult general literature; such uses are separate from the intended histology application of this item.

Target Specificity

Not applicable to antibodies or affinity reagents.

• This product is a histological staining solution and does not have attributes such as antigen clone, epitope mapping, isotype, or species reactivity.
• Specificity considerations are methodological: under appropriate alkaline conditions, Congo red preferentially highlights amyloid fibrils and exhibits birefringence; confirmation with polarized light and orthogonal methods is recommended in research.