DAB Solution (1 mg/mL, pH 3.8) - BioReagent

Cat. No.: D1528816

GRADE & PURITY BioReagent

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Overview

DAB Solution is a fluorescence-based assay reagent intended for the quantitative determination of hydrogen peroxide. The assay principle is based on the peroxidase-mediated oxidation of 10-acetyl-3,7-dihydroxyphenoxazine (ADHP) by hydrogen peroxide, yielding the highly fluorescent product resorufin. The resulting fluorescence intensity, measured with a microplate reader, is directly proportional to the hydrogen peroxide concentration in the sample. This product is specifically developed for the quantification of hydrogen peroxide in plant tissues, with particular applicability to leaf samples, and is suitable for studies addressing oxidative stress, stress physiology, and signal transduction pathways.

Specifications

Specifications & Purity

BioReagent

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

This product requires cold chain shipping. Ground and other economy services are not available.

Grade

BioReagent

Product Line

Biological Products

Application Protocols

• General notes: The following are representative, literature-derived workflows. Optimize for your samples and detection chemistry.

• IHC/ICC with HRP–DAB (literature guidance):

  1. Prepare tissue sections; deparaffinize and rehydrate if FFPE. Perform antigen retrieval as required.
  2. Block endogenous peroxidase (e.g., 0.3–3% H2O2 in buffer, 10–20 min), then rinse.
  3. Block nonspecific binding; incubate with primary antibody.
  4. Apply HRP-labeled secondary detection system; wash thoroughly.
  5. Immediately before use, combine the supplied DAB solution with fresh H2O2 to the desired working level.
  6. Incubate sections with DAB/H2O2, monitoring color development (typically 1–10 min).
  7. Stop by rinsing in water; counterstain (e.g., hematoxylin) if desired.
  8. Dehydrate (graded ethanols), clear (xylene), and mount with permanent medium.

• Western blot HRP–DAB (literature guidance):

  1. Following transfer and blocking, incubate blot with primary and HRP-conjugated secondary antibodies; wash.
  2. Incubate membrane in freshly prepared DAB/H2O2 working solution until bands appear (minutes); agitate gently.
  3. Stop by rinsing with water or buffer; air-dry or image immediately.

• Controls: Include no-primary and no-HRP controls to assess background and substrate auto-oxidation.

Biological Roles

• This product is a synthetic chromogenic substrate solution and does not have a physiological biological role.
• Mechanistic context (literature, general): In bioassays employing HRP as a reporter enzyme, DAB acts as an electron donor in the presence of hydrogen peroxide, enabling localization of antigen–antibody complexes via formation of an insoluble brown polymer at enzyme sites.
• Histological implications (general): The precipitated product is stable to typical dehydration and clearing steps, allowing long-term archiving of IHC slides for retrospective studies and quantitative image analysis.
• Endogenous interference: Many tissues possess endogenous peroxidase activity (e.g., erythrocytes, myeloid cells). Appropriate H2O2 pretreatment can reduce background prior to DAB development (protocol-dependent; literature guidance).

Buffer Applications

• Not a buffering reagent. This product is a ready-to-use chromogenic substrate solution for HRP-based detection.
• Practical note: If dilution or formulation adjustments are necessary, maintain mildly acidic conditions near the supplied pH to preserve stability, and avoid strong bases or amine-rich buffers that can promote non-enzymatic oxidation (literature, general).

Green Alternatives

• Considerations: DAB-based systems are effective but raise safety and waste-management concerns typical of aromatic diamines and peroxidase substrates. Greener or safer alternatives may be appropriate depending on assay requirements (literature, general).
• Potential alternatives (literature):
  • TMB (3,3′,5,5′-tetramethylbenzidine): Often considered less hazardous; produces a blue product (ELISA) or, in precipitating formulations, a blue/teal deposit for blots/tissue. Alcohol sensitivity varies by formulation.
  • AEC (3-amino-9-ethylcarbazole): Red deposit; soluble in alcohols (not permanent through dehydration). Avoids permanent brown staining but requires aqueous mounting.
  • DAB-Ni/Co intensification variants: Not greener but offer higher contrast; weigh added metal waste burdens.
• Selection trade-offs:
  • DAB: Brown, permanent, alcohol/xylene-stable; robust archiving; stricter handling/waste controls.
  • TMB: Safer profile, good sensitivity, but permanence and solvent resistance depend on kit/formulation.
  • AEC: Vivid red for multiplex contrast; not solvent-stable—limits tissue processing options.
• Practical guidance: Choose based on permanence, color contrast, downstream processing (dehydration/clearing), and institutional EHS guidance. Validate alternative substrates in your specific tissue and detection chemistry before wholesale replacement.

Pharmaceutical Uses

• Not intended for pharmaceutical formulation or clinical/diagnostic applications. For research use only (item-specific note).
• No pharmacopeial status is claimed for this product. Any use in GMP or regulated contexts would require independent qualification and validation by the end user.

Physical Properties

• Physical state: Aqueous solution (item-specific context as a solution product; exact solvent system not specified).
• Concentration: 1 mg/mL (item-specific)
• pH: 3.8 (item-specific)
• Density, refractive index, viscosity: Not specified for this item; refer to CoA/Spec Sheet.
• Solubility: As supplied in aqueous medium (item-specific). Further solubility parameters not specified for this item; refer to CoA/Spec Sheet.
• UV/Vis characteristics (literature, general): DAB substrates are weakly yellow in solution; upon HRP/H2O2 reaction, an intense brown insoluble product forms with broad absorbance in the visible range. Exact extinction coefficients for this formulation are not specified.
• Stability notes: Acidic pH supports improved shelf-stability of DAB stock by slowing spontaneous oxidation (literature, general). Protect from light and metal contamination to minimize background oxidation (practical guidance).
• Boiling point, melting point, vapor pressure, logP, pKa: Not specified for this item; refer to CoA/Spec Sheet.

Quality & Grades

• Grade: BioReagent (item-specific)
  • Meaning (general): BioReagent grade denotes suitability for common life-science workflows (e.g., IHC, immunoblotting, enzyme localization) where low background and consistent performance are prioritized. It does not imply clinical/diagnostic use.
• Item-specific quality implications:
  • Pre-formulated at 1 mg/mL and pH 3.8 to provide consistent chromogenic performance lot-to-lot in HRP-based detection (item-specific).
  • Supplied as a solution to reduce handling errors associated with weighing hygroscopic/oxidation-sensitive solids (practical note).
• Stabilizers/inhibitors: Not specified for this item; refer to CoA/Spec Sheet.
• UV cutoffs/impurity limits/metal limits: Not specified for this item; refer to CoA/Spec Sheet.
• Documentation: For method validation or regulated environments, obtain the CoA/Spec Sheet for lot-specific details (conformance, traceability).

Reaction & Applications

• Core application: Chromogenic detection of horseradish peroxidase (HRP) activity in immunohistochemistry (IHC), immunocytochemistry (ICC), in situ hybridization (ISH; HRP-based), and Western blotting (WB). DAB yields a durable, brown, alcohol-insoluble deposit at enzyme sites (literature, general).
• Reaction chemistry (literature): HRP catalyzes the H2O2-dependent one-electron oxidation of DAB to reactive radicals/quinonediimines that rapidly couple/polymerize, precipitating at the site of enzyme activity. The deposit can be further darkened with nickel or cobalt salts (intensification) when compatible.
• Practical tips:
  • Work fresh: Mix DAB with the required H2O2 immediately before use; discard after the session to limit background.
  • pH control: Maintain near the supplied pH (~3.8) to improve shelf-stability of the working stock; final reaction typically proceeds well in mildly acidic to neutral media (protocol-dependent, literature).
  • Background suppression: Thorough washing post-secondary antibody, minimize endogenous peroxidase activity with H2O2 quenching where appropriate, and avoid metallic tools.
  • Microscopy: DAB product is compatible with standard mounting media and withstands ethanol dehydration and xylene clearing; ideal for permanent brightfield records (literature).
• Electron microscopy (literature): DAB polymer can be osmiophilically enhanced with OsO4 to yield high-contrast EM labeling of peroxidase reporters.

Reaction Conditions

• Intended use: HRP-catalyzed chromogenic development on membranes, cells, or tissue sections (research use).
• Typical working conditions (literature, general guidance):
  • DAB concentration: 0.2–1.0 mg/mL in water or buffer.
  • H2O2: 0.003–0.03% (w/v or v/v, depending on stock) freshly added before use.
  • Temperature: Ambient (20–25°C).
  • Incubation: Monitor development visually; 1–10 minutes is common, depending on HRP load and matrix.
  • Termination: Rinse thoroughly with buffer or water to stop the reaction.
• Enhancements (literature): Nickel or cobalt salts can darken the product to near-black for increased contrast; validate compatibility with specimen and counterstains.
• Practical tips:
  • Prepare working solution immediately before use to limit background.
  • Use plastic coplin jars or passivated glassware to minimize metal-catalyzed auto-oxidation.
  • Filter the working solution (0.22–0.45 µm) if particulate background is observed.
• Expected performance: Provides a permanent brown, alcohol/xylene-stable signal suitable for brightfield microscopy and archiving (literature).

Safety & Handling

• GHS classification, pictograms, hazard statements, signal word: Not specified for this item; refer to the SDS.
• General hazards (literature, general): Aromatic diamines, including DAB, can be harmful and are handled with caution in research settings. The oxidation product is an insoluble pigment—avoid inhalation/ingestion of particulates if dried residue is generated. Handle solutions in a chemical fume hood.
• PPE: Lab coat, nitrile gloves, and splash-resistant safety goggles. Change gloves frequently when handling peroxidase substrates and H2O2.
• Incompatibilities (general): Strong oxidizers and transition-metal contaminants can trigger non-enzymatic oxidation; minimize contact with metals (iron, copper) and avoid bleach in waste that contains residual DAB. Avoid strong bases which can accelerate degradation.
• Peroxide/substrate handling: Prepare peroxide working solutions freshly. Add H2O2 to DAB immediately before use to limit background development (practical guidance).
• First-aid overview (general): In case of skin/eye contact, rinse with water for at least 15 minutes; remove contaminated clothing. If inhaled, move to fresh air. If swallowed, rinse mouth with water. Seek medical attention as per SDS.
• Waste: Collect DAB-containing waste separately and dispose in accordance with institutional and local regulations. Do not discharge to drains. Always defer to your EHS office and the SDS for authoritative instructions.

Solvent Selection

• Applicability: This product is an aqueous DAB solution used directly for HRP-driven chromogenic development; external solvent selection is typically unnecessary.
• Polarity/miscibility: As supplied in water at pH 3.8 (item-specific). If dilution is required, use high-purity, metal-free deionized water or compatible buffer at similar acidity to maintain stability (practical guidance).
• Compatibility notes (general, literature):
  • Avoid amine-rich, strongly basic buffers that elevate pH; they can increase non-enzymatic oxidation and background.
  • Minimize exposure to trace metals (Fe, Cu) that can catalyze oxidation; use plastic disposables or passivated glassware.
  • Organic cosolvents are generally unnecessary; alcohols can influence deposition morphology and should be avoided unless protocol-validated.
• When to choose this format: A pre-made acidic DAB solution simplifies IHC/IF-peroxidase and immunoblot workflows where reproducibility and convenience are valued. Choose powder forms only if you require custom concentrations or buffer systems.

Storage & Reconstitution

• Storage conditions: Store at -20°C (item-specific). Keep tightly closed. Protect from light to limit auto-oxidation.
• Shipping: Shipped in an ice chest with ice pads (item-specific).
• Format: Ready-to-use aqueous solution at 1 mg/mL, pH 3.8 (item-specific). No reconstitution required.
• Handling:
  • Thaw on ice or at 2–8°C; mix gently to ensure homogeneity. Do not vortex excessively to avoid aeration.
  • Aliquot upon first thaw to minimize freeze–thaw cycles; avoid repeated freeze–thaw.
  • Use clean, metal-free plasticware to reduce catalytic oxidation.
• On-bench stability: Not specified for this item; refer to CoA/Spec Sheet. As general practice, prepare the H2O2-containing working solution immediately before use and discard after the session.
• Shelf life: Not specified for this item; refer to CoA/Spec Sheet.
• Re-freezing: Permissible in aliquots; avoid multiple cycles. If discoloration or precipitate appears before use, prepare fresh working solution and validate performance.

Structure & Identity

• Item type: Ready-to-use peroxidase substrate solution, commonly known as DAB Solution (3,3′-diaminobenzidine-based), formulated at 1 mg/mL and pH 3.8. (item-specific)
• Concentration: 1 mg/mL (item-specific)
• pH: 3.8 (item-specific)
• Molecular formula: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
• SMILES / InChI / InChIKey: Not specified for this item; refer to CoA/Spec Sheet.
• Structural features (general, literature): DAB is a biphenyl core bearing aromatic amine substituents; upon peroxidase-catalyzed oxidation, it forms a brown, insoluble, polymeric deposit at enzyme sites. This product presents DAB in a stabilized, acidic aqueous medium suitable for HRP-based chromogenic development.
• 2D description (general, literature): Two phenyl rings linked (biphenyl) with amino groups on each ring; the electron-rich anilines enable rapid one-electron oxidation by HRP/H2O2 to quinonoid species that couple to yield an insoluble pigment.

Synthetic Utility

• This item is not a general synthetic building block but a prepared peroxidase substrate solution for bioassays.
• Relevant chemistry (literature, general): Aromatic diamine oxidation by HRP/H2O2 generates quinonediimine intermediates that undergo radical coupling/polymerization to yield an insoluble pigment. While mechanistically instructive, this chemistry is leveraged for visualization rather than preparative synthesis.
• Cross-linking context: The localized polymerization at enzyme sites can entrap biomolecules and enhance signal permanence, which is valuable in histological workflows but is not typically exploited in synthetic organic routes.

Target Specificity

• Not an antibody or affinity reagent. This product has no intrinsic target specificity.
• Signal localization arises from the distribution of HRP-conjugated probes (e.g., secondary antibodies, streptavidin–HRP) bound to the target of interest in the user’s assay (literature, general).