Why Does Single-Component TMB Chromogen Become the Preferred Substrate for HRP Detection Systems?

1. Blue Product Formation: HRP catalyzes the loss of electrons from TMB, forming a cation radical, which is further oxidized to generate a charge-transfer complex, presenting as a soluble blue color with maximum absorbance at 370 nm (some literature reports an absorption peak at 650 nm as well)

2. Acid Termination and Yellow Product: Upon addition of acidic stop solution (such as 0.5-2M H₂SO₄, 0.5M HCl, or 1M H₃PO₄), the blue product becomes protonated and transforms into a di-imine (dication), changing color from blue to yellow with maximum absorbance shifting to 450 nm

Operational Simplification

No preparation required; ready to use directly, avoiding manual operational errors

High Stability

Pre-mixed formulation maintains component compatibility through special stabilizers, with extended shelf life under 2-8°C protected from light

Reliable Results

Eliminates precipitation issues caused by improper preparation, significantly reducing inter-well variation (CV values)

Efficiency Enhancement

Particularly suitable for High-Throughput Screening (HTS) and automated workstations; 100 mL can detect approximately 1,000 ELISA samples

Standard/Regular Type

Suitable for routine ELISA quantitative analysis, featuring a wide linear range and low background characteristics. Room temperature color development time is typically 10-30 minutes, or 10-30 minutes at 37°C, suitable for most routine detections.

Super Sensitive Type

Specifically designed for detecting low-abundance antigens or weak antibody reactions. Offers the highest color development efficiency among TMB substrate series, producing obvious blue signals within 2-10 minutes. Recommended for:

• Qualitative detection (such as antibody screening, positive clone identification)
• ELISA detection of low-expression proteins
• Rapid detection workflows requiring shortened color development time

Broad Range Type

Optimized for dynamic detection range, capable of detecting both high and low concentration samples simultaneously without easy saturation. Particularly suitable for:

• Quantitative ELISA analysis
• Precise quantitative experiments requiring standard curve establishment
• Batch detection with large sample concentration differences

Membrane Blotting Dedicated Type

Specifically designed for membrane immunodetection experiments such as Western Blot, dot blot, Southern Blot, and Northern Blot. Unlike ordinary soluble TMB, the membrane-dedicated type produces purple insoluble precipitate at reaction sites, with extremely low or no background, and can be terminated directly with water (no strong acid required), avoiding damage to nitrocellulose or PVDF membranes from strong acids.

Preparation:

• Remove single-component TMB chromogen from 2-8°C refrigerator and equilibrate to room temperature (if containing glycerol components, warm in 37°C water bath until liquid state)
• Ensure chromogen is clear and colorless; if turbidity or blue color appears indicating oxidation and failure, discontinue use

1. Thorough Washing

After HRP-labeled antibody incubation, wash with PBST (PBS containing Tween-20) or TBST 3-5 times, 3-5 minutes each, to completely remove unbound enzyme-labeled antibody (this is key to reducing background)

2. Add Chromogen

Remove wash solution, add 100 μL single-component TMB chromogen per well

3. Protected from Light Incubation

Incubate at room temperature (20-37°C) protected from light for 5-30 minutes, or extend up to 24 hours according to experimental requirements, until color develops to expected intensity (blue)

Note: Color development time needs optimization based on antigen-antibody affinity; excessive development (>30 minutes) may lead to increased background

4. Reading or Termination

• Direct Reading: Measure absorbance at 370 nm wavelength (suitable for kinetic analysis)
• Terminated Reading: Add 100 μL 0.5-2M H₂SO₄ to terminate reaction; color changes from blue to yellow, measure absorbance at 450 nm (recommended to complete reading within 30 minutes after termination to avoid yellow product degradation)

Enzyme-Linked Immunosorbent Assay (ELISA):

• Antigen/hapten quantitative detection (such as cytokines, hormones, pathogen proteins)
• Antibody titer determination (such as vaccine immunization efficacy evaluation)
• Positive clone identification in drug screening and antibody drug development

Membrane Blotting Immuno-detection:

• Western Blot: Qualitative detection of protein expression; TMB chromogenic bands can be preserved long-term (photographic documentation), no darkroom or film required
• Dot Blot: Rapid screening of positive clones or detection of nucleic acid/protein samples
• Southern/Northern Blot: HRP chromogenic detection after nucleic acid hybridization

Histochemistry:

HRP chromogenic detection in immunohistochemistry (IHC) for localization observation of specific proteins in tissue sections

Safety Protection:

• Single-component TMB chromogen contains TMB and H₂O₂, which are irritating to skin and mucous membranes
• Laboratory coat, disposable gloves, and protective eyewear must be worn during operation
• In case of accidental skin contact, immediately rinse with copious amounts of water

Chromogenic Control:

• High Background: Check if blocking is sufficient (recommend 5% skim milk or BSA), if washing is thorough, and if secondary antibody concentration is too high
• No Color or Weak Color: Check if HRP-labeled antibody is inactivated, if chromogen has failed (turned blue or turbid), or if color development time is insufficient
• Uneven Color Development: Ensure chromogen uniformly covers the well bottom, avoiding bubble formation

Special Tips:

• Protected from Light Storage: TMB is light-sensitive; unused chromogen should be immediately returned to 2-8°C protected from light to avoid oxidation
• Termination Timing: For super sensitive TMB, closely monitor color development process and terminate immediately when ideal color intensity is reached to prevent signal saturation
• Membrane Blotting Dedicated Type: After water termination, photograph immediately; do not store long-term to avoid precipitate diffusion