Western blotting, ELISA and other assay techniques depend on probes that are detectable via chemical tags of one sort or another. Different types of chemical labels or tags can be conjugated to probes to facilitate their visualization (i.e., detection and measurement) by various methods. Radioactive isotopes, enzymes and fluorescent dyes are different types of chemical tags that have been used to make probes detectable. Choose the probe that is right for your application from the wide range we offer. For more information, review our Overview of Detection Probes

Antibodies as probes

Antibodies are the most common type of probe by virtue of their binding affinity for particular antigens which enable targets to be detected in a complex sample.

However, antibodies are not specifically detectable in an assay system unless they are tagged for visualization or secondarily probed with another molecule that is tagged. We offer a wide range of primary and secondary antibodies in purified (unconjugated) forms and as conjugates with HRP, AP, biotin and popular fluorophores.

Biotin binding proteins as probes

The highly specific affinity interaction between biotin (a small vitamin molecule) and avidin or streptavidin protein is the basis of detection in Western blotting. This form of indirect detection involves using a primary or secondary antibody that is labeled with a biotin affinity tag. Then a secondary (or tertiary) probe, such as streptavidin that is labeled with the detectable enzyme or fluorophore tag, can be used to probe for the biotin tag to yield a detectable signal.

We offer Streptavidin, NeutrAvidin® and avidin protein conjugates for biotinylated antibody probe detection in Western blot protocols including HRP and poly-HRP conjugates and high-intensity fluorescent and infrared conjugates.


Protein method

Fluorescent labels for detection

Fluorescence detection via fluorescent tags enables quantitative, multiplex analysis of western blots on your bench top - without the need for ECL optimization, film or a darkroom. Long-wavelength reporters like WesternDot™ probe antibodies are detected on membranes with high sensitivity and minimal background signal or scatter. Detect both strong and weak signals at the same time with a 4,000-fold linear dynamic range. With an appropriate reader, you can multiplex up to three probes on the same blot – providing an extra level of precision and biological context for your measurements.

Enzyme labels for detection

Enzymatic tags such as horseradish peroxidase (HRP) and alkaline phosphatase (AP) are most commonly used for Western blotting, immunoassays and immunohistochemistry methods.