Azure Biosystems
Multiplexing fluorescent Western blots, also referred to as multiplex fluorescence, is the ability to detect multiple proteins simultaneously on the same blot. This allows you to get all the information you need at once. Fluorescent Western blotting uses secondary antibodies directly conjugated to fluorescent dyes.
Fluorophores for fluorescent Western blotting can be chosen based on their specific excitation and emission spectra, enabling multiplexing (Figure 1) for faster, more efficient studies. One of the biggest advantages of fluorescent detection versus chemiluminescence is the ability to use more than one antibody per assay (see the Table).
With multiplexing, normalization and loading controls can be imaged at the same time and on the same blot as the sample. The ability to use different fluorophores enables visualization of proteins that are not well-separated electrophoretically. This allows for more convenient imaging of the same protein with and without post-translational modifications.
| Advantages | Disadvantages |
|---|---|
| Multiplex capability | Can be less sensitive than chemiluminescence |
| Increased quantitative accuracy | Membranes' auto fluorescence can increase background |
| Fuorescent label stability allows blots to be stored and re-imaged later | Need an imager with multiplex protein detection |
| Fluorescent detection can provide a truly quantitative analysis of proteins in question | |
| Saves time |
Table 1. Advantages and disadvantages of fluorescent multiplex protein detection
Fluorescent Western blots are the gold standard for quantitative Westerns. Unlike chemiluminescent Westerns, which are limited by the variable kinetics of the enzyme-substrate reaction, the amount of light emitted from fluorophores is highly consistent and directly proportional to the amount of protein on the membrane. This consistency means that fluorescent detection can provide a truly quantitative analysis of the proteins in question.
The newer generation of imaging systems, including the new Azure Sapphire FL, often contain sophisticated cameras that exhibit a broader dynamic range than film, thus avoiding the signal saturation problems that limit the dynamic range of film. Fluorescent Westerns are typically visualized using a digital imager rather than X-ray film (Figure 2). Shown above is a fluorescent multiplex Western blot imaged using an Azure 600 imager. Finally, fluorescent dyes are relatively stable. Western blots can be archived and imaged months after the initial experiment as long as precautions are taken to avoid photo-bleaching of the fluorophores.
The Sapphire FL is capable of detecting up to four proteins on the same Western blot, which allows you to save money on each experiment. It uses 4 fluorescence channels to easily quantify overlapping bands. Multiple channels simplify normalization, which eliminates the need for stripping and re-probing. It offers simultaneous multichannel scanning to reduce your total imaging time. Learn more about the multiplex capabilities of the new Sapphire FL here.
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