SPR is the gold standard for binding kinetics — but what makes it so useful? Six concrete advantages that explain why SPR belongs in your analytical toolkit.
Surface Plasmon Resonance (SPR) is a biosensor technology used to detect biomolecular binding interactions in real-time. SPR biosensors have a variety of applications in life science, therapeutic drug monitoring, quality control, food, environmental testing, and beyond. SPR is used to monitor binding events between molecules ranging from proteins to small molecules. Among multiple biophysical techniques, SPR is the most commonly and widely used technology for several reasons.
1. Real-Time Monitoring
The best thing about SPR in monitoring biomolecular binding interaction (e.g. protein-protein) is that we can observe the association and dissociation of molecules in real-time. The computer software outputs the association and dissociation curves as a sensorgram — a plot of the SPR signal vs. time. Other techniques such as ELISA and co-immunoprecipitation only indicate whether binding is occurring or not, but SPR gives more detailed information about the binding process. It tells us about binding kinetics such as on and off rates, and affinity data critical for a deeper understanding of the process under investigation.
2. Label-Free Detection
One of the most important characteristics that makes SPR stand out is that it does not require any labeling as it is an optical technique. This is more accurate as there is no chance of the labels affecting the natural functionality of the ligand and/or analyte. Moreover, it saves costs by not using expensive fluorescent and radioactive labels, and other reagents required for labeled detection.
3. Small Sample Sizes
In a surface plasmon resonance experiment, the amount of sample size required is very small. Therefore, one would not require a lot of samples, especially if the yield resulting from protein purification is already low. In the same vein, less time is spent to acquire a purified sample for analysis.
4. Reusable Sensor Chips
The sensor chip used in an SPR experiment can be reusable, unlike the microwells used in ELISA. This saves both money and reduces waste. In an SPR experiment, a regeneration buffer can be used to dissociate the interaction between the ligand and analyte, and the sensors can be reused.
5. Use of Complex Samples
In most biological experiments, it is essential to purify the sample for accurate results and analysis; however, in SPR analysis, this is not true. SPR is an optical technique, and the light path does not cross the sample. Therefore, SPR analysis allows one to use both simple and complex samples such as serum, blood, plasma, and cell lysate.
6. Less Laborious and Short Experimental Time
A surface plasmon resonance instrument involves fewer washing and incubation steps compared to doing an immunoassay such as ELISA. Therefore, the length of an SPR run is much shorter; it takes minutes to a few hours to do an SPR experiment compared to hours or days for an ELISA.
Conclusion
Surface plasmon resonance technology is very useful to monitor biomolecular binding interactions in real-time. It has several advantages over other techniques such as real-time monitoring, label-free detection, small sample size requirement, reusable sensor chips, use of complex samples, and shorter experimental runs.