Explain the operation of a surface plasmon resonance (SPR) sensor in biochemistry.
1 Answer
Surface Plasmon Resonance (SPR) is a powerful sensing technique used in biochemistry to study molecular interactions in real-time without the need for labels or complex sample preparations. The principle behind SPR is based on the unique behavior of surface plasmons, which are oscillations of electrons that occur at the interface between a metal and a dielectric material (usually glass).
Here's how an SPR sensor works in biochemistry:
Sensor Setup: The SPR sensor consists of a thin metal film, commonly gold or silver, deposited on a glass substrate. This thin metal layer is coated with a layer of immobilized biomolecules, such as antibodies, proteins, DNA, or other ligands that can selectively bind to the target molecules of interest.
Prism-Coupling Configuration: The SPR sensor operates under the prism-coupling configuration. A prism made of a high refractive index material (typically glass or BK7 glass) is placed on top of the metal-coated surface at a specific angle of incidence. This configuration allows light to be coupled into the metal film through the prism.
Incident Light: A monochromatic light (usually a laser) is directed onto the backside of the prism, which leads to total internal reflection at the prism-metal interface. The angle of incidence is adjusted to a specific value known as the resonance angle, where the phase of the reflected light becomes sensitive to any changes occurring at the metal-dielectric interface.
Plasmon Resonance: When the resonance angle is reached, the incident light energy couples with the surface plasmons, resulting in their resonance. The surface plasmons create an evanescent wave that extends into the dielectric layer (sample solution) above the metal surface.
Sample Interaction: When a sample containing analyte molecules is introduced to the sensor surface, the analytes can bind to the immobilized biomolecules on the metal surface. The binding of analytes causes a change in the local refractive index at the metal-dielectric interface.
Detection: The binding events or molecular interactions on the metal surface result in a shift in the resonance angle or a change in the intensity of the reflected light. These changes can be detected and measured in real-time using a detector, providing information about the kinetics, affinity, and concentration of the molecular interactions occurring on the sensor surface.
Data Analysis: By monitoring the changes in the SPR signal over time, researchers can obtain valuable information about the association and dissociation rates of the biomolecular interactions, allowing them to characterize the binding specificity and strength between analytes and immobilized ligands.
Overall, SPR sensors offer label-free, non-destructive, and real-time monitoring capabilities, making them widely used in various applications within biochemistry, such as studying protein-protein interactions, antigen-antibody binding, DNA hybridization, drug discovery, and more.
Here's how an SPR sensor works in biochemistry:
Sensor Setup: The SPR sensor consists of a thin metal film, commonly gold or silver, deposited on a glass substrate. This thin metal layer is coated with a layer of immobilized biomolecules, such as antibodies, proteins, DNA, or other ligands that can selectively bind to the target molecules of interest.
Prism-Coupling Configuration: The SPR sensor operates under the prism-coupling configuration. A prism made of a high refractive index material (typically glass or BK7 glass) is placed on top of the metal-coated surface at a specific angle of incidence. This configuration allows light to be coupled into the metal film through the prism.
Incident Light: A monochromatic light (usually a laser) is directed onto the backside of the prism, which leads to total internal reflection at the prism-metal interface. The angle of incidence is adjusted to a specific value known as the resonance angle, where the phase of the reflected light becomes sensitive to any changes occurring at the metal-dielectric interface.
Plasmon Resonance: When the resonance angle is reached, the incident light energy couples with the surface plasmons, resulting in their resonance. The surface plasmons create an evanescent wave that extends into the dielectric layer (sample solution) above the metal surface.
Sample Interaction: When a sample containing analyte molecules is introduced to the sensor surface, the analytes can bind to the immobilized biomolecules on the metal surface. The binding of analytes causes a change in the local refractive index at the metal-dielectric interface.
Detection: The binding events or molecular interactions on the metal surface result in a shift in the resonance angle or a change in the intensity of the reflected light. These changes can be detected and measured in real-time using a detector, providing information about the kinetics, affinity, and concentration of the molecular interactions occurring on the sensor surface.
Data Analysis: By monitoring the changes in the SPR signal over time, researchers can obtain valuable information about the association and dissociation rates of the biomolecular interactions, allowing them to characterize the binding specificity and strength between analytes and immobilized ligands.
Overall, SPR sensors offer label-free, non-destructive, and real-time monitoring capabilities, making them widely used in various applications within biochemistry, such as studying protein-protein interactions, antigen-antibody binding, DNA hybridization, drug discovery, and more.