Surface plasmon is an optic process that is used to detect molecular interaction. The binding of a mobile substance (analyte) to the molecule that is immobilized on a thin film of metal (ligand) alters its refractive index. Light's angle of extinction reflecting after polarized light is impinging on the film is altered and recorded by a change in the detector location for the decrease in intensity of reflection. 

Since the technique only detects mass it is not necessary to label the components that interact which eliminates the possibility of changes in their molecular characteristics. The surface plasmon resonance (SPR) method of binding analysis is employed to study the molecular interaction. You can know more about Anti-SPR antibody picoband from Boster bio.

SPR is an optical method to detect the interaction between two different molecules where one is mobile, and the other is fixed by the surface of a thin gold film. In the research described in this paper, affinity-purified fusion polypeptides are bound by an amine-coupling reaction in the sensor chip inserted into the flow chamber of the Biacore 3000 instrument. 

SPR can directly measure mass (concentration) and does not call for any special fluorescence or radioactive labeling of the polypeptides before measuring, offering the advantage of minimizing time and complexity of research. Surface plasmon resonance (SPR) analysis was used to assess the immune reactivity of anti-biotin  and anti-fluorescein monoclonal antibody after conjugation with the N-hydroxysuccinimide ester of acridinium-9-carboxamide 1.