Practice question

Surface Plasmon Resonance monitors binding kinetics in real-time on a gold-coated sensor chip without labels. Ligand is covalently immobilized on dextran matrix, analyte flows over. Incident polarized light excites surface plasmons; resonance angle depends on refractive index near surface. When analyte binds ligand, local mass concentration increases, altering refractive index and shifting resonance angle, recorded as resonance units versus time. Temperature fluctuations or UV are minimized and electric fields are not relevant; angle shift predominantly reflects binding-induced refractive index change.