A surface plasmon resonance (SPR) biosensor based on wavelength modulation technology was developed and validated for the kinetic analysis of the interactions between two nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase-2 (COX-2). After the effect of different concentration COX-2 on the binding capacity of the SPR biosensor surface was studied, the COX-2 was immobilized covalently onto the biosensor surface using a standard amine coupling method. The affinity constants for indomethacin, ketoprofen binding to COX-2 are 7.5×103 L...