Noise reduction by multiple referencing in surface plasmon resonance imaging.

The analytical performance of surface plasmon resonance imaging with charge coupled device detection can be improved significantly by splitting a macroscopic sensing surface into multiple microscopic neighboring sensing and referencing subareas. It is shown that such a multiple referencing reduces intensity fluctuations across the total sensing area and, therefore, improves the signal/noise (S/N) ratio proportional to the splitting factor. The approach is demonstrated by detection of biotin binding to a monolayer of streptavidin. An effective variation of the reflected intensity of about 10(-4), which corresponds to the refraction index variation of 3x10(-6), was detected with a S/N ratio about 10 without any temperature stabilization of the sensing area.