Principle of the spectral discrimination is illustrated below. A polychromatic light beam excites surface plasmons along the metal – analyte (sensing channel A) and metal – dielectric overlayer (sensing channel B) interfaces. Due to the presence of the overlayer, SPR in the sensing channel B is shifted to longer wavelengths with respect to SPR in channel A. Hence, the spectrum of the reflected beam exhibits two SPR dips. By tracking location of the two SPR dips, both the sensing channels may be monitored simultaneously.

Figure 1. Dual-channel SPR sensor with spectral discrimination of sensing channels using a dielectric overlayer.

 

Using this sensor device we demonstrated detection of monoclonal anti dinitrophenyl (a-DNP). One of the sensing channel was functionalized for detection of a-DNP while the other was passivated to resist the no-specific binding. The resulting sensorgram shows a small amount of non-specifically adsorbed a-DNP is washed off when the sensor surface was rinsed with PBS, causing a slight drop in SPR wavelengths in both channels.

Figure 2. Detection of a-DNP using a dual-channel SPR sensor. Sensor response (upper plot). Response of specific sensor channel corrected for non-specific adsorption (lower plot).