Data Processing of SPR Curve Data to Maximize the Extraction of Changes in Electrochemical SPR Measurements

Abstract

We developed a novel measuring and data-processing method for performing electrochemical surface plasmon resonance (EC-SPR) on sensor surfaces for which detecting a specific SPR angle is difficult, such as a polymer having a non-uniform thickness with coloration. SPR measurements are used in medicine and basic research as an analytical method capable of molecular detection without labeling. However, SPR is not good for detecting small molecules with small refractive index changes. The proposed EC-SPR, which combines SPR measurements with an electrochemical reaction, makes it possible to measure small molecules without increasing the number of measurement steps. A drawback of EC-SPR is that it is difficult to detect a specific SPR angle on electron mediators, and it was found that it may not be possible to capture all the features produced. The novel method we describe here is different from the conventional one in which a specific SPR angle is obtained from an SPR curve; rather, it processes the SPR curve itself and can efficiently aggregate the feature displacements in the SPR curves that are dispersed through multiple angles. As an application, we used our method to detect small concentrations of H2O2 (LOD 0.7 μM) and glutamate (LOD 5 μM).

Surface plasmonic biosensors: principles, designs and applications

“…However, for conventional small molecules, it is difficult for SPR to detect the change in angle occurring due to the small RI change caused. Inoue et al combined electrochemical reactions with SPR to monitor changes in the measurement process from the perspective of the curve data themselves, while the measurement steps remain unchanged 45 (Fig. 2c).…”

“…44 (c) Electrochemical-SPR measurement mechanism. 45 (d) Schematic diagram of a hyperspectral SPR microscope system. 46 Because an alteration in RI causes an equal alteration in the SPR wavelength and angle, the range of their change may be widened to increase the sensor's sensitivity.…”