Assessment of Refractive Index-Based SPR Sensor for Branched Chain AA

This study reports an investigation on the detection of one of the essential branched-chain amino acids (AA) named leucine. The detection is done by using two different configurations of surface plasmon resonance (SPR) sensors, such as Probe1 (silver/graphene oxide (GO)/leucine dehydrogenase/leucine) and Probe2 (gold/GO/leucine dehydrogenase/leucine). The transfer matrix method (TMM) is used to analyze the performance of the sensors. The analysis of both the sensor probes is done in the presence of RI ranging from 1.3373 to 1.3425. The detected RI range is considered at two different temperatures of 298.15 K and 308.15 K which corresponds to lower and normal human body temperatures. The results show that the maximum sensitivity of Probe1 and Probe2 is 261.54°/RIU and 192.31°/RIU, respectively, attained at 308.15 K. Additionally, the quality factor, detection accuracy (DA), and full-wave half maximum (FWHM) of Probe1 and Probe2 at 308.15 K are 33.97, 0.04, 7.70, and 119.45, 0.16, 1.63, respectively. Furthermore, the field confinement in metallic layers is studied by using two-dimensional Opti-FDTD software.