Integration of a multichannel surface plasmon resonance sensor chip and refractive index matching film array for protein detection in human urine

Abstract

Most prism-based surface plasmon resonance (SPR) experiments use matching fluid with a similar refractive index to mount the chip on the optical prism. The fluidity of the matching fluid easily affects the transmission of the optical signal. In this paper, an integrated SPR sensor chip comprises a three-layer structure of flow layer, metal layer and refractive index matching layer is demonstrated to address the problems related to consistency and uniformity. The Young's modulus, array spacing, shape and other parameters of the matching film were calculated and optimized. The chip can self-adhere to the optical prism, and effectively avoids the generation of air bubbles. The refractive index detection sensitivity of the integrated SPR sensor chip was 3.4359 × 10−6 RIU (refractive index unit), and the chip stabilization time has been effectively shortened. The integrated SPR sensor chip was also used to detect kappa light chain protein and human serum albumin (HSA) in urine samples. The detection limit of kappa light chain protein was 0.06 μg/mL compared with 18.5 μg/mL by conventional immunoturbidimetry. The integrated SPR sensor chip based on refractive index matching film array has great potential in biomedical detection and other fields, including point-of-care testing (POCT).