Development of an immunosensor with angular interrogation-based SPR spectroscopy

We present a self-constructed immunosensor with angular interrogation-based-surface plasmon resonance (SPR) spectroscopy in order to analyse antigen–antibody interactions. The SPR intensity, resonance angle and full width at half maximum (FWHM) were significantly affected by the thickness of an Au film. The optimal thickness for the Au film thickness as an active metal for surface plasmons was determined to be approximately 45 nm, as respects the SPR intensity and the FWHM of SPR spectrum. The detection limit of the sensor based on the minimal refractive index variation was found to be 1.4 × 10−4. The interaction of C-reactive protein (CRP) with anti-CRP on a 45 nm Au film was successfully analysed with the self-constructed SPR sensor. We suggest that the SPR sensor can be used as a useful tool for the analysis of immunoreactions.