App note: AN2 sensitive protein quantification in serum – comparison of FO-SPR and ELISA

By April 23, 2021No Comments

Application note 2 | Kim Stevens, Kris Ver Donck, Filip Delport
Based on original publication: Lu et al. (2016) Biosensors and Bioelectronics 79, 173–179. (1)


This application note demonstrates the potential of FOx BIOSYSTEMS’ fiber-optic surface plasmon resonance technology (FO-SPR) for determining the concentration of a protein or antibody in crude samples, like serum. As an example, we demonstrate the detection of the therapeutic monoclonal antibody, infliximab (IFX), in patient serum samples. FO-SPR is a powerful tool that harnesses the power of SPR in an easy-to-use fiber-optic sensor.

The methods described here demonstrate that FO-SPR, enhanced with a gold nanoparticle sandwich-style bioassay, can detect biologically relevant concentrations of infliximab. IFX levels in patient serum are typically between 0.5 – 10 µg/ml, and the lower detection limit of this assay was 0.25 ng/ml or 1.7pM in 100-fold diluted patient serum. Furthermore, there is an excellent correlation between results obtained by FO-SPR and those using an optimized ELISA technique (Pearson correlation 0.998 and intraclass coefficient 0.982).

We discuss how the FO-SPR sandwich-style assay can provide a fast and accurate alternative to ELISA for the analysis of biomolecules in crude samples with minimal processing, thereby showing great potential as an R&D tool.