Label-free surface plasmon polariton application for labelled biomolecule detection

In this study, we present an experimental application of a label-free surface plasmon polaritons (SPP) method for the detection of CF®680 dye-labelled bovine serum albumin (BSA). We show the optical properties of the BSA-CF680 complex and the adsorption analysis of this bio-complex on the SPP sensing surface. The total internal reflection ellipsometry and fluorescence microscopy method were used to analyse the absorption and fluorescence properties of BSA-CF680. It was demonstrated that the SPP's quality factor increased when a labelled BSA-CF680 biomolecule complex was used compared to non-labelled BSA, indicating coupling between SPP and biomolecules. However, the number of biomolecules adsorbed to the surface shows that a higher emitter count or lower mode volume is required to reach the strong coupling regime. This approach of combining a label-free method with labelled biomolecules can pave the way for an alternative biomolecule detection method through spectral analysis.