Label-free kinetic study of biomolecular interactions by white light reflectance spectroscopy

Binding of biomolecules in real-time is studied by white light reflectance spectroscopy (WLRS). The experimental apparatus consists of a WLRS setup and a microfluidic channel for the supply of the biomolecules solutions placed above the sample on which the biomolecular interactions take place. Using this setup, it is possible to monitor in real-time the biomolecular film thickness changes during the binding of biomolecules on a properly treated surface. The sample is a silicon wafer with a thick thermally grown silicon dioxide (~1044 nm) and a thin (~35 nm) polymer layer. The proposed methodology has been applied for the monitoring of streptavidin binding to surface-immobilised biotinylated protein. The biomolecular interactions are monitored as shifts of the wavelength where constructive interference is observed. The proposed methodology provides a simple, fast, low cost approach for a label-free monitoring of biomolecular interactions