Label-free and real-time detection of specific binding of IgG proteins by oblique-incidence reflectivity difference method

The entire interaction process between anti-mouse immunoglobulin-G (IgG) and mouse IgG with a concentration range from 1 to 0.25 mg/mL has been label-free detected by the oblique incidence reflectivity difference (OIRD) method. We achieved the two-dimensional scanning images of OIRD Re{Δ p -Δ s } intensities before and after interactions as well as the curves of reaction dynamic processes. The experimental results suggest that OIRD method not only can label-free distinguish the different concentrations of proteins and detect biological microarrays, but also can real-time monitor the kinetic processes of biomolecular interactions.