I’m using an SPR device with an SA chip. The immobilized ligand is FcGammaRI, and I want to evaluate the kinetics and affinity of VEGF binding to Avastin. I would like to know how I should arrange my method. Should I inject Avastin first and then VEGF? Should I use only one concentration of Avastin and different concentrations of VEGF, or vice versa? Or should I prepare my method in a different way?