The mixture is incubated for 30 minutes at 25°C. After the incubation, 30 µL of Tris-HCl 1 M pH 8 were added, and the reaction was allowed to proceed for 5 minutes. The DBCOmodified streptavidin is then purified using Amicon Ultra 10MWCO centrifugal filters ( x 5 min at 13400 rpm) and finally PBS was added to bring the volume to 300 µL.