Can anybody give me his opinion in the reason why my sensorgram shows a small increase after injection which is followed by small decrease and completion of association and dissociation phases afterward (as shown in the attached figure specially
with the lower conc)?
The spike come from the fact that the channels are in series. When subtracting a reference, both channels are a little out of phase.
In the Biacore you can use the direct referencing during the experiment which will give less spikes.
Or you can adjust the injection time point t=0 for each curve.
When using a program like Scrubber, you kan artificially remove the spikes.
Large spikes occur mainly when the bulk effect is large (>25 RU) and the compensation by the reference channel is not optimal.