SPR interaction for small molecules

Did you modify the reference or is it native carboxyl and hydroxyl groups?
Which type/brand of chip are u using?

It can be beneficial to activate and block the reference with ethanolamine of other small amine components.

Thanks for your comment, Well, I did EDC/NHS activation on channel 1(in which I immobilize the protein) and did ethanol amine capping on both channels. I used, SensiQ gold only chips from icx nomadics. SAM was prepared by myself.
Do I need to do EDC/NHS activation on both channels?

The activation does what it say. Activation of the sensor surface so it can bind other molecules. In case of the NHS/EDC the carboxyl groups of your SAM are modified so that the next injection with primary amines (such as ethanol amine) will bind. Without activation no immobilization.

I suggest you look at www.sprpages.nl/immobilization.htm for a detailed description.

Thanks for your comments. So far I have been activating with EDC/NHS only in channel one (where I Immobilize the protein) and I did the ethanol amine injection on both channels. I guess as per your comments, I have to activate both channels ( including reference channel ) with EDC/NHS and then de-activate with ethanol amine on both channels right? Let me do in this way and see what happens.
Preejith SLC

I am trying to use SPR to study the interaction of small molecules ( my compounds are hydrophobic and sticky) with its binding protein. I am getting too much of nonspecific binging on the reference channel, so its hard to extract the specific binding. I used a mixed carboxyl and hydroxyl SAM to bind the protein Does anyone got experience with these kinds of molecule interaction using SPR?
Preej