Coupling antibodies or proteins to a gold surface by passive adsorption is fairly easy, at least at small scale. First, you need to determine the optimal coupling pH by screening pH values from 6 to 9.
The second step consists of finding the right antibody or protein concentration to stabilize your gold nanoparticles and avoid aggregation. Protein concentrations in the range of 3 to 5 µg/ml/OD usually work well. The stability of your gold conjugates can be estimated and compared by addition of Sodium Chloride to the medium and subsequent observation of the aggregation tendency of the conjugate.
The optimal antibody or protein concentration is the one that does not result in, even after adding salts, change to the ruby color of the gold particles. If you need more information, please contact us. We will help you to ensure the success of your conjugate development.