Investigation of Ferritin Desorption from Gold Initiated by In Situ pH-Change

One of the main questions regarding protein adsorption is about the reversibility of the adsorption process. To get a deeper understanding of this, adsorption of ferritin on Au was studied by quartz crystal microbalance and the pH of the buffer was changed in situ between two values that favour adsorption by different amounts. We found that although some ferritin desorbs from Au, the desorption is incomplete. When the desorption reached a constant value, we returned to the original conditions and investigated the readsorption. Our experiments show that the adsorption of ferritin onto Au is a partly reversible process. We found that for different initial ferritin coverages the proportion of ferritin that had been subsequently desorbed was approximately constant