Effects of water loading on the fluorescein/anti-fluorescein antibody system in aerosol-OT reverse micelles formed in n-heptane

We report on the behavior of monoclonal 4-4-20 mouse anti-fluorescein antibodies sequestered within aerosol-OT (AOT) reverse micelles formed in liquid n-heptane as a function of water loading (R). Our data suggest that the fluorescein binding site structure is unaffected by R. However, we note that there is a region, at intermediate R values, where the fluorescein apparently binds even more strongly to the monoclonal anti-fluorescein antibodies compared to the native antibody in solution. These results are qualitatively explained in terms of the Ruckenstein-Karpe model, which is based on charge disproportionation and redistribution within the reverse micelle. The results demonstrate that R, within an AOT reverse micelle, influences the apparent anti-fluorescein affinity.