F(AB')(2)-COATED POLYMER CARRIERS - ELECTROKINETIC BEHAVIOR AND COLLOIDAL STABILITY

The main goal of the present work is to gain insight into the mechanis ms and forces that govern the adsorption of F(ab')(2) fragments onto d ifferent polymer surfaces. We have employed F(ab')(2) fragments obtain ed by pepsin digestion of rabbit polyclonal IgG. Colloidal polystyrene particles with different superficial characteristics have been used a s polymer carriers. These latex particles differ in their hydrophobic/ hydrophilic character, surface charge density, and the nature of the i onic groups located at their solid-water interface. We have checked th at the most important driving force during the F(ab')(2) adsorption is the hydrophobic one. However, when adsorption isotherms are performed in media of low ionic strength, the electrostatic interaction plays a n important role. First, adsorption experiments carried out, followed by both desorption studies and electrokinetic characterization of the F(ab')(2)-latex complexes. The results of the electrokinetic character ization are in good agreement with those obtained from the stability s tudies. The research presented in this paper throws light on interesti ng aspects important when developing immunoassay reagents.