Interactions of proteins with uniform colloidal hematite and chromium hydroxide particles. II. Stability and mobility

Stability of hematite and chromium hydroxide particles covered by ovalbumin, -globulin, and lysozyme, respectively, and mobilities of the same coated particles in aqueous media were investigated as a function of the pH, ionic strenght [NaNO₃, Mg(NO₃)₂], and the amount of added proteins. It was found that ovalbumin causes electrosteric stabilization of dispersions at pH values other than 5, while flocculation occurred at pH 5 (which was the i.e.p. of the coated particles). Mobility curves of ovalbumin covered particles resembled those of the pure protein. Dispersions with -globulin flocculated at and around the i.e.p. of the macromolecule (pH7). The mobility curves of -gobulin-coated sols were intermediate between those of the protein and of the cores, and were dependent upon the amount of adsorbed -globulin. Heterocoagulation was observed for both hematite and chromium hydroxide dispersions with lysozyme. Mobilities of lysozyme covered particles were between those of the cores and of the protein, but were not dependent upon the quantity of adsorbed polymer.Supported by the NSF Grant CHE-9108420Part of a Ph.D. Thesis