Adsorption of Gelatin on Magnetic Iron Oxide Fine Particles

Adsorption of gelatin on magnetic iron oxide fine particles dispersed in water was carried out at 37°C. The amount of gelatin adsorbed on magnetic iron oxide fine particles was a maximum at pH 5.0 in the pH range of the aqueous dispersion containing gelatin and magnetic iron oxide fine particles. The amounts of adsorbed gelatin were measured at varying concentrations of NaCl. At pH 4.0, the amount of adsorbed gelatin was constant regardless of NaCl concentration. At pH 5.0 and 6.0, the amount of adsorbed gelatin decreased with increasing NaCl concentration. At pH 7.0, the amount of adsorbed gelatin increased with increasing NaCl concentration to 0.01 mol/dm3 and decreased with increasing NaCl concentration beyond 0.01 mol/dm3. The supernatant obtained by ultracentrifugation of the aqueous dispersion containing gelatin and magnetic iron oxide fine particles at pH 5.0 was analyzed using gel permeation chromatography. The average molecular weight of gelatin adsorbed on magnetic iron oxide fine particles increased with increasing initial gelatin concentration.