Adsorption of BSA on carbon-coated Fe3O4 microspheres activated with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride

Carbon-coated Fe 3 O 4 (Fe 3 O 4 /C) microspheres activated with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) were prepared, characterized and applied to adsorb bovine serum albumin (BSA). The prepared magnetic microspheres had spherical core-shell structure with a uniform and continuous carbon coating coupled with activation by EDC, and possessed superparamagnetic characteristics. The experimental results showed that the adsorption amount of BSA on the EDC-activated Fe 3 O 4 /C (Fe 3 O 4 /C-EDC) microspheres was higher than that on the Fe 3 O 4 /C microspheres. The maximum adsorption of BSA on Fe 3 O 4 /C-EDC microspheres occurred at pH 4.7, which was the isoelectric point of BSA. At low concentrations (below 1.0 M), salt had no noticeable effect on BSA adsorption. The BSA adsorption of Fe 3 O 4 /C-EDC microspheres had a better fit to the Langmuir model than the Freundlich isotherm and Temkin isotherm model, and the kinetic data were well described by the pseudo-second-order model. The adsorption equilibrium could be reached within 20 min. High desorption efficiency (97.6%) of BSA from Fe 3 O 4 /C-EDC microspheres was obtained with 0.5 M Na 2 HPO 4 (pH 9.4) as the desorbent.