Adsorption of bovine serum albumin onto magnetic chitosan microspheres

Magnetic chitosan nanoparticles(Fe2O3-CS) were prepared in microemulsion by crosslinking method. The transmission electron microscopy (TEM), Fourier transform infrared spectrophotometry (FT-IR) and vibrating specimen magnetometer (VSM) were used to characterize the nanoparticles. The mean diameter of the particles was about 40 nm with good dispersibility and magnetic response. The bovine serum albumin (BSA) was connected onto the surface of the magnetic nanoparticles with carbodiimide hydrochloride (EDC) as the activator. The products were then characterized by atomic force microscope (AFM) and ultraviolet spectrometer (UV). The results showed that the nanoparticles had a good adsorbability of the BSA. The adsorption isotherm of the BSA on the magnetic chitosan microspheres basicly obeyed the Langnmir model, with a maximum adsorption capacity of 250 mg center dot g(-1) and an adsorption equilibrium constant of 0.007 L center dot mg(-1). The stability of the particles-BSA complex in phosphate buffer solution (PBS) with different pH was also studied. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that BSA was desorbed from magnetic particles under alkaline condition.