Agar-Based Magnetic Affinity Support for Protein Adsorption

Magnetic colloidal particles were prepared by a coprecipitation method. The particles were composed of nanometer‐sized superparamagnetic Fe3O4 particles stabilized by lauric acid. Then, magnetic agar gel beads were produced by a water‐in‐oil emulsification method using a mixture of agar solution and the magnetic colloidal particles as the aqueous phase. A reactive triazine dye, Cibacron blue 3GA (CB), was coupled to the gel to prepare an agar‐based magnetic affinity support (MAS) for protein adsorption. The support showed good magnetic responsiveness in a magnetic field. Bovine serum albumin (BSA) was used as a model protein to test adsorption equilibrium and kinetic behavior of the MAS. The adsorption equilibrium of BSA to the MAS was described by the Langmuir‐type isotherm. Adsorption capacity of the MAS for BSA was up to 25 mg/mL at a CB coupling density of 1.6 μmol/mL. The effect of ionic strength on BSA adsorption was complex, exhibiting a maximum capacity at an ionic strength of 0.06 mol/L. The adsorption of BSA to the MAS was also influenced by pH. Uptake rate of BSA to the MAS was analyzed using a pore diffusion model. The pore diffusion coefficient was estimated to be 1.75 × 10−11 m2/s. Finally, recycled use of the MAS demonstrated the stability of the MAS in protein adsorption and magnetic responsiveness.