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 particl es stabilized by lauric acid. Then, magnetic agar gel beads were produced b y 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-bas ed magnetic affinity support (MAS) for protein adsorption. The support show ed 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 desc ribed 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 mu mol/mL. The effect o f ionic strength on BSA adsorption was complex, exhibiting a maximum capaci ty 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 x 10(-11) m(2)/s. Finally, recycled use of the MAS demonstrated the stab ility of the MAS in protein adsorption and magnetic responsiveness.