BSA adsorption onto magnetic polyvinylbutyral microbeads

Bovine serum albumin (BSA) adsorption onto novel and feasible magnetic poly vinylbutyral-based microbeads was investigated. The microbeads were made of Mowital(R) B30HH, a commercial product, in the range 125-250 mum by a modi fied solvent evaporation technique. Magnetite particles were embedded in th e polymer structure for favorable magnetic properties, 4.80 emu/g microbead s of saturation magnetization at 6000 Gauss magnetic field. Glutaraldehyde (GA) was used as a bonding agent to increase stability and as a ligand for protein adsorption. The amount of adsorbed BSA was optimized by changing th e medium pH and the initial concentrations of GA and BSA. Dynamic adsorptio n data of batch runs fitted best to Langmiur kinetics. The parameters q(max ), k'(f) and k'(r) of the model were estimated through nonlinear regression analysis as 138 mg BSA/g adsorbent, 0.058 ml/(mg BSA . min) and 0.002 min( -1), respectively, for magnetic microbeads at pH 5.0 and 25 degreesC. The a dsorbed BSA was eluted successfully at pH 8.0 and 25 degreesC. Possibly due to surface roughness and magnetic properties, q(max) was found higher than the other adsorbents reported in the literature. The results denote that t hese microbeads can be an alternative protein adsorbent due to high adsorpt ion capacity and rate, as well as remarkable separation characteristics. (C ) 2001 John Wiley & Sons, Inc.