Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (11): 2168-2176.doi: 10.3866/PKU.WHXB201409151

• BIOPHYSICAL CHEMISTRY • Previous Articles    

Adsorption Characteristics of Bovine Serum Albumin on Cationic Grafted Particles QPDMAEMA/SiO2 with Brush Structure

SHI Nan, GAO Bao-Jiao, YANG Qing   

  1. Department of Chemical Engineering, North University of China, Taiyuan 030051, P. R. China
  • Received:2014-06-16 Revised:2014-09-15 Published:2014-10-30
  • Contact: GAO Bao-Jiao
  • Supported by:

    The project was supported by the Natural Science Foundation for Young Scientists of Shanxi Province, China (2013021009-1).


Cationic grafted particles with a brush structure were prepared with micron-sized silica gel particles as a matrix via graft-polymerization and macromolecular reaction. The adsorption ability, adsorption mechanism, and adsorption thermodynamics of bovine serum albumin (BSA) on the particles were investigated in depth. The tertiary amine group-containing monomer (dimethylaminoethyl methacrylate, DMAEMA) was first allowed to polymerize on the surfaces of silica gel particles by initiating the ―NH2/S2O82- surface system, resulting in grafted PDMAEMA/SiO2 particles. Subsequently, the tertiary amine groups in the chains of the grafted PDMAEMA macromolecules were quaternized with chlorethamin reagent to obtain the functional grafted QPDMAEMA/SiO2 particles, on which the cationic polyelectrolyte QPDMAEMA macromolecules were grafted. The zeta potential of the QPDMAEMA/SiO2 particles was determined to estimate their surface electrical property. Isothermal adsorption experiments were carried out to investigate the effects of several main factors, including the pH value of the medium, ion strength, and temperature, on the adsorption performance of QPDMAEMA/SiO2 particles. Finally, the adsorption thermodynamics were investigated. The results showed that the functional grafted QPDMAEMA/SiO2 particles had much higher zeta potential than PDMAEMA/SiO2. BSA would be very strongly adsorbed on QPDMAEMA/SiO2 particles through electrostatic interactions. The adsorption capacity first increased and then decreased with increasing pH value, and it had a maximum value of 112 mg·g-1 when the pH value of the medium was equal to the isoelectric point of BSA (pI=4.7). On both sides of the isoelectric point, the effect of ion strength on the adsorption capacity was opposite. When the pH value of the medium was lower than the isoelectric point of BSA (i.e., pH<4.7), the adsorption capacity increased with increasing concentrations of electrolyte (NaCl). When the pH value of the medium was equal to the isoelectric point of BSA (i.e., pH=4.7), the adsorption capacity was almost unchanged with ion strength. The adsorption process was exothermic and during this process the entropy tended to decrease. Furthermore, this adsorption process was driven by enthalpy.

Key words: Polyelectrolyte brush, Bovine serum albumin, Dimethylaminoethyl methacrylate, Graft-polymerization, Electrostatic interaction, Adsorption


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