Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (02): 359-366.doi: 10.3866/PKU.WHXB20100207

• CATALYSIS AND SURFACE STRUCTURE • Previous Articles     Next Articles

Adsorption Behavior and Mechanism of Grafted PMAA-HEMA/NVP Microspheres toward Lysozyme

FU Hong-Yan, GAO Bao-Jiao, NIU Qing-Yuan   

  1. Department of Chemical Engineering, North University of China, Taiyuan 030051, P. R. China
  • Received:2009-07-22 Revised:2009-11-05 Published:2010-01-26
  • Contact: GAO Bao-Jiao


The crosslinking copolymerization of 2-hydroxyethyl methacrylate (HEMA) and N-vinylpyrrolidone (NVP) was performed using the inverse suspension polymerization method resulting in crosslinked HEMA/NVP microspheres. Subsequently, the graft polymerization of methacrylic acid (MAA) was conducted using the“grafting from”method and the grafted PMAA-HEMA/NVP microspheres were obtained. The adsorption property and adsorption mechanism of the grafted microspheres were investigated in depth using lysozyme (LYZ) as a basic protein model. The zeta potential of the grafted microspheres was determined. Several factors that affected the adsorption property of the system such as the pH of the medium, the grafting degree of the microspheres and the ionic strength were examined. Experimental results indicate that in a wide pH range, the zeta potential of the grafted PMAA-HEMA/NVP microspheres has a large negative value. Therefore, a high density of negative charge is present on the surfaces of the grafted microspheres. The strong electrostatic interaction results in which the grafted PMAA-HEMA/NVP microspheres exhibit very strong adsorption ability toward lysozyme. The adsorption capacity of the grafted microspheres for lysozyme initially increases and then decreases as the pH increases and a maximumadsorption (90 mg·g-1) is found at pH=9, which is close to the isoelectric point of lysozyme. The ionic strength affects the adsorption property of the grafted microspheres greatly. As pH<9, the adsorption capacity of lysozyme decreases as the NaCl concentration increases, whereas as pH>9, the adsorption capacity of lysozyme increases as the NaCl concentration increases.

Key words: Polymethacrylic acid, Grafted polymeric microspheres, Basic protein, Lysozyme, Adsorption mechanism


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