PS胶体粒子表面逐层自组装固定化SOD及其生物活性

通过逐层自组装技术成功地把超氧化物歧化酶(SOD)吸附在聚苯乙烯(PS)胶体粒子表面.zeta电位和TEM证明了聚阳离子或聚阴离子型SOD与相反电荷的聚电解质在PS胶体粒子表面的交替吸附.通过测定SOD被胶体粒子吸附后上清液的生物活性,得到聚阴离子型SOD(pH=8.0)和聚阳离子型SOD(pH=4.3)在PS胶体粒子表面的吸附量分别为12和51IU,相对活性分别为23.4%和2.9%.聚阴离子型SOD在PS胶体粒子表面能形成平滑规整的膜,导致较高的相对活性.研究结果表明,通过调节pH值,可以优化自组装固定化酶的聚集状态和生物活性

Immobilization of Superoxide Dismutase by Layer-by-layer Assembly on Surface of PS Colloid Particles and Their Bioactivity

Novel enzyme multilayer films on the surface of polystyrene(PS) colloid particles was fabricated by layer-by-layer(LbL) self-assembly. Superoxide dismutase(SOD) was adsorbed on the PS particles as either polycation or polyanion switched by adjusting pH alternatingly with the oppositely charged polyelectrolytes. zeta-Potential and TEM results indicated the regular and stepwise growth of the multilayer structure. The amount of the immobilized SOD was estimated from the difference in SOD bioactivity of the supernatant after adsorption and SOD solution before adsorption by using the pyrogallol oxidation method. The immobilization amount of SOD was 12 and 51 IU when adsorbed in pH=8.0 as a polyanion and in pH=4.3 as a polycation, respectively. However, the relative activity of the former was 23.4% while that of the latter was 2.9%, compared to that of free SOD in aqueous solution. Anionic SOD was found to form more regular and smooth layers on the PS particle surface and cationic SOD to aggregate. By adjusting pH of the adsorption solution we can optimize the assembled status and bioactivity of particle-immobilized enzyme.