Polymers and Pigments Department, National Research Center, Dokki, Giza, Egypt.
Carbohydr Polym. 2013 Feb 15;92(2):2095-102. doi: 10.1016/j.carbpol.2012.11.084. Epub 2012 Dec 5.
Chitosan grafted with polymethyl methacrylate (PMMA-g-CS) was prepared via a free-radicals polymerization technique as a carrier for enzyme immobilization. α-Chymotrypsin (CT), as an enzyme model in this study, was immobilized onto the prepared PMMA-g-CS via covalent bonding. Calcium alginate (CA) beads were developed for encapsulating PMMA-g-CS-CT to produce PMMA-g-CS-CT/CA composite beads. Morphology and size of PMMA-g-CS particles were investigated by TEM and found to be in the nanoscale. The structure and surface morphology of the beads before and after immobilization process were characterized by FT-IR and SEM, respectively. Both the bound CT content and relative activity of immobilized enzyme were measured. A higher retained activity (about 97.7%) obtained for the immobilized CT at pH 9 for 24 h. The results indicated that immobilized CT maintained excellent performance even after 25 reuses and retained 75% from its original activity after 60 days of storage at 25 °C.
壳聚糖接枝聚甲基丙烯酸甲酯（PMMA-g-CS）通过自由基聚合技术制备，作为酶固定化的载体。α-糜蛋白酶（CT）作为本研究中的酶模型，通过共价键固定在制备的 PMMA-g-CS 上。海藻酸钠（CA）珠被开发用于包埋 PMMA-g-CS-CT，以产生 PMMA-g-CS-CT/CA 复合珠。通过 TEM 研究了 PMMA-g-CS 颗粒的形态和尺寸，发现其处于纳米级。通过 FT-IR 和 SEM 分别对固定化前后珠的结构和表面形貌进行了表征。测量了结合 CT 的含量和固定化酶的相对活性。在 pH 9 下固定化 CT 24 h 后，获得了更高的保留活性（约 97.7%）。结果表明，即使经过 25 次重复使用，固定化 CT 仍保持优异的性能，在 25°C 下储存 60 天后，其活性仍保留了原始活性的 75%。
