writer：Panpan Zhao, Lei Tian, Xue Li, Zafar Ali, Baoliang Zhang, Hepeng Zhang, and Qiuyu Zhang
keywords：Flexible chains; Generations; Lipase immobilization; Magnetic nanocarriers; PAMAM dendrimers
source：期刊
specific source：http://pubs.acs.org/doi/abs/10.1021/acssuschemeng.6b00967
Issue time：2017年

Polyamidoamine (PAMAM) dendrimers have been widely applied in biomacromolecule immobilization, catalysis carriers, gene therapy, and drug delivery. However, there is still a lack of systematic research about lipase and protein immobilized by PAMAM dendrimers. Herein, we used three types of amine reagents to graft dendritic macromolecules on Fe3O4 nanoparticles and obtained a variety of Fe3O4@SiO2/PAMAM magnetic nanocarriers with different generations. The density of surface functional groups, the structure, and the length (generation) of the flexible chain play an important role in immobilizing Candida rugosa lipase (CRL). As a result, hexamethylenediamine (HMD) grafted dendritic magnetic carriers with the fourth generation (Gc-4) exhibited a superior performance in terms of immobilizing CRL. Then, polyethylenimine (PEI) instead of HMD was grafted to the Gc-4 to obtain a higher activity with respect to immobilized CRL (955.53 U/g) and free lipase. Furthermore, the immobilized CRL improved its tolerability performance in wider ranges of pH and temperature.