Poly(carboxybetaine methacrylate)-functionalized magnetic composite particles: A biofriendly support for lipase immobilization.

In this work, poly(carboxybetaine methacrylate) as an extremely hydrophilic polymer was modified on superparamagnetic Fe3O4 nanoparticles (pCB-Fe3O4), which were employed to immobilize porcine pancreatic lipase. The properties of immobilized lipase were investigated in comparison with the free enzyme counterpart. Enzymatic stability, reusability, and activity of the immobilized lipase were found significantly superior to that of the free lipase. In particular, at an elevated temperature of 60°C, the immobilized lipase retained 50% of its initial activity after 150min, while the free enzyme displayed only one-third activity of the immobilized enzyme. Besides, the immobilized lipase retained >60% of its initial activity after 7 cycles. Furthermore, the value of Kcat/Km indicated the catalytic efficiency of the immobilized lipase was increased by 50% compared to that of the free one. The pCB-Fe3O4 particles displayed non-cytotoxicity, while the naked Fe3O4 particles caused only 50% viability of NIH 3T3 cells. These results showed that pCB-Fe3O4 composite particles had higher efficiency and improved stability for lipase immobilization, which are more promising for industrial scale up of biocatalytic systems with excellent biocompatibility.