Immobilization of Lipase Onto Dopamine Functionalized Magnetic Nanoparticles

A nanocarrier Fe₃O₄ @ OA @ DA, with the structure of a dopamine functionalized Fe₃O₄ nanoparticles coated with oleic acid (OA), was simply prepared by dipping the Fe₃O₄ @ OA magnetic nanoparticles in dopamine solution. Lipase from Thermomyces lanuginosus was immobilized onto the obtained nanocarrier via covalent coupling. A high immobilization efficiency of 88%, and an immobilization yield of 97% with enzyme loading of 13.09 mg/g-support were achieved under the optimal conditions: immobilization time 10 h, pH 7.0, and enzyme concentration 0.27 mg/mL. Compared with the free enzyme, thermostability of the immobilized lipase was 2.9-fold improved at 60 °C. More than 75% initial activity of the immobilized lipase was remained after ten repeated uses. The V _max and K_m of the free and immobilized lipase were determined as 2.51 mmol/min, 2.13 mmol/min and 8.86 mM, 10.50 mM, respectively. These results indicated that the prepared magnetic oleic acid nanoparticle with dopamine functionalization is a good carrier for lipase immobilization, and has the potential uses for immobilization of other enzymes.