Influencing factors on the synthesis of magnetically responsive lipases

Magnetic Fe3O4 nanoparticles decorated with native carboxyl groups (Fe3O4-COOH) were prepared and used as magnetic carriers. These carriers were different from traditional solid supports, because they were free-standing and no aggregation in solution. Lipases were covalently bonded to these Fe3O4 nanoparticles through 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (Sulfo-NHS) activated coupling to synthesize magnetically responsive lipases( MRLs). The analyses of transmission electron microscope (TEM) showed no significant change on the size and shape of Fe3O4 nanoparticles after being conjugated with lipases. The conjugation of Fe3O4 nanoparticles and lipases was confirmed by electrophoresis and zeta potential analyses. Furthermore, the factors that affected the enzyme activity and specific activity of the MRLs were discussed. The optimized conjugation conditions were found to be that the dosages of the lipase solution and the EDC solution were 200 mu L and 10 mu L for 1 mL Fe3O4 respectively, the molar ratio of EDC and Sulfo-NHS was 1:2.5, and the conjugation time was 2 h. The prepared MRLs exhibited higher thermal stability and reusability. (C) 2014 Elsevier B.V. All rights reserved.