Lipase Immobilized On Functionalized Graphene Catalyzed Resolution Of Chiral Compound

Graphene, a novel one-atom-thick two-dimensional graphitic material, iscomposed of honeycomb arrangement of carbon atoms and its thickness isonly0.35nm, becomes the most thin material in the world. This material isfascinating in its exceptional electronic, thermal, and mechanical propertieswith the promise of a range of applications. Since discovered in the2004, thegraphene has attracted intense interest over the world, its finder Geim andNovoselov won the2010Nobel Prize for physics. In this paper,functionalizedgraphene has been characterized with the spectra of FTIR, XPS, XRD, AFMas well as TEM. The functionalized graphene was used to immobilize lipase,and the immobilized lipase has been applied to the enzymatic catalysis of theresolution of the (R,S)-(±)-1-Phenyl ethanol. It was found that theimmobilized lipase exhibited a much higher enzymatic activity that free lipase.The content is mainly focused on:1，The preparation of the functionalized graphene. Graphite oxide (GO)was synthesized from natural graphite by Staudenmaier’s method. Thegraphene sheets were prepared via thermal exfoliation of GO. This methodwill gets graphene much defective but high activity.We get the carboxyl ontothe graphene by making ultrasonic in the mixed acid. The functionalizedgraphene is characterized with the spectra of atomic force microscope (AFM)and image reveales the presence of sheets with1to2.2，Immobilized enzyme in the resolution of the chiral compound. In thispaper, lipase was covalently attached onto functionalized graphene by using NHS (N-hydroxysuccinimide) as activator and EDC HCL(N-ethyl-N-(3-(dimethylamino) propyl) carbodiimide hydrochloride) ascrossing agent in MES (2-(N-morpholino) ethanesulfonic acid) buffer andPBS (Phosphate buffer,50mM, pH=8.0). The functionalized graphenefacilitated enzyme loadings (0.2mg of lipase/mg functionalized graphene) asdetermined by BCA.Chiral compound (R,S)-1-Phenyl ethanol is used as template material toinvestigate the optimum conditions of resolution by the immobilized enzyme,including solvent, acyl donors and its molar ratio to chiral compound et al.High performance liquid chromatography analyses the interval samples withthe external standard method reach a conclusion that the optium concentrationof immobilized enzyme is10mg/ml, substrate is50mM, acyl donors is300mM, when temperature is50℃and reaction time is38h, the enantiomericexcess is99%and conversion of the substrate is50%.