Research Of Preparition Biological Polysaccharide Functionalized Carbon Nanotubes And Application For Enzyme Immobilization

A novel amino-cyclodextrin was synthesized, and it was covalentlyattached to multiwalled carbon nanotubes (MWNTs). The functionalizedMWNTs (f-MWNTs) have very good aqueous dispersibility. Bovine serumalbumin (BSA) was adsorbed onto f-MWNTs through noncovalent interactions,including the hydrophobic interaction of the residues of BSA with the wall ofMWNT and the guest-host interaction of the residues with the cyclodextrin (CD)moieties of f-MWNTs. The Ultraviolet–visible (UV-vis) absorption of thef-MWNT-BSA hybrid was measured with UV-vis spectrometer; the absorbancecan be described well with the Beer Lambert law. The X-ray diffraction patternshave indicated that the crystalline form of BSA has been changed after theadsorption of BSA on f-MWNTs. The circular dichroism spectra have shownthat a high percentage of-helical content can be retained for BSA adsorbed on f-MWNTs. The results also indicate that the change of secondary structure ofBSA is mainly due to the hydrophobic interaction of the residues of BSA withthe wall of f-MWNT, while the secondary structure is much less affected by theinteraction of the CD moieties with BSA.Phase transfer of multi-walled carbon nanotubes (MWNTs) from anaqueous phase into an organic phase is achieved. The transfer utilizes thehydrogen-bonding interactions between the disaccharide group of a sugar-basedamphiphile and oxygenated functional groups on the surface of MWNTs. Thedispersion of carbon nanotubes in a wide range of organic solvents is enabled,which represents the first example of solubilization of carbon nanotubes inorganic solvents via hydrogen bonding interactions.The immobilized lipase was utilized for the resolution of the modelcompound (R, S)-1-Phenyl ethanol in heptane, the ionic liquid [Bmim]PF6aswell as the heptane/[Bmim]PF6mixture. In the reaction media, the enzymaticactivity by the immobilized lipase is much higher than that by the free lipase. Incomparison to the catalysis in the ionic liquid and heptane, when using themixture of heptane/[Bmim]PF6as the reaction medium, the catalysis by theimmobilized lipase at the heptane-ionic liquid interface exhibited a highercatalysis activity. This is due to two aspects: the continuous diffusion ofsubstrate from the heptane phase to the ionic liquid phase; the simultaneousextraction of product from the ionic liquid phase. In addition, the interfacial enzymatic catalysis facilitates the reuse of the immobilized lipase and the ionicliquid.