title: Hollow cross-linked enzyme aggregates (h-CLEA) of laccase with high uniformity and activity.
abstract: Hollow cross-linked enzyme aggregates of laccase (h-CLEA laccase) can be prepared by employing a millifluidic reactor carrying two coaxial laminar flows. In a confluence zone where acetonitrile and an aqueous solution of laccase meet, diffusion of acetonitrile into the aqueous solution gives rise to rapid precipitation of laccase aggregates at the water/acetonitrile interface, as is evidenced by fluorescence images. By controlling the flow rates carefully in the laminar flow regions, h-CLEA laccase around 220±10nm can be obtained, and the size of the h-CLEA laccase increases with increasing flow rates of both solutions. The h-CLEA laccase particles are distinctly different from CLEA laccase prepared in batch processes. The former only consist a crust of cross-linked enzymes (with a hollow core) whereas the latter has a highly porous structure. When the h-CLEA laccase is used as biocatalysts, their activity (0.26U/mg) is comparable to that of free enzymes at neutral pH due to the hollow structure. Moreover, the activity of h-CLEA laccase is higher than that of free laccase at high pH. For example, trypan blue (a dye molecule) can be decolorized completely in the presence of h-CLEA laccase within 270min even at pH 10.0, at which the free enzyme completely loses its activity. Because of their uniform sizes, h-CLEA laccase can be trapped in a membrane for continuous degradation of trypan blue up to 96h without losing any activity. This study shows the superiority of h-CLEA laccase compared to other types of immobilized enzymes.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576, Singapore.
authors.forename: Le Truc
authors.initials: LT
authors.lastname: Nguyen
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576, Singapore.
authors.forename: Nianjia
authors.initials: N
authors.lastname: Seow
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576, Singapore. Electronic address: cheyk@nus.edu.sg.
authors.forename: Kun-Lin
authors.initials: KL
authors.lastname: Yang
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D002384:Catalysis; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004058:Diffusion; D004800:Enzymes, Immobilized / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D042845:Laccase / Q000737:chemistry*; D044085:Microfluidics; D008856:Microscopy, Fluorescence; D011138:Polytetrafluoroethylene / Q000737:chemistry; D013696:Temperature; D014343:Trypan Blue / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D014867:Water; D011138:Polytetrafluoroethylene; D042845:Laccase; D014343:Trypan Blue; C032159:acetonitrile
keywords: CLEA; Hollow particles; Laccase; Laminar flow; Millifluidics