Enantioselective hydrolysis of racemic esters using pig liver esterase

Characterization of an anion-exchange porous polypropylene hollow fiber membrane for immobilization of ABL lipase

Hollow fiber membrane offers the advantage to integrate catalytic conversion, product separation and catalyst recovery into a single separation process compared to conventional systems. Polypropylene (PP) hollow fiber membrane is a chemically inert and stable membrane with high potential for enzyme immobilization. The surface properties of polypropylene have been modified by radiation induced graft polymerization. Samples were prepared by grafting of glycidylmethacrylate (GMA) using gamma radiation, at different monomer concentrations and irradiation dose. The resulting epoxy was converted into a diethylamino group as an anion-exchange medium to bind the lipase molecules. Surface properties of the grafted and amine treated samples were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM) and contact angle measurements. AFM revealed higher surface roughness for grafted samples than that of virgin polymer. SEM micrographs illustrated that the porous network was retained at high degree of grafting. Contact angle measurements showed excellent wetting properties with water for the grafted and amine treated membranes. Thermal properties were studied using differential scanning calorimeter (DSC) and thermogravimetic analysis (TGA). It was observed that grafting occurred mainly in the amorphous region of the membranes. Activity and operational stability of ABL lipase, isolated from Arthobacter sp. were assayed after immobilizing it to the modified PP hollow fiber. Immobilized lipase retained 20U/g activity after ten hydrolysis cycles and 68% residual activity after 12 weeks of storage.

Immobilized microfluidic enzymatic reactors

The use of enzymes for cleavage, synthesis or chemical modification represents one of the most common processes used in biochemical and molecular biology laboratories. The continuing progress in medical research, genomics, proteomics, and related emerging biotechnology fields leads to exponential growth of the applications of enzymes and the development of modified or new enzymes with specific activities. Concurrently, new technologies are being developed to improve reaction rates and specificity or perform the reaction in a specific environment. Besides large-scale industrial applications, where typically a large processing capacity is required, there are other, much lower-scale applications, benefiting form the new developments in enzymology. One such technology is microfluidics with the potential to revolutionize analytical instrumentation for the analyses of very small sample amounts, single cells or even subcellular assemblies. This article aims at reviewing the current status of the development of the immobilized microfluidic enzymatic reactors (IMERs) technology.