Development of an enzymatic microreactor based on microencapsulated laccasewith off-line capillary electrophoresis for measurement of oxidation reactions

摘要

Microencapsulation is used here as a new technique to immobilize enzymes in a microreactor coupledoff-line to capillary electrophoresis (CE), allowing the determination of enzymatic reaction prod-ucts. The redox enzyme laccase was encapsulated using the method of interfacial cross-linking ofpoly(ethyleneimine) (PEI). The 50 μm diameter capsules were slurry packed from a suspension into acapillary-sized reactor made easily and quickly from a short length of 530 p.m diameter fused-silicatubing. The volume of the bed of laccase microcapsules in the microreactor was in the order of 1.1through which 504 of the substrate o-phenylenediamine (OPD) was flowed. The oxidation product 2,3-diaminophenazine (DAP) and the remaining OPD were quantified by CE in a pH 2.5 phosphate buffer.Peak migration time reproducibility was in the order of 0.4% RSD and peak area reproducibility was lessthan 1.7% RSD within the same day. Using the OPD peak area calibration curve, a conversion efficiency of48% was achieved for a 2-min oxidation reaction in the microreactor.