Capillary electrophoresis-based immobilized enzyme reactor using particle-packing technique.

A novel method using particle-packing technique to fabricate capillary electrophoresis (CE)-based immobilized enzyme reactor (IMER) was accomplished by utilizing perfusive silica single particles as the frits and large-pore beads as the enzyme supports. The fabrication procedure is rapid and simple; the length and enzyme loading amount of the CE-IMERs could be easily adjusted. Performance and feasibility of the CE-IMERs were investigated using on-line trypsin digestion as the model enzyme reaction. High reproducible on-line enzyme assay was demonstrated with RSD less than 4.1% and 3.8% for peak area and migration time of the substrate and product over 100 consecutive runs, respectively. The enzyme can still maintain the activity for at least 10 days, indicating remarkably stability of the CE-IMERs. The CE-IMERs were successfully applied for accurate analysis of trypsin inhibition as well as on-line digestion of standard proteins (myoglobin and BSA). The present method provides a new interesting alternative to open-tubular and monolithic CE-IMERs, thus expands the application of the CE technique for on-line enzyme assay and analysis and characterization of peptides and proteins.