Assay of Analytes after Enzymatic Reactions

FIGURE 10.20 Schematic representation of the microfluidic device used for the two-step enzymatic detection of glucose [1043]. Reprinted with permission from the American Chemical Society. 

FIGURE 10.21 (a) Cross-sectional view of the microchip, heating element, and the thermocouples. (b) Schematic of the microchip used for on-chip reactions, separations, and post-column labeling. The fluid reservoirs are (1) substrate, (2) enzyme or DTT, (3) buffer, (4) sample waste, (5) NDA, and (6) waste [1058]. Reprinted with permission from Elsevier Science. 

FIGURE 10.22 Electropherograms of the products following on-chip tryptic digestion of bovine insulin B-chain at 37°C. The flow in the reaction channel was stopped for different times to study the effect on the reaction. Control runs (see the flat curves) without insulin B-chain were performed in the continuous flow mode and in a flow with a stop time of 6 min. The arrows indicate the migration time of benzylamine, which was added as an EOF marker. All electropherograms are plotted on the same scale with an offset for clarity [1058]. Reprinted with permission from Elsevier Science. 

Enzymatic conversion of NBD-labeled ArgOEt to NBD-Arg was monitored in a PMMA microchannel. The enzyme, trypsin, was immobilized via the reactive ester groups on a phospholipid polymer adsorbed on the PMMA surface [ 1059]. 

It was found that cytochrome c, (J-casein, and BS A can be digested by trypsin-immobilized beads in a microchamber on a glass chip. The protein (1 mg/mL) was mobilized by EOF. Although without external heating, Joule heating may assist in the enzymatic digestion reaction of the proteins [116]. 

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