Micro Analysis System for Digestive Enzymes Based on Integrated Automatic pH-Stats

Aiming for the application to an ingestible micro system, a microanalysis system for the determination of the activity of digestive enzymes was realized. The analysis was conducted by using an on-chip micro-pH-stat which worked on the basis of an irregular use of the electrochemical three-electrode system. The operation using a potentiostat caused a negative feedback, maintaining the solution pH at a constant value. The system used a freeze-dried enzyme substrate. The very porous matrix facilitated rapid dissolution and mixing with the enzyme solution. The determination of the activity of pepsin and trypsin was conducted at the optimum pHs for the respective enzymes by measuring the generated charge accompanying the hydrolysis of hemoglobin. In both cases, a distinct increase in the generated charge was observed as the enzymatic reaction proceeded. Linear relationships were observed between the initial rate of charge increase and the activity of the enzymes.