Microfluidic system for the determination of the activities of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase

A microfludic system for the analysis of glutamic oxaloacetic transaminase (GOT) or glutamic pyruvic transaminase (GPT) activity was developed. The system consisted of a glass substrate with a micro amperometric L-glutamate sensor and a polydimethylsiloxane (PDMS) substrate with a Y-shaped flow channel. A sample solution containing either of the enzymes and a solution containing the substrates for the enzymes were introduced from two injection ports. When the flows were stopped, the two solutions mixed immediately within seconds by diffusion. L-glutamate produced by the enzymatic reaction of GOT or GPT was detected by using the amperometic L-glutamate sensor. Current increase was observed immediately after mixing and the initial slope of the response curve depended linearly on the activity of GOT or GPT. The response was enhanced as the volume of the mixing channel increased. The influence of interferents was negligible, because the activity was determined by the rate of the current increase.