MINIATURIZED THIN-FILM GLUTAMATE AND GLUTAMINE BIOSENSORS

Integrated thin film biosensors were developed for the simultaneous me asurement of L-glutamine and L-glutamate in a mu-flow cell. Due to a n ovel glutaminase with an activity optimum in the neutral pH range, dir ect monitoring of glutamine in a mammalian cell culture medium could b e performed. The glutamine bienzyme sensor was prepared by co-immobili zation of glutaminase with glutamate oxidase within a photopatterned p oly(2-hydroxyethyl methacrylate) (pHEMA) hydrogel membrane. The sensor response was linear in the concentration range of 50 mu mol to 10 mmo l glutamine/l. Additionally, a glutamate biosensor was integrated on t he sensor chip for difference measurement of possible glutamate interf erences. The sensor-chip could be used for at least 300 measurements w ithout any alteration in the performance of its sensors. A new sensor- chip with an integrated how cell provided the possibility of simultane ous measurement of four different parameters at a cell volume of 1 mu l. In order to complete the microsystem, and in order to obtain a ''la b on chip'', a battery operated surface mounted device (SMD) potentios tat was developed.