Process for examining membrane enclosed biocompartments

#This application claims priority to German Application No. 100 28692.5 filed Jun. 9, 2000.

#The invention concerns a process for examining of membrane enclosed biocompartments, wherein the biocompartments are arranged in amicro-flow chamber. This micro-flow chamber is subject to the through-flow of a culture medium containing an active agent and which is in contact with the said biocompartments and possibly has an effect thereon. Further, the pH value of the culture medium present in the micro-flow chamber can be measured. In this arrangement, the biocompartments can hold, for instance, biological cells, microorganisms (fungi, bacteria), biochemical compartments and/or mitochondria.

#EP 0 394 406 B1 discloses a process of the type known in the art, in which living, biological cells are placed in a micro-flow chamber being subjected to the through-flow of a culture medium and which chamber has a silicon sensor on its bottom. A reference electrode is provided in the micro-flow chamber, which is in continual contact with the culture medium. In the case of this previously known process, in a first process step, the through-flow of the culture medium is stopped in the micro-flow chamber. Under these circumstances, the pH value, serving as a metabolic indicator of substance change in the culture medium residing in the micro-flow chamber, is determined by measurement of the electrical potential between the silicon-sensor and a reference electrode. With this process, it is possible to measure, for instance, the action of a cell-affecting agent on the metabolism of the cells. A detriment, however, lies in the fact, that the process enables only one determination in regard to a yield of acid metabolic products, while other changes caused by the metabolism of the cells are not given consideration.

#What follows is a detailed description of preferred embodiments of the invention, which described are in more detail with the aid of the drawings. Shown in a schematic manner are:

#FIG. 1 is a longitudinal section through an apparatus with a micro-flow chamber for the examination of living, membrane enclosed, biocompartments,

#FIG. 2 is a longitudinal section through an ISFET inserted in the base of the micro-flow chamber with an electrode placed proximal to said ISFET, whereby, on the ISFET and on the electrode, biological cells are adherently placed,

#In a process for the examining of membrane enclosed biocompartments, biocompartments 1 were designed as biological cells placed in amicro-flow chamber 2. The micro-flow chamber 2 possesses a measurement space 3, enclosed by a chamber housing. The space 3 is provided with an inlet opening 4 and an exit opening 5 for nutrient or culture medium. The chamber housing has a chamber base part 6 and a top part 7 which fits said base part 6 and the two parts are sealed liquid tight to one another by an interposed sealing ring 8.

#The inlet opening 4 of the measurement space is connected to the measuring space 3 by a feed conduit 9, which in turn is connected to a culture medium supply 10. A pump 11 is placed in the feed canal 9 for the transport of the culture medium. The pump 11 can be turned on and off by means of a control apparatus (not shown). The exit opening 5 of the micro-flow chamber 2, is joined by means of a connecting line 12, to an exhaust opening 13 for release of the culture medium. In the measuring space 3, the biocompartments 1 stand in contact with the culture medium.

#In the base of the measuring space 3, are placed a plurality of ISFET's 14. As shown in FIG. 2, the ISFET's possess a substrate 15 comprised of semiconductor material, in which are placed highly doped zones with conducting lines printed remote from substrate 15 to connect the electronic drain 16 and source 17. Between drain 16 and source 17, is a gate 18. Gate 18, drain 16 and source 17 are electrically insulated from the measurement space 3 by means of a silicon nitride layer (not shown). The silicon nitride layer forms on its side remote from the gate 18, an active sensor layer. By means of which layer, the ISFET 14 is controllable through the hydrogen ions present in the culture medium. Gate 18, drain 16 and source 17 of the ISFET are connected with a known evaluation apparatus for the determination of the pH value of the culture medium which is somewhat proportional to measurement signal of the respective ISFET 14.