Substrate and a method for determining and/or monitoring electrophysiological properties of ion channels

A method of establishing a whole cell measuring configuration for determining and/or monitoring an electrophysiological property of one or more ion channels of one or more ion channel-containing structures, said method comprising the steps of:

• providing an assembly comprising:
• a first surface part and an opposite second surface, said substrate having a plurality of sites in the first surface part of the substrate, each of which is adapted to hold an ion channel-containing structure and each of which has a passage therein through the substrate connecting the first surface part and the second surface part, which passage has walls and is dimensioned to hold an ion channel-containing structure and to form a high resistance seal between said ion channel-containing structure and said substrate, around or along the walls of said passage, a plurality of measuring electrodes, each of which is associated with a respective site, and one or more reference electrodes;
• supplying a carrier liquid at one or more sites using a plurality of flow channel structures created in the substrate, said carrier liquid containing one or more ion channel-containing structures the carrier liquid contacting the first surface part of the substrate;
• positioning at least one of the ion channel-containing structures at a corresponding number of sites;
• forming a high electrical resistance seal between an area of contact of the outer surface of an ion channel-containing structure held at the site and a first surface part of the substrate around or along the walls of said passage, the seal, when established, separating a domain defined on one side of the seal established by the ion channel-containing structure and in electrolytic contact with the measuring electrode from a domain defined on the opposite side of the seal established by the ion channel-containing structure and in electrolytic contact with the respective reference electrode;
• checking for a high electrical resistance seal between an ion channel-containing structure held at a site and the first surface part of the substrate or along the walls of said passage with which the high electrical resistance seal is to be established by successively applying a first electric potential difference between the measuring electrode associated with the site and a reference electrode, monitoring a first current flowing between said measuring electrode and said reference electrode, and comparing said first current to a predetermined threshold current and, if the first current is at most the predetermined threshold current, then approving the site as having an acceptable seal between the ion channel-containing structure and the first surface part of the site;
• and
• establishing a whole-cell configuration at approved sites, whereby a third current flowing through ion channels of the ion channel-containing structure between the measuring electrode and the reference electrodes can be determined and/or monitored.