A Scanning Force Microscope for Simultaneous Force and Patch-Clamp Measurements on Living Cell Tissues

The construction of a novel type of experimental setup is described where a scanning force microscope (SFM) is combined with an upright infrared differential interference contrast (DIC) video microscope and with a conventional patch-clamp setup. The deflection of the SFM cantilever is detected with the so-called optical deflection method through the objective of the optical microscope. With this combined setup, subcellular structures can be identified on living cells with the video microscope and simultaneously investigated with the SFM and the patch-clamp pipette. By means of a two-axis translation stage the specimen chamber is moved laterally with a resolution of better than 2 um. Thus the instrument enables an easy approach of the SFM tip to any optically identified cell structure. The features of the instrument are demonstrated with preparations of cultivated neuronal cells. Simultaneous measurements of ion-current and force in organotypic cultures of mechanosensitive hair cells of the inner ear are proposed, as investigations of cell tissue preparations of up to 400 um thickness are possible with this instrument.