We report on the direct electrical interfacing of a recombinant ion channel to a field-effect transistor on a silicon chip. The ion current through activated maxi-K_Ca channels in HEK293 cells gave rise to an extracellular voltage between cell and chip which controlled the electronic source-drain current. A comparison with patch-clamp recording showed that the channels at the cell-chip interface were fully functional and that they were significantly accumulated there. The direct coupling of potassium channels to a semiconductor on the level of an individual cell is the prototype for iono-electronic interfacing of ligand gated or G-protein coupled ion channels and for the development of screening biosensors with many transfected cells on a chip with a large array of transistors.
Transistor records of maxi-KCa channels. Holding voltage V_M = -100 mV, depolarizing voltage pulses (300 ms) of V_M = -68, -23, 30, 40, 45, 53, 58 mV from bottom to top. Bandwidth 1 kHz. Left column: transistor records scaled by the equivalent voltage V_J on the open gate. Right column: whole cell patch-clamp current I_M.
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