Well-Defined Microapertures for Ion Channel Biosensors

Abstract

Gated ion channels are excitable nanopores in biological membranes. They sense and respond to different triggers in nature. The sensory characteristics of these channels can be modified by protein engineering tools and the channels can be functionally reconstituted into synthetic lipid bilayer membranes. The combination of the advances in protein engineering with electrical and/or optical signal detection possibilities makes ion channels perfect detection modules for sensory devices. However, their integration into analytical devices is problematic due to the instability of lipid bilayers. Here, we report on developing a stable sensory chip containing a mechanosensitive channel in a Si/SiO(2) chip with a 3 μm pore. Our new fabrication strategy was straightforward. It required only lithography and dry etching for the pore definition and membrane release and reduced the risk of membrane rupture in the fabrication process. A gated ion channel could be inserted, with the retention of its function, into the pores of Si/SiO(2) chips and be detectable at the single channel level upon activation. Excitable ion channels in stable small pores can serve as very sensitive detectors of specific molecules.