A Cell-Culture-Type Planar Ion Channel Biosensor

Abstract

We have developed a new planar-type ion channel biosensor with a silicon-on insulator substrate and a cell culture function. Fibronectin is coated on the substrate surface to promote cell growth in this sensor. A transient receptor potential vanilloid type 1 (TRPVl) channel-expressing HEK293 cell is positioned on the micropore of the SOI sensor chip and incubated. Although the seal resistance was quite small, 10-20 MQ, compared with that of the conventional pipette patch-clamp method, the signal-to-noise level was sufficiently high. However, a much lower noise level is required for observing the opening and closing of fewer than 30 channels.

Improvements in the performance of an incubation-type planar patch clamp biosensor using a salt bridge electrode and a plastic (PMMA) substrate

“…The Si sensor chip fabrication process,involving the preparation of a Si-on-insulator (SOI) substrate, was reported previously [16,17]. A thermal oxidation layer about 1 min thickness was formed on the substrate surface by wet thermal oxidation at 900C using a water-saturated O 2 flow.…”

“…The surfaces of both the Si and PMMA sensor chips were coated with poly-L-lysineECM (PLL, Sigma-Aldrich Co.), which performed better in the preliminary biosensor culture experiments than the fibronectin ECM used previously [16,17].The 50 μL solution was dropped onto the substrate surface, followed by incubation for 1-2 days at room temperature. At this stage, the surface densities of the ECM were about 3-5 μg/cm 2 .…”

“…The electrical measurement systems used here were the same as those described in our previous planar patch clamp experiments [16,17]. The noise properties of the present biosensor were measured inside a shield box.…”

“…Such a technique would be especially useful in applications to in vitro neural network studiesinvolving dissociated cultured neurons [12][13][14][15]. We previously developed an incubation-type planar patch clamp device and demonstrated its operation using the transient receptor potential cation channel subfamily V1 (TRPV1)-expressing HEK293 cells with capsaicin as a ligand molecule [16,17]. Several outstanding technical challenges, however, remain in the current incubation-type planar patch clamp biosensors.…”

Noise Properties of Incubation-Type Planar Ion Channel Biosensor

“…To solve these problems of the conventional pipette and planar patch-clamp methods, we have recently proposed and fabricated a new planar-type ion channel biosensor capable of cell incubation inside the device. 5,6) Noise properties are the most important issues in ion channel biosensors, and they have been investigated in detail in pipette patch-clamp and black membrane biosensors, in which high seal resistance (>G) exists between the membrane and the pipette. 7,8) The noise properties of planartype ion channel biosensors, where seal resistance is relatively low, however, to the best of our knowledge have never been investigated, despite on their significance.…”