Micromolded PDMS planar electrode allows patch clamp electrical recordings from cells

Abstract

The patch clamp method measures membrane currents at very high resolution when a high-resistance 'gigaseal' is established between the glass microelectrode and the cell membrane (Pflugers Arch. 391 (1981) 85; Neuron 8 (1992) 605). Here we describe the first use of the silicone elastomer, poly(dimethylsiloxane) (PDMS), for patch clamp electrodes. PDMS is an attractive material for patch clamp recordings. It has low dielectric loss and can be micromolded (Annu. Rev. Mat. Sci. 28 (1998) 153) into a shape that mimics the tip of the glass micropipette. Also, the surface chemistry of PDMS may be altered to mimic the hydrophilic nature of glass (J. Appl. Polym. Sci. 14 (1970) 2499; Annu. Rev. Mat. Sci. 28 (1998) 153), thereby allowing a high-resistance seal to a cell membrane. We present a planar electrode geometry consisting of a PDMS partition with a small aperture sealed between electrode and bath chambers. We demonstrate that a planar PDMS patch electrode, after oxidation of the elastomeric surface, permits patch clamp recording on Xenopus oocytes. Our results indicate the potential for high-throughput patch clamp recording with a planar array of PDMS electrodes. #

Mammalian electrophysiology on a microfluidic platform

“…Of cells tested here, 27% had a cellattached resistance of Ͼ250 M⍀ (average 301 M⍀), and gigaohm seals were obtained for 5% of cells. Whereas hydrophilic glass-like surfaces were previously believed to be a requirement for gigaseal formation (6,13,23), these data demonstrate the possibility of gigaseal formation on hydrophobic elastomer surfaces. Even for more modest sealing resistances (Ͼ100 M⍀), we were able to obtain whole-cell configuration and accurately record whole-cell currents down to 20 pA.…”

“…PDMS substrates were first used successfully to perform whole-cell recording of Xenopus oocytes by micromolding of an orifice in a planar substrate (6). Modification of the planar design by air molding facilitates mammalian cell recording (13), but with several distinct disadvantages.…”

“…These experiments are important, but the planar geometry has several limitations. For oocyte electrophysiology, the planar pores are arrayed with a distance of Ϸ1 mm between patch sites, requiring additional fabrication, alignment, and bonding steps to obtain a working device with integrated microfluidics (6). For mammalian electrophysiology, an optically opaque cell suspension is needed (13), negating the benefits of PDMS translucency.…”

“…For mammalian electrophysiology, an optically opaque cell suspension is needed (13), negating the benefits of PDMS translucency. And for all cell types, plasma treatment is used to obtain a hydrophilic PDMS surface for improved sealing, but the effects are temporary, requiring all planar devices to be used within hours of fabrication (6,13).…”

Advances in patch clamp technique: towards higher quality and quantity

“…However, commercial exploitation of the automated patch clamp was particularly achieved by use of the planar patch clamp. This technology was originally developed already in 1970s (Kostyuk et al 1975) but for the ultra-low-noise patch clamp recordings adapted in late 1990s by Klemic et al (2002). In the planar patch clamp, the microelectrode is replaced by a glass multi-well plate (the so-called patch plate or seal chip) with 1-2 µm microscopic recording aperture placed in the middle of the bottom of every well (for figure see Clare 2010).…”