Silicon-on-insulator based nanopore cavity arrays for lipid membrane investigation

Abstract

We present the fabrication and characterization of nanopore microcavities for the investigation of transport processes in suspended lipid membranes. The cavities are situated below the surface of silicon-on-insulator (SOI) substrates. Single cavities and large area arrays were prepared using high resolution electron-beam lithography in combination with reactive ion etching (RIE) and wet chemical sacrificial underetching. The locally separated compartments have a circular shape and allow the enclosure of picoliter volume aqueous solutions. They are sealed at their top by a 250 nm thin Si membrane featuring pores with diameters from 2 µm down to 220 nm. The Si surface exhibits excellent smoothness and homogeneity as verified by AFM analysis. As biophysical test system we deposited lipid membranes by vesicle fusion, and demonstrated their fluid-like properties by fluorescence recovery after photobleaching. As clearly indicated by AFM measurements in aqueous buffer solution, intact lipid membranes successfully spanned the pores. The nanopore cavity arrays have potential applications in diagnostics and pharmaceutical research on transmembrane proteins.

Fabrication of Solid State Nanopore in Thin Silicon Membrane Using Low Cost Multistep Chemical Etching

“…Recent advancements in nanofabrication techniques allow artificial solid-state nanopores to be fabricated in Si 3 N 4 , SiO 2 , Si, and alumina [2,6,12,13,14,15,16,17,18,19,20,21,22,23,24,25]. These nanopore devices uncover many advantages, such as the ability to control a pore diameter, increased mechanical strength, and integration with micro/nano-devices.…”

“…The use of single solid-state nanopores (SSSN) facilitates the monitoring and characterization of biomolecule species such as RNA, DNA, polypeptides, and other macromolecules at single molecular precision [2]. These advantages result increased stability of fused lipid membranes over a larger range of conditions such as ionic concentration, pH, and temperature and solid-state nanopore technology are currently being used to improve the detection of ion transport through protein channels [2,6,18,19,23,25]. …”

Multiplexed Parallel Single Transport Recordings on Nanopore Arrays

“…Previous approaches used giant unilamellar vesicles (GUVs, typically 10-100 µm in diameter) for this purpose, as the vesicle diameter has to exceed the pore size to allow the formation of a SLB. 27 However, it is of great advantage to prepare the SLB from large unilamellar vesicles (LUVs, ∼400 nm in diameter) instead. In contrast to GUVs, LUVs are easily formed in physiological conditions and can be used for the reconstitution of membrane proteins without the loss of their native structure and function by dehydration.…”

Controlled sealing of nanopores using an easily fabricated silicon platform combining in situ optical and electrical monitoring

“…The silicon chips were fabricated using a method derived from previous works [10,11] Germany) using conventional ebeam lithography and reactive ion etching. The buried oxide (BOX) below the nanopore line was then etched through the nanopores by a 50% vol/vol hydrofluoric acid solution during 1 min and 30 s. Consequently, a buried channel, linking all the nanopores together under the top silicon membrane was created.…”