August 11, 2009: Researchers at Lawrence Livermore National Laboratory have created a platform that uses lipid-coated nanowires to build prototype bionanoelectronic devices. The work shows promise for enhancing biosensing and diagnostics tools, neural prosthetics (e.g., cochlear implants), and even future computers.

Earlier research focused on integrating biological systems with microelectronics but came up short of achieving true seamless material-level integration. The LLNL team used lipid membranes, ubiquitous in biological cells, which “form a stable, self-healing, and virtually impenetrable barrier to ions and small molecules,” the researchers note in a statement. They can also house vast numbers of protein “machines” that perform various functions from recognition, transport, and signal transduction.

In their work, published online Aug. 10 by the Proceedings of the National Academy of Sciences, the team led by Aleksandr Noy incorporated lipid bilayer membranes into silicon nanowire transistors by covering the nanowire with a continuous lipid bilayer shell, which acted as a barrier. With the “shielded wire,” membrane pores were “the only pathway for the ions to reach the nanowire,” Noy said, enabling the nanowire device “to monitor specific transport and also to control the membrane protein.” The membrane pore could be opened and closed by changing the gate voltage of the device.

An artist’s representation of a nanobioelectronic device incorporating alamethycin biological pore. In the core of the device is a silicon nanowire (grey), covered with a lipid bilayer (blue). The bilayer incorporates bundles of alamethicin molecules (purple) that form pore channels in the membrane. Transport of protons though these pore channels changes the current through the nanowire. (Image by Scott Dougherty, LLNL)

From the abstract:

We present a versatile hybrid platform for such integration that uses shielded nanowires (NWs) that are coated with a continuous lipid bilayer. We show that when shielded silicon NW transistors incorporate transmembrane peptide pores gramicidin A and alamethicin in the lipid bilayer they can achieve ionic to electronic signal transduction by using voltage-gated or chemically gated ion transport through the membrane pores.

The work is in the early stages, the researchers note, but Noy points out that with “the creation of even smaller nanomaterials that are comparable to the size of biological molecules, we can integrate the systems at an even more localized level.”