Over the past few years, miniaturisation has become the trend of domains ranging from electronics to materials.
Rapid progress in miniaturisation has led to the development of devices and electronic components that are as small as the components of living cells. This has opened up novel applications in bionanoelectronics.
Bionanoelectronics is a field in which the electronic and the biological components can work simultaneously. For example, devices such as palmtops or laptops can be compounded along with biological machines to enhance operating efficiency. In the past, research teams have tried to integrate biological systems with microelectronics, but have not met with success. A key challenge faced by various research groups in this domain is the incompatibility of the materials that are incorporated in the bionanoelectronic devices. The inorganic materials used in the fabrication of these bionanoelectronic devices often fail to operate efficiently in concert with the biological materials.
Aiding research in this direction, a team of researchers from the Lawrence Livermore National Laboratory (LLNL) in California has used a novel approach that employs lipid-coated nanowires to fabricate prototype bionanoelectronic devices. Instead of fabricating the biological machines with microelectronics, the team has used a nanoelectronic platform. Initially, to fabricate the bionanoelectronic platform, lead scientist Aleksandr Noy’s team employed lipid membranes that are omnipresent in biological cells. As these membranes have a natural tendency to form a stable, self-healing and impenetrable barrier to ions and small molecules, the LLNL team decided to use them in the bionanoelectronic platform.
The tendency of these lipid membranes to perform a large number of protein functions such as transport, critical recognition and signal transduction in the cell, attracted the team toward the lipid membrane. Further, the nanowires that formed a channel of a field-effect transistor were coated with the lipid bilayer membrane. The lipid bilayer shell acts as a barrier between the nanowire surface and the solution species. The team termed these coated nanowires the ‘shielded wire configuration.’ This configuration allowed them to use membrane pores as the only pathway for the ions to reach the nanowire. This was how they were able to use the nanowire device to monitor specific transport and also to control the membrane protein.
The novel approach proposed by the team at LLNL employed the same principles and designs that are employed by the human body, yet the team has used a very different materials platform. LLNL’s bionanoelectronic devices were built with inorganic materials, utilised electron currents and electric fields, and were powered by an external electric source.
According to the team, the advantages of the nanowire transistors are numerous: they have the capability to operate in ionic solutions, which is the native environment of most biological systems; an individual chip has a tendency to domiciliate hundreds of individual devices, providing redundancy ability to run parallel measurement and easy multiplexing possibilities; and the transistor provides an effective means of amplifying very weak signals generated by biological events.