Pictured is the delivery of a two-terminal nanoscale electronic sensor into single cells
Chemists and engineers at Harvard University have fashioned nanowires into a new type of V-shaped transistor small enough to be used for sensitive probing of the interior of cells.
NanoFETs,nanoscale field-effect transistors, could be used to measure ion flux or electrical signals in cells, particularly neurons. The devices could also be fitted with receptors or ligands to probe for the presence of individual biochemicals within a cell.
Human cells can range in size from about 10 microns (millionths of a meter) for nerve cells to 50 microns for cardiac cells and current probes measure up to 5 microns in diameter
* coating the NanoFET with a phospholipid bilayer — the same material cell membranes are made of — the devices are easily pulled into a cell via membrane fusion, a process related to that used to engulf viruses and bacteria.
* This eliminates the need to push the nanoFETs into a cell, since they are essentially fused with the cell membrane by the cell’s own machinery
The Harvard group, led by chemistry professor Charles Lieber, is now developing more sophisticated bioelectronics that will take advantage of transistors’ ability to send as well as receive electrical signals. They’re also working with a tissue-engineering group to develop implantable bioelectronics that could make better connections between the body and neural prosthetics such as those that control some artificial limbs. The probes, which are based on silicon nanowires, can be grouped in large arrays, so the researchers also hope to use them to get a picture of biochemical and electrical networks in the large groups of cells that make up tissues. Such measurements are difficult to make today.
The Harvard researchers are now collaborating with a group at MIT to incorporate the nanoprobes into medical devices, including scaffolds used to make artificial tissues. Circuits of nanowires could “innervate” an artificial tissue so that it could measure and respond to electrical signals propagating through the heart or brain. These bioelectronics might enable better communication between the brain and an artificial limb, for example