A (small) breakthrough in intracellular measurement

A (small) breakthrough in intracellular measurement

A team of chemists and engineers at Harvard University has created a V-shaped transistor that is small enough to probe sensitive cell interiors without damaging the cells the first new electrical measurement tool for intracellular studies in over 40 years. Measuring less than 50 nanometers in total size, the nanoFETs (nanoscale field-effect transistors) are significantly smaller and less bulky than the probes currently being used for intracellular measurement. The new devices were introduced in an August edition of Science in a paper by senior author Charles M. Lieber, the Mark Hyman, Jr. Professor of Chemistry at Harvard, and his colleagues.

A to-scale schematic of a kinked-nanowire electronic sensor probing the intracellular region of a cell. (Courtesy of Charles Lieber)

In addition to their small size, the nanoFETs can be easily inserted into a cell once they are coated with a phospholipid bilayer (which is the same material cell membranes are made of) allowing the devices to be pulled into a cell via membrane fusion. Lieber explains, “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[.] This also means insertion of nanoFETs is not nearly as traumatic to the cell as current electrical probes.”

The paper also describes the team’s work with introducing triangular “stereocenters” — fixed 120º joints — into the 1-D nanowires and creating kinks. The kinks make the nanostructures more complex. The team found that two stereocenters introduced into a nanowire in the proper “cis” orientation (groups of atoms oriented in the same direction) created a single V-shaped 60° angle. The created angle is perfect for a two-pronged nanoFET with a sensor at the tip of the V, allowing the two arms to be connected to wires and create a current through the nanoscale transistor. To view the paper, visit www.sciencemag.org/cgi/content/abstract/329/5993/830.

Christina D’Airo