Jayasinghe and his colleague Andrea Townsend-Nicholson of University College London partnered to test the ability of cells to form a thread with the polymer and survive the electrical fields necessary to create it. The polymer in question--medical-grade poly(dimethylsiloxane)--does not conduct electricity well but is extremely viscous. The two researchers created a needle-within-a-needle system, in which living brain cells in a medium flow through the inner needle and the polymer flows around it via an outer needle. By applying an electrical field of roughly 9.5 kilovolts, the researchers stretch a droplet of the viscous polymer into a superfine thread no wider than the cells themselves using the polymer's inherent electrostatic repulsion.
Compared with a control population of brain cells, those cells subjected to the electrical field did not show any ill effects and thrived up to six days after the experiment, according to the paper presenting the result in the November 13 issue of Biomacromolecules. "This has far-reaching implications and will enable significant advances to be made in technologies ranging from tissue engineering to regenerative medicine," the researchers write. And using different biopolymers might allow the creation of threads of different strengths and persistence. Perhaps in the future such living nanothreads might be spun directly into wounds.