Build a Network, Cellular Style

Bio-based molecular machines mechanically extrude tiny tubes and form networks, aiding in the design of self-repairing materials.

Image courtesy of Sandia National Laboratories
Nature’s molecular machine, kinesin, forms complex networks of tiny tubes made of polymers by converting chemical energy into mechanical work (schematic drawing, top). The microtubules (green) pull polymer nanotube networks (red) from polymer reservoirs (fluorescence image, bottom).

The Science

Inside plants, microbes, and other living things, cells quickly and continuously create transport networks, which move nutrients and wastes. The networks’ diversity and stability inspired scientists to design a process that co-opts natural biomolecular protein machines to extrude tubes and assemble them into networks.

The Impact

This development could lead to new pathways to make complex, robust polymer structures using biological molecules. Also, exploiting biomolecular machines to continuously assemble reconfigurable networks may enable a new class of self-healing materials. These self-repairing materials could lead to longer lasting solar cells, automatically repairing damage from long exposures to sunlight.


For the first time, biomolecular machines have been exploited to perform mechanical work to deform and dynamically assemble complex, far-from-equilibrium polymer networks. In biology, tubular structures formed from proteins, e.g., microtubules, function as highways for transporting small molecules. These complex networks could be used to create self-repairing, long-lasting materials. The challenge is that artificial versions of these tubular highways are not very robust. Further, today’s synthesis methods cannot create the diverse structures needed. In contrast, cells produce intricate structures. Biology’s ability to direct formation and deformation of networks to manage assembly processes inspired scientists at Sandia National Laboratories. The scientists used biomolecular machines, specifically kinesin motors, to rapidly and continuously assemble networks composed of nanotubes. The tubes were made from block copolymers, a synthetic analogue for the molecules used by nature. These mesoscale networks were hundreds of micrometers to tens of millimeters in size and composed of tubes, 30-50 nanometers in diameter.  Remarkably, the mechanical energy generated by kinesin motors was sufficient to deform the reservoir capsules of polymer and pull out nanotubes. This mechanical work also enabled rapid and continuous assembly of large-scale, one-dimensional nanotubes that can transport small molecules or nanoparticles. Adding a synthetic lipid made the building block polymer in the reservoir more fluid and enabled adjustment of the size and morphology of the extruded tubes. Using biomolecular machines to continuously assemble one-dimensional arrays may enable a facile entry into a new class of self-healing materials for electronics and solar cells, among other uses.


George Bachand
Sandia National Laboratories


U.S. Department of Energy, Office of Science, Basic Energy Sciences, including support of the Center for Integrated Nanotechnologies, an Office of Science User Facility.


W.F. Paxton, N.F. Bouxsein, I.M. Henderson, and G.D. Bachand, “Dynamic assembly of polymer nanotube networks via kinesin powered microtubule filaments.” Nanoscale 7, 10998-11004 (2015). [DOI: 10.1039/c5nr00826c]

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