How do you build something on the smallest physical scales imaginable? Govind Menon an IIT graduate and now a professor at Brown University along with researcher Dr. David Gracias have found a way to create self-assembling three dimensional structures on the scale of nanometers by mimicking viruses.
The approach involves laying out a series of nearly two dimensional (completely flat) polygons in a certain formation. A small amount of special solder is then placed at the intersections of the polygons. When the system is heated, the solder melts, pulling the separate polygons up into place, forming a three dimensional structure.
“Our work is inspired by and mimics replication of viruses,” says Menon. In an interesting twist, this work may even shed light on virus self-assembly just as our understanding of some nanoscale biomolecular motors unexpectedly related to rotary car engines.”
One of the challenges of this work is deciding on the original layout of the two dimensional polygons pre-fold. Take a cube, for instance. There are several ways to lay six squares flat, fold them at the edges, and create a cube. Finding the ideal shape which will fold best when using the above mentioned technique is extremely difficult. As the shape grows more complex (i.e., as the polyhedra gets more sides) the number of ways it can be cut up increases greatly. In order to find the most effective way to fold them, Menon and his collaborators had to develop complex algorithms to test which would be the most effective without going through the immense amount of time required to experiment with them all.
This field as an exciting meeting point between several fields of science. Other work in this field includes attempting to build structures using DNA. DNA’s double helix structure happens to be extremely strong, and by pairing base pairs, strong shapes have been built made exclusively out of DNA. Others have attempted to design polyhedra which are flexible and can move. In these structures, the angle at each edge of the shape is changeable, while the length of each edge is not. A cube, for instance, does not fulfil these requirements.
In the future, Menon and Gracias hope to apply this technology to medicine, among other areas. For instance self folding polyhedra could ferry a drug to parts of the body that would otherwise not be reachable. However, much work is still to be done, and this is surely only the beginning of a new field of science brimming with potential.
(The article has been contributed by Ishaan Bhojwani, Science contributor)