DNA nanobots are microscopic structures that assemble themselves from DNA components. Recent research in DNA nanotechnology has brought self-assembling nanorobots a step closer to reality, but getting them to build into large objects is still challenging. Although, UNSW researchers, with colleagues in the UK, have figured out a piece of the puzzle and are a step closer to controlling self-assembling DNA nanobots’ dimensions.
Nanobots can already build themselves on a tiny scale, and scientists can program pre-made ones to do minimal and straightforward tasks. Medical researchers have used them to deliver drugs to cancer cells or position small electrical components.
But the ultimate goal is for the nanobots to assemble into any size and stop when done. You’ve probably seen it in the movies – for example, Iron Man’s suit forming itself from apparently nothing at the push of a button (fast forward to 1min 54 sec):
In the real world, they’ll be used in the health and medical field to do things like unclogging arteries and healing wounds.
The UNSW researchers’ new design theory explains how to control the length of self-assembling nanobots in the absence of a mold (confinement) or template.
Lead author Dr. Lawrence Lee of UNSW Medicine said:
Traditionally, we build structures by manually assembling components into the desired end product. That works quite well and easily if the parts are large, but as you go smaller and smaller, it becomes harder to do this.
The UNSW team uses biological molecules and molecular self-assembly to get the tiny individual components to build themselves into larger structures. The hard part is knowing how to program these building blocks to first self-assemble into a specific form, then stop when they reach the correct dimensions.
So, what they did was synthesize DNA subunits called PolyBricks. Each unit is encoded with the master plans that dictate a pre-defined structure of set length.
Dr. Lee said the PolyBricks are like microbots in the sci-fi film Big Hero Six. He said:
In the film, the ultimate robot is a bunch of identical subunits that can be instructed to self-assemble into any desired global form.
They control the dimensions of their built structures using a design principle known as strain accumulation.
Dr. Lee explained:
With each block we add, strain energy accumulates between the PolyBricks, until ultimately the energy is too great for any more blocks to bind. This is the point at which the subunits will stop assembling.
To control how many PolyBricks are joined together, they modified their DNA design sequence to regulate the amount of strain added with each new block. This dictates the length of the final structure.
Dr. Lee said:
Our theory could help researchers design other ways to use strain accumulation to control the global dimensions of open self-assemblies.
Dr. Jonathan Berengut, Ph.D. graduate and lead author, added:
It’s this type of fundamental research into how we organize matter at the nanoscale that’s going to lead us to the next generation of nanomaterials, nanomedicines, and nanoelectronics.
This mechanism could also be used to program more complex shapes, so the applications are endless.