A material made from hollow nanoparticles and DNA is exceptionally strong, especially considering how small its building blocks are. It could eventually be used to build extremely sturdy medical and electronic devices.
To make this super strong material, Horacio Espinosa at Northwestern University in Illinois and his colleagues started with particles made from metals like gold and platinum, each about 100 nanometres in size. Some were shaped like solid or hollow cubes with flattened corners, and others had material forming just the edges of a cube.
The best way to ensure that a material has the properties you want is to assemble it from scratch, one building block at a time. However, these nanoparticles are so tiny that assembling them becomes challenging. So, the team looked to DNA to act as a kind of glue.
They attached carefully synthesised molecules of DNA to the nanoparticles. When these were all mixed together, the bits of DNA that naturally attract each other chemically bonded, making the nanoparticles stick together and form a material.
Varying the shapes of the nanoparticle led to materials with different properties, which the researchers tested by putting them under pressure. They found that using the mesh-like nanoparticles produces a material with the highest strength and stiffness.
For instance, it was stronger than a conventionally manufactured material made from nickel with ten times larger building blocks – smaller particles typically make for stronger materials but had not been amenable to the same kind of manufacturing. And, it could withstand ten times more pressure than a nickel material made from solid nanoparticles.
Xiaoxing Xia at the Lawrence Livermore National Laboratory in California says that using DNA provides “an additional knob to control the interaction between the nanocrystal building blocks”, which opens new possibilities for creating large, ordered materials whose properties can be controlled by manipulating their structure.
This could lead to advancements in electronics or medical devices or even in transportation where light but strong materials are important for reducing emissions and boosting sustainability, says Espinosa. “In this study we reported only a tiny fraction of the many materials that can be made using DNA-directed assembly. Investigating many other combinations of constituents and architectures is high on our research wish list,” he says.