Scientists combine synthetic and biological nanoparticles to produce new metamaterials

Aalto University scientists have organized synthetic and biological building blocks in a single structure - combining virus particles (and other protein cages) with inorganic nanoparticles to form crystalline layer structures, or superlattices.

The research aims to develop hierarchically structured nanomaterials with tunable optical, magnetic, electronic and catalytic properties. Such nanomaterials are important for applications in sensing, optics, electronics and drug delivery.

By generating biohybrid 3D superlattices of nanoparticles and proteins, "the versatility of synthetic nanoparticles and the highly controlled assembly properties of biomolecules can be combined," explains Dr Mauri Kostiainen of Aalto University Department of Applied Physics, who led the research.

"Binary nanoparticle lattices have received so much attention because they can provide a way to prepare multifunctional metamaterials - periodic artificial materials not found in nature. In them, new properties arise from collective behaviour," explains Kostiainen.

For example, they showed that virus or ferritin protein cages can be used to guide the assembly of RNA molecules or iron oxide nanoparticles into superlattices, formed through tunable electrostatic interactions with charged gold nanoparticles.

"The gold nanoparticles and viruses adopt a special kind of crystal structure that doesn't correspond to any known atomic or molecular crystal structure and it has previously not been observed with nano-sized particles," said Kostiainen.

In bringing these kind of new materials to fruition, scientists turn the usually unwanted properties of viruses into something very useful, by employing the unique capability of highly controlled self-assembly of the virus particles.

The Academy of Finland funded the study.

The online article provides an in-depth description of this research project: https://dx.doi.org/10.1038/nnano.2012.220.

Youtube video link: https://youtu.be/lkkUe5xntNw