Biomolecular Self-Assembly of Nanorings on a Viral Protein Template.

Although there have been many advances in synthesizing nanoparticles, their assembly into deterministic and controllable patterns remains a major challenge. Biological systems operate at the nanoscale, building structural components with great chemical specificity that enable the processes of life. By adapting them to our needs, it is possible to utilize well-defined and well-controlled scaffolds to produce materials with novel properties resulting from precise ordering on the nanoscale. This approach uses spatial arrangement instead of nanoparticle size, shape, or composition to control material properties through the collective interactions between neighboring nanoparticles. Here, we demonstrate the use of tobacco mosaic virus (TMV) coat protein as a template to self-assemble plasmonic nanoparticles. Surface plasmons are resonant oscillations in the free electrons of a metal that are excited through interaction with light. These plasmonic oscillations can couple together, giving rise to more complex modes like plasmonic ring resonances that can be used to tune the response to incident light. By exploiting the self-assembling properties and chemical addressability of TMV coat protein, we can utilize site-directed mutagenesis and bioconjugation strategies to produce highly symmetrical plasmonic nanorings, as evidenced by transmission electron microscopy (TEM). Thus, we show the utility of viral proteins in designing and assembling nanostructured building blocks for advanced materials.

Alcohol-perturbed self-assembly of the tobacco mosaic virus coat protein.

The self-assembly of the tobacco mosaic virus coat protein is significantly altered in alcohol-water mixtures. Alcohol cosolvents stabilize the disk aggregate and prevent the formation of helical rods at low pH. A high alcohol content favours stacked disk assemblies and large rafts, while a low alcohol concentration favours individual disks and short stacks. These effects appear to be caused by the hydrophobicity of the alcohol additive, with isopropyl alcohol having the strongest effect and methanol the weakest. We discuss several effects that may contribute to preventing the protein-protein interactions between disks that are necessary to form helical rods.

Improving the Thermal Stability of NMC 622 Li-Ion Battery Cathodes through Doping During Coprecipitation.

Increasing the Ni content of LiNixMnyCo1-x-yO2 (NMC) cathodes can increase the capacity, but additional stability is needed to improve safety and longevity characteristics. In order to achieve this improved stability, Mg and Zr were added during the coprecipitation to uniformly dope the final cathode material. These dopants reduced the capacity of the material to some extent, depending on the concentration and calcination temperature. However, these dopants can impart substantial stabilization. It was found that the degree of stabilization is strongly dependent on the calcination temperature of the material. In addition, we used synchrotron X-ray diffraction during thermal breakdown to better understand why the different dopants impact the thermal stability and confirm the stabilization effects of the dopants.