Often scientists view viruses as nanomaterials of fixed sizes that are used merely as templates to synthesize other useful materials such as metal or metal oxide nanoparticles. Contrary to this view, in this issue Rego et al. from Tufts University (MA, USA) employ the elegant self-assembly mechanism of the tobacco mosaic virus (TMV) to create nanoscale building blocks with controlled dimensions, or what they affectionately call “baby” TMVs. They show that one can reproducibly create such viral particles by simply mixing purified coat proteins with RNA molecules of pre-designed lengths that contain the sequence, thus triggering coat protein self-assembly. The outcome is well-controlled nanoarchitectures and hybrid nanomaterials for a wide variety of applications including nanoelectronics and nanocatalysis.
Scaling up manufacturing of bionanotechnological products beyond pharmaceutical and diagnostic applications remains a major challenge in large part due to issues of feasibility and cost. In this issue, Rouvière et al. (Dupont) solve this problem by designing a polypeptide capable of self-assembly into higher-order structures that binds two distinct surfaces, namely pigments and hair. At the same time, the controlled solubility properties of this polypeptide permit its scalable production in Escherichia coli via inclusion bodies and a cost effective purification. This approach of combining multi-functionality with cost-effective production will find applications in materials science, biocatalysis, personal care and agriculture.
Enzyme immobilization to particles has become important in biotechnology, as it brings about substantial improvement in enzyme catalytic efficiency. But how important a factor is particle size when it comes to enzyme performance? While it is generally believed that the smaller the particle size, the higher the enhancement, in this issue Tsai et al. (University of Delaware, USA) present a different story. These researchers employ a simple method based on metal affinity coordination to directly conjugate two different enzymes onto quantum dots (QDs) of different sizes, which they use to systematically study the influence of particle size and QD/enzyme ratio on overall enzyme enhancement. Surprisingly, the authors show that enzyme proximity is the most important factor for activity enhancement, while the influence of particle size is relatively modest. These results are important in designing improved nanobiocatalysts for biofuel production, bioremediation, and drug design.