Welcome to Biomimetic Nanostructures!
Many building blocks of living organisms are nanoscale in dimension. Their size enables them to undergo Brownian motion and self-assemble into complex hierarchical materials. Furthermore, the energy for the construction of these materials is drawn from ambient thermal energy, which makes cellular machinery reach energy efficiencies of 89-95%. One can poses a question: can some parts of such materials and machinery be reproduced using abiotic, inorganic building blocks? The current body of knowledge accumulated for inorganic nanoscale particles leads to a definite “yes” for some and definite “no” for some others. We have dedicated our research efforts to understanding where the dividing line between these answers is.
The ability to self-assemble in complex structures, much like their biological counterparts, is the property intrinsic to all nanoparticles without exception. Most vividly, this property emerges in dispersions due to high mobility of nanoparticles, but the similar properties are also observed in solid state, for instance in nanocomposites. Varying nanoscale anisotropy from high (nanoplatelets) to intermediate (dipole, Janus) and subtle (chirality), inorganic nanoparticles can produce multicomponent assemblies with sophisticated geometries and connectivity patterns. Over past three decades, the complexity of these assemblies dramatically increased from nanoscale chains and nacre-like multilayers, to left- and right-handed helices and spiky hedgehog particles.
Theoretical predictions and experimental data indicate that the self-assembled structures from inorganic nanoparticles have distinct similarities with their biological counterparts, for instance proteins. They emerge because the symmetric relations and nanoscale forces that govern the solution dynamics of these two very different chemical species have a lot in common. Accurate elucidation of the nanoscale forces is an ongoing scientific challenge. However, the experimental and technological conditions needed to utilize them are remarkably simple once the fundamental parallels in their interactions are recognized.
Materials made using self-assembly of nanoscale platelets and other nanoparticles form a large class of biomimetic layered nanocomposites, and examples of their technological implementations are abundant. Replication of the brick-and-mortar structure of seashells has led to a family of biomimetic composites made from graphene, clay, cellulose, and many other components. These composites have revealed previously unattainable combinations of multiple useful properties: mechanical robustness, electrical conductivity, ion selectivity, charge accumulation, gas barrier, transparency, biodegradability and others. Such materials have in turn engendered the construction of a large family of energy storage, water purification, and biomedical devices. Utilizing self-assembling nanoscale components of both organic and inorganic in nature, many of them reveal direct structural parallels with various biological tissues and organs.
Our ongoing studies are aimed at the further development and generalization of experimental, theoretical, and computational techniques for biomimetic nanostructures. Current topics in this area include chiral inorganic nanomaterials, biosimilar inorganic organelles, and pollen-like hedgehog particles, among others. The new engineering fields emerging from these topics include the self-assembled nanosystems for chiral catalysis, effective antimicrobial/antiviral agents, and machine vision. Graph theory methods are being developed and used to design complex self-assembled structures and composites.
With an appreciation of the technical challenges inherent in these problems, we have forged collaborations with colleagues around the globe. We value creativity, integrity, inclusiveness, tolerance, and tenacity in every person with whom we work.
Nicholas A. Kotov