Focus on: The Kotov Lab, University of Michigan

My Note: I just saw an interesting title to an abstract "Chiroptical Kirigami Modulators for Terahertz Circular Dichroism Spectroscopy of Biomaterials" which lead to me this page. So many interesting things are being done in areas I have never heard about before. 

http://www.umkotov.com/

Welcome to Biomimetic Nanostructures!

The “building blocks” of living organisms are nanoscale in dimension. Capable of spontaneous self-assembly, they form complex biological machinery with exceptional energy efficiencies of 89-95%. These nanoscale biological components also assemble into biocomposites with often-astounding combinations of properties – strength, density, transparency, ion conductivity and others. One can poses a fundamental question: can such machinery and materials can be reproduced using abiotic, inorganic building blocks that are also capable of self-assembly? The current body of knowledge accumulated for biomimetic nanostructures indicate that the answer is 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.

Inorganic nanoparticles can produce multicomponent assemblies with sophisticated geometries, for instance left- and right-handed helices or spiky mesoscale hedgehog particles. These non-biological structures can have surprising similarities with biological nanostructures despite their vastly different ingredients (i.e. inorganic nanoparticles vs. biomacromolecules). These similarities arise because the forces that govern the solution dynamics of these two very different classes of nanoscale structures have a lot in common. While the accurate description of forces between nanoscale structures is an ongoing scientific challenge, the experimental and technological conditions needed to utilize the convergent technologies involving inorganic nanostructures is remarkably simple once the fundamental parallels in their interactions are recognized.

The rapid and controllable assembly of inorganic nanostructures can be realized because the attractive interactions between inorganic nanostructures are typically stronger than those between biological building blocks. The change in entropy and enthalpy for association of inorganic nanoparticles with each other are favorable. The complex interdependence of the forces between nanoscale structures, which determine their mutual organization and self-assembly patterns, can be simplified when nanoparticles with high anisotropy, and especially nanoplatelets, are employed. Materials designed in such a way form a large class of biomimetic layered nanocomposites, and examples of their technological implementations are abundant.

Replication of the brick-and-mortar structure of tough iridescent seashells has led to a family of biomimetic composites made from graphene, clay, cellulose, and other components. These composites have revealed previously unattainable combinations of useful properties, including mechanical robustness and rapid ion transport. High electrical conductivity and spectrally tunable optical absorption have became possible due to the translation of biological patterns to abiotic semiconductor and metallic nanocomponents. Such materials have in turn engendered the construction of a large family of energy storage and biomedical devices. They also serve as membrane, load-bearing, and tissue-mimicking components in electronic devices.

Our current studies are aimed at the further development and generalization of the toolbox of experimental, theoretical, and computational techniques for the engineering of biomimetic nanostructures. Current topics in this area include chiral inorganic nanomaterials, biosimilar inorganic organelles, and pollen-like hedgehog particles, among others. The motivations behind this research abound, including the ongoing quest for ultrastrong multifunctional composites, materials for energy storage, and biomedical implants. The new engineering fields emerging from these topics include the convergent nanosystems for catalysis of ‘hard’ reactions, safe and effective antimicrobial agents, and machine vision.

With an appreciation of the technical challenges inherent in these problems, we have forged collaborations with colleagues around the globe. We value creativity, integrity, and tenacity in every person with whom we work.

Nicholas A. Kotov