Melik Demirel on Revolutionary Properties of Evolutionary Materials

Recent advances in the nanotechnology of materials combined with parallel improvements in biotechnology and synthetic biology, have demonstrated that we can achieve more complex biomimetic materials with properties engineered precisely to optimize performance.  Specifically, proteins provide unique advantages as advanced materials. For example, proteins can self-assemble into myriad structures, representing a unique opportunity to design functional materials.

On the right: Dr. Demirel is on a research exhibition boat in the Mediterranean capturing live squid

An important question coming out of these advances is if we can synthesize a material with evolutionary properties that can revolutionize how we design and manufacture next generation devices. An answer to this question lies in the secret of the evolutionary success of duplication in proteins. Tandem-repeat proteins, found throughout the tree of life and in all eukaryotes, feature a modular structure. These proteins exhibit a wide range of structures and functions, from soluble forms that serve to bind other biomolecules, to structural fibers such as squid ring teeth (SRT), collagens, elastin, and silks. Repetition in proteins intrinsically promotes stability through the periodic recurrence of favorable interactions, and modular reuse of already established components allows for a stepwise increase in complexity.

I am leading a group at Penn State University that is working on a new design principle for materials that could bridge biotechnology and materials science. Our design principle is based on the evolutionary concept of population dynamics, which considers the changes in the physical property of a population of materials from one generation. With this technique, we can program materials to evolve in time to attain dynamic functional properties based on external “selection” rules. More importantly, protein can evolve to new functionalities by gene mutations or duplications, which is unique advantage compared to inorganic materials [1].

Recently, we used a direct correlation between gene duplications and its impact on physical properties to demonstrate that tandem repetition of self-healing SRT protein sequences enhances physical properties [2]. This method opened the opportunity for the assembly of 2D layered materials (e.g., atomistically thin sheets) that are precisely controlled with nm resolution for application in electronic and optical devices. In parallel, we reported the development of a new technique to screen protein evolution based on laser-probing spectroscopy with sub-picosecond resolution.

Our results demonstrate, for the first time, relative quantification of protein based materials in real time for directed evolution. Hence, combining materials assembly and high-throughput screening, we could answer many fundamental questions in materials research, such as the fundamental long-range order in soft matter as well as development of new tools for advanced materials assembly. Programming physical properties through evolution introduces a new design rule for the understanding of materials engineering and design.

[1] Jung, H.; Pena-Francesch, A.; Saadat, A.; Sebastian, A.; Kim, D. H.; Hamilton, R. F.; Albert, I.; Allen, B. D.; Demirel, M. C. Molecular Tandem Repeat Strategy for Elucidating Mechanical Properties of High-Strength Proteins. Proc. Natl. Acad. Sci. U. S. A.2016, 113.

[2] Vural, M.; Lei, Y.; Pena-Francesch, A.; Jung, H.; Allen, B.; Terrones, M.; Demirel, M. C. Programmable Molecular Composites of Tandem Proteins with Graphene Oxide for Efficient Bimorph Actuators. Carbon. 2017, 118, 404–412.