CAREER: Programmable Assembly of Glycine-Rich Peptides on a Graphitic Surface

Kansas State University, Manhattan KS

Investigators

Abstract

NONTECHNICAL SUMMARY This CAREER award supports theoretical research, computer simulations, and validating experiments to design molecules that can be programmed to arrange themselves into complex devices. A modern smartphone that fits in a pocket has more computing power than a hefty laptop of 20 years ago, while also including a digital camera, GPS, and the ability to make wireless calls. The miniaturization of devices has been so successful that the size of some components is growing close to the size of molecules and atoms, requiring big changes in how devices are built. It is as if building sandcastles has given way to building tiny castles out of individual grains of sand. While making devices from individual molecules may be difficult, it can be done; living things make thousands of different proteins with single-atom precision, each performing a different function while often arranging themselves into larger, more complex structures. The goal of this project is to design protein-like molecules that are similarly able to arrange themselves, but in a way that can be easily programmed by a human engineer. To make imaging and design of the devices easier, the project is focused on molecules that arrange themselves on top of an atomically flat graphene surface. The research team will use computer simulations to optimize control over the arrangement, checking the computer predictions against experiments. This research should reveal new theoretical principles for designing future devices from single molecules. Also, the biological nature of the molecules means that they might be applied in medical applications. Undergraduate and graduate students, including those from minority groups underrepresented in scientific research, will participate, learning cutting-edge computational techniques. The research team also seeks to develop computer simulations of molecules for use in college classrooms and in K-12 outreach, letting students see how molecules move and giving them a feel for how the world works at this tiny level. The interactive simulations will include those aimed at helping students understand how medicines work and how new medicines can be designed. The educational modules and simulation programs will be made freely available to educators and the public, and will include English- and Spanish-language versions. TECHNICAL SUMMARY This CAREER award supports research to address a fundamental problem in engineering self-assembled structures: how to design molecular elements that possess both the flexibility to adopt arbitrary useful structures and the selectivity to adopt a unique programmed structure with high fidelity. The goal of the project is to develop a theoretical framework and computational tools for designing building blocks for programmable assembly. The project is focused on glycine-rich peptides that fold into unique conformations on graphitic surfaces and self-assemble in predictable ways. This peptide-graphene system seems optimal for creation of programmable materials because the effectively two-dimensional architecture simplifies imaging and reduces the peptides' conformational and configurational freedom, favoring ordered structures and facilitating analysis by theory and molecular dynamics simulation. The research team will use molecular dynamics simulations and state-of-the-art free-energy calculation techniques to screen large numbers of peptide sequences to find sets of elements suitable for programmable assembly. The computational predictions will be experimentally validated using atomic force and electron microscopy. The results of this project are anticipated to advance the field of molecular self-assembly by establishing theoretical and computational tools to find sets of molecular motifs with optimal interaction thermodynamics for programmable assembly of nanodevices. The project will involve the development of new algorithms and freely available software for enhanced sampling, free-energy calculation, and interactive molecular design, likely advancing the field of molecular simulation. This CAREER award also supports education activities related to the research area. The team will also create interactive educational modules leveraging easy-to-use browser-based simulations, which will be tailored to a graduate course on drug design, undergraduate courses on thermodynamics, and K-12 outreach activities. These modules will include English- and Spanish-language versions. Graduate and undergraduate students participating in the research, including some from populations historically underrepresented in science and technology fields, will gain exposure to nanoscience and advanced computational techniques. This project is jointly funded by the Condensed-Matter-and-Materials-Theory program in the Division of Materials Research and by the Established Program to Stimulate Competitive Research (EPSCoR). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.