PNNL

As the saying goes, imitation is the sincerest form of flattery. And when it comes to nature, science is no exception.

Biomimicry is the goal for many researchers looking to copy—and potentially improve on—nature’s example as they create new materials for a range of applications. One such example is peptides, the chains of amino acids that serve as building blocks for proteins.

In the synthetic world, one version of manmade peptides is called peptoids. Peptoids combine the merits of highly stable and efficient synthetic polymers with programmable and compatible biomolecules. Lacking requirements for symmetry and hydrogen bonds in the molecular chain, researchers have greater flexibility in designing peptoid-based systems to achieve different structures than seen in natural systems.

A new review paper, led by senior research scientist Chun-Long Chen and featured on the cover of Accounts of Chemical Research in January, summarizes efforts and advances by Pacific Northwest National Laboratory (PNNL) scientists in developing sequence-defined peptoids. By rearranging the molecular sequence of peptoid chains, the researchers are working to design new biomimetic materials that can not only self-assemble into responsive, reconfigurable, self-healing materials, but also influence how other inorganic components form and organize.

Peptoid progress

During the last five years, nearly a dozen separate studies published in Nature Communications, Nature Materials, Small, and other scientific journals have provided details about PNNL’s peptoid-related biomimetic research. These studies described new findings and applications such as self-forming nanotubes for water filtration, nanoparticles for delivering cellular drug therapies, and peptoids for controlling the predictive synthesis and formation of plasmonic gold nanomaterials.

The new account provides a discussion and perspective on these advances in three key areas:

• using protocols for the design and synthesis of amphiphilic peptoids—chains that both attract and repel water—and their crystallization methods,
• tuning peptoid-peptoid and peptoid-surface interactions for controlled assembly of amphiphilic peptoid oligomers into hierarchically structured crystalline nanomaterials, and
• designing amphiphilic peptoids as surfactant-like molecules for controlling the formation of inorganic nanomaterials.

“Significant achievements have been made in these areas, but to the best of our knowledge, review articles covering these topics have not been published,” said Chen, who also holds a dual appointment at the University of Washington’s Department of Chemical Engineering. “By integrating the results of recent studies, we hope to stimulate the research interest of chemists and materials scientists, improving the ability of scientists to design and synthesize sequence-defined molecules with functions improved over natural materials,” Chen added.

The goal, said Chen, is highly programmable and robust materials that are superior to those found in nature for various applications.

Accounts of Chemical Research is a high-impact publication of the American Chemical Society. The journal publishes concise and critical reviews of basic research and applications in all areas of chemistry and biochemistry on an invitation-only basis. Each account focuses on advances from projects within the author’s specific research area.

The PNNL account, “Programming amphiphilic peptoid oligomers for hierarchical assembly and inorganic crystallization,” was supported by the U.S. Department of Energy’s Office of Science through its Basic Energy Sciences Biomolecular Materials Program and Center for the Science of Synthesis Across Scales, an Energy Frontier Research Center led by the University of Washington. Bin Cai and Zhiliang Li contributed to the paper during their time as postdoctoral researchers in Chen’s group at PNNL.