Scientists at Berkeley Lab's Molecular Foundry have developed what they believe is the largest 2-D polymer crystal self-assembled in water. As detailed in a recent issue of the journal Nature Materials, this new polymer couples the flexibility of natural proteins with the strength of synthetic materials.

"Our findings bridge the gap between natural biopolymers and their synthetic counterparts, which is a fundamental problem in nanoscience," says Ronald Zuckermann, director of the Biological Nanostructures Facility at the Molecular Foundry. "We can now translate fundamental sequence information from proteins to a nonnatural polymer, which results in a robust synthetic nanomaterial with an atomically defined structure."

The ultrathin, self-assembling, 'molecular paper,' as the researchers have dubbed it, is composed of peptoids, which are engineered polymers constructed from accessible and affordable building blocks. Inspired by nature, the polymers were designed to mimic the structure and functionality of proteins, and can even flex and fold like them. In contrast to natural proteins, however, each of the building blocks that comprise the peptoid-based sheets can be encoded with application-specific properties, according to the researchers.

"Mixing a 1:1 ratio of two oppositely charged peptoid polymers of a specific sequence in aqueous solution results in the formation of giant, free-floating sheets with only 2.7 nm thickness," the researchers state in their abstract. "The synthetic flexibility and biocompatibility of peptoids provide a flexible and robust platform for integrating functionality into defined 2-D nanostructures." Potential applications of the sheets could include biological detection and control of the flow of molecules.