Researchers from the RIKEN Center for Sustainable Resource Science (CSRS) and RIKEN Pioneering Research Institute (PRI) in Japan together with collaborators from the University of Münster, Germany, have developed a new hydrogel that offers significant advantages over others currently on the market in the field of biomaterials. Based on a single synthetic peptide called FQ(Pyr), the new hydrogel has a highly organized structure made from nanofibers that contain tiny water channels. The molecules within each nanofiber all point in the same direction, creating an electrical polarization along the fiber. This means that in addition to being strong and flexible, the new gel could be used to transport ions, generate electrical signals when squeezed, or have other advanced interactions with biological tissues. The findings were published in Nature Communications.
Hydrogels are biomaterials that resemble Jell-O. Scientists are trying to develop hydrogels made from peptides-protein building blocks that are common in all cells and tissues-because unlike silicone, they can interact with biological tissue and be recycled by the body.
They are also known to naturally organize themselves in water. For them to be most useful in biological systems, they need to be strong and flexible, and also have organized electrical properties. Kenichiro Itami and his team at RIKEN CSRS / PRI have now discovered how this can be accomplished.
The innovation
Strong peptide hydrogels are created by capping the ends of peptides with an aromatic ring-like structure. The peptides can then stack together nicely and form structured fibers, which creates strong, yet flexible gels. But if you look at these kinds of hydrogels under a microscope, the molecular network is messy, with the water inside sloshing around randomly in all directions. Uncapped peptides can form a structured network with functional channels, but without the aromatic rings, they are like a plate of spaghetti, weak and not very gel-like.
The researchers solved this trade off by inserting an extra-large aromatic ring onto the peptide backbone, not at the ends. They created the synthetic peptide FQ(Pyr) by joining two peptides, phenylalanine and glutamine, and attaching a pyrene group to the side of glutamine. When the synthetic peptide was placed in highly alkaline water, it dissolved into unassembled molecules. Slowly adding an acidifier to the mix caused it to begin self-assembling. At around a pH of 4, a translucent gel had formed. When tested, it proved strong and flexible. Violently shaking the gel caused it to break apart, but after 24 hours, it had healed itself and reformed into the same quality gel.
The gel has tiny water channels and is electrically polarized
Super-high 1.7 Å resolution cryo-electron microscopy, which can see details 6 million times smaller than a millimeter, showed that the gel was formed from uniform helical nanofibers. The near-atomic resolution imaging showed that each nanofiber contained five tiny water-filled channels. "Surprisingly," says Itami, "the water molecules were arranged in a highly ordered manner. At the same time, the peptide molecules were all oriented in the same direction. This combination produced an electrical polarization along the nanofiber that makes this hydrogel unique." The cross-section of each nanofiber revealed a consistent structure in which four units were arranged around the central water channel. Each of the units contained 12 of the synthetic peptides arranged around a smaller water channel.
Why is the electrical polarization so important?
Capped peptide hydrogels have limited function. They can be used as scaffolds for growing replacement tissue, or as an injectable pill that will release a drug into surrounding tissue. But the electrical polarity in the new hydrogel means that it can be used in more advanced ways. According to Itami, it could be used to control the movement of water or ions, respond to electric fields, generate electrical signals under pressure, or interact with cells and biological molecules. With these properties, the gel could be used in electric-responsive artificial muscles or in targeted, "smart" drug delivery triggered by an electrical signal.
"When I first saw the cryo-EM structure, I was so excited that I couldn't sleep that night!" says Itami. "It was astonishing to discover that such a small and structurally simple molecule could self-assemble into such as exceptionally beautiful helical supramolecular nanofiber."
"The most striking aspect of this work is its simplicity and beauty: a minimal molecular design gives rise to an extraordinarily ordered, self-healing structure with emergent electrical properties."
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Ueda et al. (2026) Atomic-precision π-driven peptide hydrogel nanofibers with ordered water channels. Nat Commun. doi: 10.1038/s41467-026-75984-9
