This tiny molecular trick makes spider silk almost unbreakable
Researchers have uncovered the molecular interactions that give spider silk its remarkable combination of strength and flexibility. The discovery
Researchers have uncovered the molecular interactions that give spider silk its remarkable combination of strength and flexibility. The discovery could help scientists design new bio-inspired materials for airplanes, protective gear, and medical uses, while also offering insight into neurological disorders such as Alzheimer’s disease.
The study, published in the journal Proceedings of the National Academy of Sciences by scientists from King’s College London and San Diego State University (SDSU), outlines fundamental design principles that may guide the creation of a new generation of high-performance, environmentally friendly fibers.
Importantly, the research is the first to explain how the amino acids within spider silk proteins interact in a way that allows them to act like molecular “stickers,” holding the material together as it forms.
Chris Lorenz, Professor of Computational Materials Science at King’s College London and leader of the UK research team, highlighted the broad potential of the findings. “The potential applications are vast — lightweight protective clothing, airplane components, biodegradable medical implants, and even soft robotics could benefit from fibres engineered using these natural principles,” he said.
Why Spider Silk Is Stronger Than Steel
Spider dragline silk is known for its extraordinary performance. Pound for pound, it is stronger than steel and tougher than Kevlar — the material used to fabricate bullet-proof vests. Spiders rely on this material to build the structural framework of their webs and to suspend themselves, and scientists have long been fascinated by how nature produces such an exceptional fiber.
This type of silk is made inside a spider’s silk gland, where silk proteins are stored as a thick liquid called “silk dope.” When needed, the spider spins this liquid into solid fibers with remarkable mechanical properties.
Scientists already knew that the proteins first gather into liquid-like droplets before being pulled into fibers. However, the molecular steps that connect this early clustering to the final strength of the silk had remained a mystery.
The Molecular Interactions Behind Silk Formation
To solve this puzzle, an interdisciplinary team of chemists, biophysicists, and engineers used a range of advanced computational and laboratory techniques. These included molecular dynamics simulations, AlphaFold3 structural modelling, and nuclear magnetic resonance spectroscopy.
Their analysis revealed that two amino acids, arginine and tyrosine, interact in a specific way that causes the silk proteins to cluster together at the earliest stages. These interactions do not disappear as the silk solidifies. Instead, they remain active as the fiber forms, helping to build the intricate nanostructure that gives spider silk its exceptional strength and flexibility.
“This study provides an atomistic-level explanation of how disordered proteins assemble into highly ordered, high-performance structures,” Lorenz said.
Links to Brain Science and Alzheimer’s Research
Gregory Holland, an SDSU professor of physical and analytical chemistry who led the US side of the study, said the chemical complexity of the process was unexpected.
“What surprised us was that silk — something we usually think of as a beautifully simple natural fiber — actually relies on a very sophisticated molecular trick,” Holland said. “The same kinds of interactions we discovered are used in neurotransmitter receptors and hormone signaling.”
Because of this overlap, the researchers believe the findings may have implications beyond materials science.
“The way silk proteins undergo phase separation and then form β-sheet-rich structures mirrors mechanisms we see in neurodegenerative diseases such as Alzheimer’s,” Holland said. “Studying silk gives us a clean, evolutionarily-optimized system to understand how phase separation and β-sheet formation can be controlled.”
