The researchers, from the University of California, Santa Barbara (UCSB), Asylum Research, University of California, Riverside, and the University of Texas at Austin, reckon the pulling curves they produced show that the material is self-healing.
"We're looking at mesostructures here - more than single molecules but much less than bulk materials," Helen Hansma of UCSB told nanotechweb.org. "We find exponential force increases when pulling capture silk at both the micron length scale and the centimetre length scale. This is a very simple mathematical relationship, but I believe it hasn't been observed before in stretching materials."
The researchers used the tip of a cantilever to pull molecules from a region of capture web under a droplet of calcium chloride solution. They believe that they captured a few molecules of spider silk each time that they carried out a pull. The longest pull was more than 3 µm.
The pulling curves also showed "saw-tooth rupture" events, which continued as the molecules underwent further pulling. The scientists say this indicates that spider capture silk is self-healing.
"Hopefully our work will contribute to the understanding of stretchy biomaterials and to the design of better stretchy synthetic materials," added Hansma. "We also want to learn about the evolution of these remarkable biomaterials."
The scientists reported their work in Nature Materials.