By Nick
Lavars
October 06, 2022
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Scientists have developed a novel treatment for
silkworm silk that makes it 70% stronger than spider silk Photo: Depositphotos
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Scientists have been working to replicate the
incredible properties of spider silk in some interesting ways. Farming spiders
to produce the material in great quantities is one possibility, but their
territorial nature doesn’t lend itself so well to these environments.
We’ve seen researchers make inroads by engineering
bacteria to produce their own
version of silk, and create synthetic
versions of it with many of the
same properties as spider silk. Some inventive advances have even
involved feeding
spiders graphene to make their silk
stronger, or adding nanocrystals to make synthetic versions stronger and
tougher than the real deal.
The silk that silkworms produce to build their
cocoons is another point of interest in these research circles. Silkworm farming
generates almost all commercially used silk around the world, but its lower
durability than spider silk sees its use mostly limited to fashion and
textiles. We’ve seen scientists address this by devising
chemical treatments designed to make silkworm silk stiffer, and
now a team from China’s Tianjin University has come up with a promising recipe
of its own.
Natural silkworm silk served as the team’s
starting point. The process involved boiling the silk in a bath of chemicals
that dissolves a glue layer that coats the core fibers of the silk, but
minimizes damage to the silk proteins. The silk was then solidified in a bath
of metals and sugars that enhance it further.
"Since silkworm silk is very structurally
similar to eggcase spider silk, which has
previously been demonstrated to do well in a mix of zinc and iron baths, we
thought to test this alternative method to avoid hazardous conditions used
elsewhere," said senior author Zhi Lin, a biochemist at Tianjin
University. "Sucrose, a form of sugar, may increase the density and
viscosity of the coagulation bath, which consequently affects the formation of
the fibers."
The team’s material was then manually spun and
drawn, forming thin silks akin to those of a spider, but “considerably stiffer”
than any known natural silks. The team found it also had a significantly higher
tensile strength than natural spider dragline silk, at 2 Gigapascal (GPa). This
also places it well ahead of a promising 1-GPa
synthetic silk we looked at last year.
"Our finding reverses the previous perception
that silkworm silk cannot compete with spider silks on mechanical
performance," said Lin.
The research was published in the journal Matter.
Source: Cell
Press via ScienceDaily