Tensile Strength and Projectile
Resistance in Spider Silk
Nima Nahvi and Josh Gordonson
Research II
Period 9
Mrs. Bland-Lamoureux
March 7, 2016
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Spider silk is known to be one of the strongest, sturdiest, and most elastic
substances there are on this planet. Compared to steel on " ‘a per weight ratio’ it is up
to five times stronger, and three times tougher than aramid fibre," as said so by Nexia
Biotechnologies Incorporation and the U.S. Army Soldier Biological Chemical Command
(SBCCOM), in their article "Man Made Spider Silks." Other than its strength and
toughness, spider silk is light and biodegradable, not to mention that it can bend 2550% its durability before it breaks. Steel can only bend up to 8% and Nylon only 20%
before it breaks.
Spider silk otherwise called BioSteel by the Nexia Inc. can be used to create
many advances in the fields of medical, military and industrial performance fiber
markets. The individual miniscule strands that spiders use in weaving their webs are so
strong that they can stop a bee going 20 mph dead in its tracks without breaking. If one
tiny strand can do that to a bee, thousands or
millions of strands spun together should stop a
bullet. In addition, the new methods of clothing
for war could also be used at home. Knowing
that spider silk is lighter and more flexible than
many materials, new clothing can be fashioned
Figure 1: Water droplets forming around the
waterproof spider silk (Borchardt)
out of it, ones that won’t rip as easily and
protect bodies much more efficiently from harsh conditions such as rain.
For hundreds of years people have been trying to farm spider silk, however,
there are two problems with this. One is that the spiders have to be spaced far apart,
so as to prevent them from eating one another, the other being that the silk hardens
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when it first comes in contact with air, therefore making it difficult to work with. In 1709
the French government asked Rene-Antoine Ferchault de Reaumur to find uses for
spider silk such as clothing. He then collected spider silk from egg sacks and tried to
create gloves and stockings, after some time he gave up because of the immense
amount of material it took to make only one pair of gloves (Lewis 1). Later on in the
eighteenth century, another Frenchman named Bon de Saint-Hilaire attempted to farm
spiders, but found out that because they eat each other, it is not efficient to do. In 1803
Daniel Rolt developed a silk-extracting machine that looked like a spool of thread on an
engine (Lewis 1). After attaching the silk to the spool, the engine was turned on and the
silk was extracted from the spider. Supposedly it could wind “18,000 feet of silk from
two dozen spiders in two hours.” (Lewis 1) Between 1866 and 1873 Burt G. Wilder
created an apparatus that immobilized the spider and held it in place for manual
harvesting. Supposedly he had pulled out “150 yards from the particularly cooperative
arachnid, then calculated that it would take 5000 animals to retrieve enough material to
make one dress.” (Lewis 1)
Because spider silk is so thin, it was used for
the crosshairs in rifle scopes, microscopes, and other
precision instruments. Ancient civilizations figured out
ways to use spider webs. For instance, the Greeks
used silk to help heal wounds, Australian aboriginals
used the silk as fishing line, and the natives in New
Guinea make bags, head gear, and fishing nets from
Figure 2: Fibroin is being squeezed out
of the tubes (Nieuwenhuys 1)
the silk (Lewis 1). Today, scientists are trying to further
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understand the exact chemical structure of spider silk so that they can replicate spider
silk in large quantities.
Some possibilities with spider silk are to create artificial tendons and ligaments,
parachute cords bullet proof vests, or even a building material made out of silk (Lewis
2). There are two ways to synthesize the spider silk, one way is to put the silk together,
piece by piece, on a high tech machine and the other way is to cut out the specific gene
in spider cells that makes the silk and use recombinant DNA techniques to make
bacteria produce the silk.
Unfortunately, scientists do not know enough about the chemical structure of
spider silk to construct it, so Randy
Lewis has used spider DNA to create
the liquid proteins in bacteria. After
the proteins are extracted from the
bacteria and placed in methanol, the
Figure 3: The Fibroin all wrapped up (microscope)
(Electron Microscope)
silk is formed. Spider silk has been
reported to be composed of two proteins,
spidroin 1 and spidroin 2 (Lewis 2). Together
these two proteins from a fiber called fibroin,
when fibroin is twisted together, it becomes
spider silk. At first, separate fibers of fibroin are
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Figure 4: Silk Fibroin (Garrel)
squeezed out of small tubes located on the spinners. After this, the spinners weave the
fibers together to create the spider silk.
For the most part, these two proteins only differ in the amount of tyrosine and
proline. Since the amino acid sequence repeats so much, it is determined that the silk
is a highly ordered structure. Most of spidroin 1 and spidroin 2 is composed of alanine
and glycine. The alanine is grouped in sections of 5-10 repeating amino acids, most of
the alanine is less organized and
holds regions of highly organized
beta sheets and amorphous
background sheets together
(Lewis 2). The rest of the alanine
is located in the beta sheets
along with lots of glycine.
Because the spider silk is
Figure 5: The sequence of a certian type of spider silk
(Oroudjev and Soares and Arcdiacon amd Thompson and
Fossey and Hansma)
arranged this way, the silk has
massive amounts of tensile
strength. Some other amino acids in the silk are glutamine, serine, leucine, valine,
proline, tyrosine and arginine. Because alanine and glycine are the two smallest amino
acids, and do not have any side-groups, it would make sense that they are in the spider
silk (Lewis 2). Due to the lack of side groups, the two amino acids can pack together
more tightly and form a more organized crystalline structure faster and easier (Lewis 2).
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According to George E. Goodfellow of Tombstone, Arizona a man that was shot
for six feet away in the left breast was protected by a silk handkerchief placed in his
pocket. After examining the wound, the bullet was found in a fold in the silk with two
layers of silk surrounding it. After several subsequent tests, it was found that the bullet
would normally go right through the body (Harp 2). Therefore, if a soldier were to wear
several layers of silk under or over their clothing, there would be a lower chance of fatal
wounds. By creating cloth or patches of layered spider silk and testing their tensile
strength, the most effective type of spider silk could be determined and then tested
using a projectile traveling at a fixed speed.
In the future, spider silk, artificial or not, will be used in military and commercial
situations. If possible, synthetic spider silk will be mass produced and sold to large
manufacturers that would spin or weave the silk into useful products such as parachute
cords or body amour. The use of spider silk, most likely will revolutionize the military
and civilian aspects of everyday life.
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Works Cited
Borchardt, John K. Soon, spider-silk togs and mussel glue? Soon, spider-silk togs and
mussel glue?. August 26, 2004. Online. October 27, 2005. <http://www.christian
sciencemonitor.com/2004/0826/p13s01-stgn.html>
Electron Microscope Lab. Online. 10/17/05 Internet.<http://biology.berkeley.edu/
EML/backgrounds.html>.
Greenburg, J.C.. Spider Feet. Online. 10/17/05 Internet. <http://www.andrewlost.com
/spider_feet_question_k1.htm>.
Harp, Joel M. “Bullets and Silk in the Old West.” Science Vol. 271 (Feb. 2, 1996): 580581.
Lewis, Ricki. Unraveling the Weave of Spider Silk. October 1996. Online. 10/17/05
Internet.<http://links.jstor.org/sici?sici=00063568%28199610%2946%3A9 %
3C636%3AUTWOSS%3E2.0.CO%3B2-F>.
Nexia Biotechnologies Incorporation. Man Made Spiders Silk. January 2002.
Online. 10/17/05 Internet. <http://www.azom.com/details.asp?ArticleID=1233>.
Oroudjev, E. and Soares, J. and Arcdiacono, S. and Thompson, J.B. and Fossey, S.A.
and Hansma, H.G. “Segmented Nanofibers of Spider Dragline Silk: Atomic Force
Microscopy and Single-Molecule Force Spectroscopy” Proceedings of the
National Academy of Sciences of the United States of America Vol. 99 (Apr. 30,
2002): 6460-6465.
Silk Fibroin Stocked Beta Sheet. Online. 10/17/05 Internet. <http://voh.chem.ucla.
edu/vohtar/winter02/C181/images/Silk_fibroin.JPG>.
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