Spider silk is another type of non-insect species of silk. It is soft and delicate, but strong and resilient. Commercial production of this silk comes from some Madagascan species, including Nephila madagascarensis, Miranda aurentia, and Eperia. The spinning tubes are located in the fourth and fifth abdomen of a frame, and the accumulated fibers come out four or five times a month. Spider silk is not used in the textile industry due to high production costs; however, durability, and extreme resistance to temperature and humidity make it essential for cross-hair in optical instruments.
Spider silk
Spider
silk is a protein fiber that is spun by spiders. Spiders use their silk to make
nets or other structures, which act as adhesive nets to catch other animals or
act as nests or cocoons to protect their offspring, or to trap prey. They can
use their silk to hang themselves, float in the air, or move away from
predators. Most spiders change the thickness and viscosity of their silk for
different uses. Although a method of forcibly collecting silk from a spider has
been developed, it is more difficult to collect silk from many spiders than
from silk-spinning creatures such as silkworms. All spiders produce silk, even
in non-web building spiders, silk is closely related to love and mating. Silk
produced by females provides a transmission channel for male vibrating love
signals, while mesh and draglines provide a substrate for female sex
pheromones. Researches on the silk production of male spiders during sexual
interaction are also common throughout phylogenetically extensive taxa.
However, the efficacy of male-produced silk in mating has received very few
studies.
Spider silk history
For
thousands of years, humans have associated spiders with spinning and weaving
just look at the Dine stories Spider-Woman or the ancient Greek myth of
Arachne. The first large-scale weaving with spider silk discovered was done in
the late 1800s and it was the brainchild of Jacob Paul Camboue, a French Jesuit
priest. As part of his missionary work, Camboue was sent to Madagascar, the
home of the golden orb spider. He was also an entomologist and was probably
fascinated by the idea of collecting spider silk to compete with the Chinese
silk industry. A colleague of Camboue, M. Nogue, designed and built a device
that can extract silk from 25 spiders at once without harming them. They
collected silk and woven it into a hanging bed set that was on display at the
Exposition Universelle in Paris in 1900.
The
fabric was an absolute sensation, but spider silk was considered too
labor-intensive and the original piece was lost over time. More than a century
later, Simon Peers and Nicholas Godley learned about Camboue and his project
and decided to try their hand at making spider-silk fabric. In a span of five
years, two Madagascar residents have teamed up with a group of 80 locals to
collect and harvest spider silk from more than a million golden orb spiders to
create a usable yarn. In 2008, the yarn
was then woven into a beautiful fabric.
Spider silk properties
Each
spider and each type of silk has a set of mechanical properties that have been
optimized for their biological activity.
i.
Spider silk is a protein fiber that is spun by spiders.
ii.
It is a semi-crystalline biopolymer with a unique combination of high tensile
strength, high elasticity, and high modulus.
iii.
The tensile strength of dragline silk is comparable to that of high-grade alloy
steel and about half as strong as an aramid filament, such as a Twaron or
Kevlar.
iv.
It is five times stronger than steel on a weight-by-weight basis.
v.
It is finer than human hair
vi.
It is more resilient than any synthetic fiber and completely biodegradable.
vii.
It has a tensile strength of roughly 1.3 GPa.
Viii.
Energy density of dragline spider silk is roughly 1.2×108 J/m3.
ix.
It is extremely flexible, some are able to stretch up to five times their
comfortable length without break.
x.
Strength and flexibility combine give dragline silks a very high toughness.
xi.
It can hold its strength below -40 °C and up to 220 °C.
Spider silk structure
Spider
silk, like many other biomaterials, has a classified structure. The primary
structure is the sequence of amino acids in its proteins, consisting mainly of
highly repetitive glycine and alanine blocks, which is why silks are often
referred to as block copolymers. At the secondary structure level, short
lateral-chain alanine is found mainly in the crystal domain of nanofibrils,
while glycine is mostly found in the so-called amorphous matrix consisting of
helical and beta-turn structures. It is the interaction between the hard
crystal part and the stranded elastic semi-amorphous regions, which gives the
spider silk its extraordinary properties. Compounds other than proteins are
used to enhance the properties of the fiber. Pyrrolidine has hygroscopic
properties that keep the silk moist and protect it from ants. It occurs in
adhesive threads, especially at high densities. Potassium hydrogen phosphate
releases hydrogen ions in an aqueous solution, resulting in a pH of about 4,
which makes the silk acidic and thus protects it from fungi and bacteria that
otherwise digest the protein. Potassium nitrate is believed to inhibit protein
degradation in acidic environments.
Spider silk Production
Spider
silk is a very special material because of its strength. Spiders do not produce
enough fiber for commercial use. So, many researchers are trying to create
these by bioengineering techniques in modified cells or animals. In this
method, the fibers are made into water-insoluble proteins and then converted
into fibers in severe cases that are far removed from the process used by
spiders.
The
production of spider silk differs in an important way from the production of
most other fibrous organic matter that is instead of constantly increasing as
the keratin in the hair, compressed feces of beetles made up of cellulose, or
even fibers in the cell walls of plants; It is spun according to demand from
special glands to liquid silk precursors.
The
process of spinning occurs when a fiber is pulled from the body of a spider, by
the spider's legs, the spider falls under its own weight, or in any other way,
including being pulled by a human. The term spinning is confusing because the
rotation of any material does not occur, but rather comes from the analogy of
textile spinning wheels. Silk production is a protrusion, like extrusion, that
is subtly induced by pulling the force into the finished fiber instead of
squeezing it out of the reservoir. The silk fiber is pulled through the silk
glands, which can contain both innumerable identical and different types of
glands on any spider species.
Spider silk applications
i.The
spider silk was used in research on mammalian neuronal regeneration.
ii.
It is used as a thread for crosshairs in optical instruments such as
telescopes, microscopes, and telescopic rifle sights.
iii.
It was used to create a set of violin strings.
iv.
It is also used to manufacture of military, medical and consumer goods, such as
athletic footwear, ballistics armour, personal care products, breast implant
and catheter coatings, mechanical insulin pumps, fashion clothing, and
outerwear.
v.
It is used to suspend inertial confinement fusion targets during laser
ignition.
vi. It has been used to create bio-lenses that can be used with lasers to create high-resolution images of the interior of the human body.
vii. Spider silk is used in bullet-proof garments
viii. It is used in wear-resistant lightweight clothing
xi. It is used in making ropes, nets, seat belts, parachutes
x. It is used in making rust-free panels on motor vehicles or boats
xi. Spider silk is used in making biodegradable bottles, bandages, surgical thread
xii. It is used for medical purposes such as artificial tendons or ligaments that support weak blood vessels.
xiii. It is also used in the medical industry are bandages that have the ability to reduce scarring versus using traditional bandages.
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