The spider silk is a type of natural silk and it has a wide variety of properties and applications. Here is the basic things about the spider silk i.e. about the history , Types of spider silk, chemistry of spider silk , production, characteristics, different kind of properties ,etc.

1. NATURAL SPIDER SILK
 Natural spider silk is a natural protein biomaterial secreted by spiders through
their silk glands.
 Spider silk is a type of bio elastic fiber.
 Its mechanical properties and biocompatibility are incomparable with those of
other natural and artificial materials

2. HISTORY
 The ancient Greeks used spider silk to stop bleeding and heal
wounds
 Indigenous people used spider silk as a fishing line.
 World War II, spider silk was used as a crosshair in the optical device of the
sighting system of telescopes, guns, etc.

3. CHEMISTRY OF SPIDER SILK
 Spider silk is a protein fiber.
 Major amino acids in the silk proteins are alanine and glycine.
 Serine and praline are also present in significant quantities in some types of silk.
 Glycine-rich regions give spider silk its elasticity, forming amorphous areas in its
structure.
Alanine-rich regions link together through hydrogen bonds to form crystalline
areas that give spider silk its strength
Alanine
Glycine

4.  There are different kind of silk having different properties.
TYPES OF SPIDER SILK
 In a spider, these silk types are produced in different glands, so the silk from a
particular gland can be linked to its use by the spider.
Gland Silk use
Ampullate
(major)
Dragline silk – used for the web's outer rim
and spokes, also for the lifeline and for
ballooning
Ampullate
(minor)
Used for temporary scaffolding during web
construction.
Flagelliform Capture-spiral silk – used for the capturing
lines of the web.
Tubuliform Egg cocoon silk – used for protective egg
sacs.
Aciniform Used to wrap and secure freshly captured
prey; used in the male sperm webs; used
in stabilimenta(Web decoration).
Aggregate A silk glue of sticky globules.
Piriform Used to form bonds between separate
threads for attachment points.

6. CHARACTERISTICS OF SPIDER SILK
 Natural spider silk has the properties slightly better than the natural silk.
 Spider silk have better mechanical strength, temperature adaptability,
excellent elasticity, and super toughness, which is incomparable to those of
other natural fibers and synthetic fibers.
 It has better elongation than those of silk and nylon.
 The tensile strength of spider silk is about five times that of steel, similar to
that of Kevlar, and far better than those of silk, rubber, and nylon.
 Spider silk has the highest breaking energy, so its toughness is much better than
those of other materials.

7.  Because of all these properties spider silk can withstand great impact forces without
being damaged.
 The spider silk still has good stability at 200°C, and its structure will be destroyed
when the temperature goes beyond 300°C.
 Spider silk also performs well in low-temperature environments and still retains the
elasticity at low temperatures of −40°C.
 Spider silk is biocompatible, the main component of spider silk is spider silk protein,
which is protein in nature and non-toxic.
 Spider silk can be degraded under specific conditions, and the degradation products
can be absorbed by human tissues, so it is an ideal wound suture and prosthesis
making material.

8. MECHANICAL PROPERTIES
Spider silk has young’s modulus, tensile strength, and toughness
 Spider dragline silk shows higher tensile strength and extensibility than
silkworm silk and also tougher than most man-made fibers such as nylon 6,6;
Kevlar; and carbon fibers.
 Different types of spider silks evolved to have different functions and
mechanical properties.
 The tensile strength of dragline silk is higher than that of other types of
spider silk.

9. FACTORS AFFECTING THE STRENGTH OF SPIDER SILK
 The mechanical properties of the dragline silk, which is forcibly spun from
spiders, are related to the spinning speed.
 A high spinning speed results in a high initial Young's modulus and
fracture strength with a decreased breaking strain.
 Therefore, the spinning speed should be controlled uniformly to obtain spider
silk with uniform mechanical properties.
1)Spinning speed

10. 2)Nanofibrillar Structure
 Spider dragline and consist of bundles of twisted nanofibrils (30–35 nm in
diameter)
 This interconnection of the nanofibrils is believed to contribute to their high
toughness and strength.

11. 3)Nano-Fishnet Structure
 β-sheet crystallites form a nano-fishnet like structure in the amorphous region.
 Which contributes to the remarkable mechanical properties of spider silk.
 β-crystallites are formed from the folding and packing of new β-sheets on the
existing ones by pleating of the repetitive protein chains.
 The β-crystallites are aligned along the fiber axis during extrusion and stretching in
fiber spinning, which act as nodes of the “fishnet” and enhance the fiber strength

12. 4)The Multi-Layered Core–Shell Structure
 Spider dragline silks exhibit a skin–core structure.
 It consists of five layers; lipid layer, glycoprotein layer, skin layer, outer
core, and inner core.
 Only the two core layers contain known silk proteins (MaSp1 and MaSp2),
which are the major contributors to the mechanical properties of spider
silk, which give high mechanical strength to the silk

13. Modification of Spider Silk by Inorganic Nanomaterials
 Inorganic nanomaterials are used to enhance the properties of spider
silk.
 Hybrid materials tend to exhibit specific package of properties due to
complementing at least two different types of materials.
 In a hybrid spider silk, spider silk provides outstanding mechanical and
biocompatible properties while inorganic nanomaterials may offer
functional features to harness high-performance hybrid materials.

14. 1)Metal Nanoparticles
 Spider silk act as a template for the addition of metal nanoparticles.
 Gold particle introduced into spider silk to get outstanding physicochemical
property of gold nanoparticles, electrical conductivity, with a mechanical super
contracting property of spider silk fibers to produce a novel high-performance
material.
 To enhance the antimicrobial properties of spider silk, blending it with silver
nanoparticles having exceptional antibacterial properties.
 Metal nanoparticles like Zink, Aluminum, or titanium introduce into spider silk
to increase the toughness and produce extra tough fibers.

15. 2)Metal Oxide Nanoparticles
 Metal oxide nanoparticles is promising agent for the preparation of hybrid
materials with spider silk.
 Magnetite (FeO) nanoparticles were used to provide well-defined and
relatively stable silk coatings, possibly due to hydrogen bonding interactions at
the oxide-silk interface.
 By using the magnetic property of magnetite, spider silk can be used in audio
devices.
 Ceria (CeO) nanoparticles introduced into spider silk and it gives new
mechanical and optical properties to the spider silk. The resulting
optical fluorescent spider silk nano hybrids could be used in different
biomedical or sensing applications.

16.  Modification of native spider silk fibers with nanoparticles of zirconia (ZrO ) and
hafnia (HfO ) doped with rare earth elements introduce luminescent properties
and it can be used in biosensors and bio-imaging applications.

17.  By fabricating carbon nanomaterial into spider silk, it greatly enhances the
properties.
3)Carbon Nanomaterials
 Producing spider silk fibers reinforced by carbon nanotubes and graphene
yielded fibers with greatly improved mechanical properties surpassing
synthetic polymeric high-performance fibers.
 Carbon nanofibers were synthesized via pyrolysis, using spider silk as precursor, to
construct hybrid materials with superior oxygen reduction activity thus providing
opportunities in unconventional microbial energy harvesting.
 Hybrid fibers based on spider silk and carbon nanomaterials can be extensively use
as durable custom-shapeable, sensors, and actuating bio-devices.

18.  It is also useful as sutures, surgical implants, and tissue engineering scaffolds due
to their enhanced mechanical properties and as electrodes for brain/machine
interfaces and neuron regeneration due to the electro conductive properties of the
doping agent.

19. ABHIRAM H
MSc Nanoscience and nanotechnology
Kannur university