Like all arthropods (the large group which
includes insects, scorpions, shrimp, and lobsters), horseshoe
or exoskeleton, that provides protection from predators.
Millions of tightly interwoven strands of a cellulose-like
material called chitin serve as a tough and flexible
glue that holds together the shell. The chitin in horseshoe
crabs is favored for research over that found in other arthropods
because it is very pure.
Chitin was first investigated in 1811 by Professor Henri Braconnott,
who discovered it in the cell walls of mushrooms. In the 1830s,
it was isolated in insects and named chitin. Chitosan, a derivative
of chitin, was produced in 1859, and since then, research has
been conducted to learn about the properties of chitin and
chitosan and develop commercial applications for their use.
Chitin is Excitin'
The combination of chitin's remarkable properties makes it
extremely versatile. Chitin is natural, non-toxic, non-allergenic,
anti-microbial, and biodegradable. It has a strong positive
charge, which allows it to bind with negatively charged surfaces
or materials, including metals, skin, and macromolecules such
Structure of Chitin
Cellulose, chitin, and starch are the three most abundant
organic compounds in nature. Cellulose and starch are key carbohydrates
that plants use as a food source and to build cell walls.
Chemically, chitin is a polysaccharide. A
polysaccharide is a polymer — a large molecule consisting of
smaller (and in this case, sugar) molecules strung together.
Chitin can be processed into many derivatives, the most readily
available being chitosan, which is formed when chitin is heated
with a chemical solution. Chitosan has some advantages over
chitin because it is more water-soluble.
Chemical Structure of Chitin
By the 1940s, almost 50 patents had been filed
for chitin-related products. But commercial development of
chitin proceeded slowly, partly because synthetic products
were already in use in some applications, and there was a lack
of strong federal support for chitin research and the development
of chitin products. In the mid-1970s, however, environmental
regulations were passed to limit the dumping of untreated shellfish
wastes in coastal waters, thus making the processing of chitin
from shellfish waste an economical way to comply with
the regulations and dispose of the thousands of tons of shellfish
waste produced annually. Today, nearly 200 patents have been
issued in the United States, in addition to those issued in
several other countries worldwide, and there are nearly 15
major processors of chitin and chitosan around the world.
Check Out the Many Uses of Chitin!
||Dr. Paul R. Austin pioneered chitin
research at the Unversity of Delaware.
Application: Early on it was found that chitin
had wound-healing properties. By the mid-1950s, chitin-coated
sutures were being used, which enhanced healing time by 35
to 50%. In the 1970s, researchers with the University
of Delaware Sea Grant College Program developed a method to spin pure chitin
filaments. These new chitin sutures could be absorbed by the
body, eliminating the need for surgical removal. A Japanese
firm bought the patent rights, and suture materials are now
manufactured in Japan. In addition, this firm uses chitin to
make dressings for burns, surface wounds, and skin-graft donor
sites, which dramatically accelerate healing and reduce pain
compared to standard treatments where the dressings must be
medical uses for chitin include anti-bacterial sponges and
hospital dressings, artificial blood vessels, contact lenses,
tumor inhibition, dental plaque inhibition, and blood cholesterol
control. Household products include sponges, diapers, feminine
napkins, and tampons.
Purification — As a polymer, chitosan's
natural tendency is to form long chains of molecules with positive
charges, which act like hooks. These natural hooks catch organic
materials, such as oils, detergents, and other contaminants suspended
in water. The material then coagulates to form flakes that are
easily filtered out. Filtration companies are using chitin in
clarifiers to help filter particulates and chemicals from water.
Wastewater Treatment — In Japan, chitosan
was first used for wastewater treatment because of its metal-binding
properties. It is also good for cleaning up toxic organic compounds,
such as PCBs.
Dietary Supplements: Chitosan
has properties similar to plant fiber and can significantly bind
fat, acting like a sponge in the digestive tract. It is not digestible
itself and the bound fat leaves via the body without ever entering
powder; nail polish; moisturizers; face, hand, and body creams;
and toothpaste are just a few consumer products that might
Agriculture: Seeds treated
with chitosan are larger and stronger and more resistant to fungal
diseases. Treating seeds with chitin can increase crop yields
by up to 50%.
Chitin is added to commercial feed mixtures containing whey,
a by-product of the cheese industry. Many animals find it hard
to digest the high-lactose whey. But chitin supports the growth
of beneficial microorganisms in the animals' digestive tract
— these bacteria produce enzymes that help the animals digest