Applications of Chitin and Chitosan

Applications of Chitin and Chitosan provides an examination of the state of the art, and discusses new applications as well as potential products. It deals almost exclusively with applications. Previous books in the field have devoted less than 30% of their material to commercial or medical uses.

URL: http://www.chipsbooks.com/appchit.htm

Research Project: Chitex

Objective: Functionalising textiles by means of chitin/chitosan for applications in hygiene and care products

Duration: 2003 -2005

The actual trend in the textile sector (woven and non-woven) is to add properties to textiles. This tendency gave birth to the notion of 'functional textiles'. Functionalising textiles (by conventional finishing or by coating) is an activity based on know-how and creates a high added value. This is the reason why the European textile industry is more and more evolving in this direction. Over the last years, many different products have been marketed displaying properties such as anti-odour, anti-bacteria, anti-dust mite or refined thermal comfort. With respect to coatings, the focus is mainly laid on selective barriers applied in technical textiles, sportswear and leisure wear and also to a high degree in medical textiles.

Functionalising textiles is usually done by applying a synthetic active product directly onto the textile or by mixing it as an additive in a coating layer.

The more functional a textile becomes the more it is charged with synthetic products. Since textiles are often in contact with the skin, and since they are often being cleaned or washed, functionalising textiles involves extra health and environmental risks. Companies are more and more compelled by the authorities as well as by several pressure groups to prove the absence of undesired effects. Because of this, a large part of the added value is taken up by testing and certification. Therefore there is an increasing need for natural, biocompatible and biodegradable active products to replace the synthetic ones.

Chitin and its derivate chitosan are natural polymers, produced by insects, crustaceans, and even certain fungi.

Contrary to the existing synthetic polymers, chitin and chitosan are biodegradable and biocompatible. At present, chitosan is already being used in several applications, albeit on a very small scale. Some examples are thickening agents in pharmaceutical and cosmetics formulas (chitosan solutions display already a very high viscosity at a concentration of 2-3%), as a flocculent in water purification plants and breweries (chitosan is strongly sequestrating for metals) and as a filling agent in the paper industry. It is also known that these bi-polymers have anti-microbial and wound-healing properties. Especially these last properties are interesting for textile applications.

The applicability of chitosan in textiles is also supported by its being water soluble (acid pH) and the fact that the molecule possesses different chemical groups which may interact with textile fibres. The project's aim is to systematically examine the large potential offered by chitin and chitosan to textile finishing (directly as well as by means of coating). First of all, we will study the anti-bacterial and anti-fungi properties. The activity of chitosan is mainly determined by its molecular weight and acetylisation degree.

The unique collaboration with Ulg (Université de Liège) gives us access to pure and well-characterised products. It even offers the opportunity to produce specific variants on the basis of the results. In this respect we will be able to unambiguously relate the action of a chitosan to its composition and elaborate formulas (precise concentration and composition) with a specific action in a very cost-effective way.

Textiles that have been finished with chitin / chitosan have many applications in household linen, textile care and hygiene products, sportswear, medical textiles and protective clothing.
During the second biennial of the project, the possibilities of chitosan in high-quality medical textile applications will be examined, such as wound-healing, moisture absorption as well as the possibilities to release certain actively healing molecules thanks to the sequestrating properties of chitosan or by means of a chitosan hydrogel (e.g. growth factors).

Project manager : Tom Meyvis

Eight-week histological analysis on the effect of chitosan on surgically created one-wall intrabony defects in beagle dogs

Abstract

Objective: To evaluate the periodontal tissue regenerative effects of a chitosan/collagen sponge applied to preclinical one-wall intrabony defects surgically created in beagle dogs.

Material and Methods: 44 mm one-wall intrabony defects were surgically created in the bilateral maxillary first and third, and the mandibular second and fourth premolars. The surgical control group received a flap operation only, while the buffer control group was treated afterwards with a phosphate-buffered saline/collagen sponge (CS) and the chitosan group was treated with a chitosan/cs. The subjects were killed 8 weeks after the operation, and a comparative histological examination was performed.

Results: The amount of junctional epithelium migration was 2.30±1.24 mm in the surgical control group, 1.49±1.25 mm in the buffer control group, and 0.26±0.59 mm in the chitosan group. A significant difference was exhibited only between the surgical control and the chitosan group (p<0.05).

Conclusion: The results demonstrate the beneficial effect of the chitosan/cs on the one-wall intrabony defects of beagle dogs. The inhibited apical migration of epithelium and the increase in the amount of new bone and new cementum suggest the potency of chitosan in inducing periodontal tissue regeneration.

Shrimp-based Bandages Save Lives

Unstoppable bleeding is one of the leading causes of death on battlefields. But now, soldiers in Iraq and Afghanistan have a way to reduce bleeding when they're wounded. In "War Bandages," ScienCentral News writes that these new bandages contain chitosan molecules, extracted from shrimp shells. These positively charged chitosan molecules attract negatively charged red blood cells, stopping hemorrhage in one to five minutes. As said one of the co-founders of the Oregon-based company behind these bandages, "You can have a hole in your heart and 60 seconds later it's sealed." The Food and Drug Administration approved these bandages for human usage, but today they are exclusively sold to the Army. With a $90 price tag for a 4-inch-by-4-inch single bandage, would you buy them anyway?

Here are some details about these bandages made of shrimp-based chitosan.
The bandages were developed by HemCon, Inc., which develops and markets technologies to control severe bleeding for traumatic skin and organ injuries. The key ingredient in the shrimp shells is called chitosan. Kenton Gregory, a cardiologist from Providence St. Vincent Medical Center in Portland, Oregon who co-founded HemCon, says unlike the gauze that traditional bandages are made from, chitosan interacts with our blood cells because its molecules carry a positive charge.

"The problem with gauze is that it really has no clotting ability," Gregory explains. "Generally the gauze just saturates, is just saturated with blood, and the bleeding continues. The chitosan has a positive charge. All of our cells, our red blood cells, the outer membranes have negative charges. And the negative charge of the red [blood] cell is attracted to the positive charge of the chitosan. As soon as they touch, the red cell fuses and forms a clot against the chitosan, and that forms a very tight, adherent clot, and a tight adherence to the surface of the wound."

You can see below how the negatively charged red blood cells are attracted by the positively charged chitosan molecules. (Credit: Illustration by Jason Lee, for Popular Science)



This illustration comes from a short story about the HemCon Bandage published by Popular Science in its December 2003 issue, giving the badage one of its Best in Science award. In it, Gregory said "You can have a hole in your heart and 60 seconds later it's sealed."
In "HemCon grows with shrimp tech," published in November 2003, The Business Journal of Portland adds some financial information.

As the [Iraqi] conflict has escalated HemCon has shipped more than 11,000 of the bandages -- made of shrimp-based chitosan -- and has backlog orders totaling 40,000.
The medical device company will log revenue of about $3.5 million in 2003 -- the bulk from military and government allocations -- and is projecting impressive growth to $20 million in 2004 revenue.

It's interesting to notice that this bandage was not invented by HemCon. Instead, the company licensed the technology.

Dr. William Wiesmann, HemCon president and CEO, stressed HemCon is a model outcome of a successful technology transfer. The bandage was developed at the bargain price of $400,000, and it will ultimately bring millions into the state [of Oregon].

The bandage was invented at the Oregon Medical Laser Center, based at Providence St. Vincent Medical Center, through a research grant from the U.S. Army Medical Research and Materiel Command. The chitosan bandage technology was then licensed from Providence Health System to HemCon Inc., founded by Dr. Kenton Gregory.

The research work about how the chitosan dressing on these bandages stops hemorrhage was published by The Journal of Trauma. Here is a link to the abstract of the paper named "Effect of a Chitosan-Based Hemostatic Dressing on Blood Loss and Survival in a Model of Severe Venous Hemorrhage and Hepatic Injury in Swine."

Sources: ScienCentral News, August 27, 2004; Popular Science, December 2003 issue; Robin J. Moody, The Business Journal of Portland, November 14, 2003; The Journal of Trauma, Volume 54, Issue 1, pages 177-182, January 2003

Chitosan: Is It Good for Weight Loss?

The product and what it's marketed for: chitosan is a dietary fiber derived from the shells of shrimp, crabs and other crustaceans. Many companies promote it as a weight-loss tool, a natural "fat-blocker." The fiber is packaged into a pill that, when taken just before eating, is said to bind to fat in your food, causing the grease you ate to be excreted rather than absorbed.

Many brands claim that, in addition to taking off the pounds, chitosan boosts HDL, good cholesterol, while reducing the bad, LDL cholesterol, and decreases the risk of colon cancer. Different companies market pills with different dosages and distinguish their products with different formulations, often adding vitamin C or other compounds that they claim improve chitosan's fat binding ability.

Depending on the formulation, marketers claim the supplement can absorb as much as 12 times its own weight. Some brands are advertised online for as low as $5; others cost $40 or more and most bottles last 1 to 2 months, depending on how many pills are taken at a time and how frequently.

Whats's known: chitosan binds to fatty acids - which are what's left of the fat in your food after your stomach enzymes have broken it down. Theoretically, that fat is then shuttled out of your system attached to the indigestible fiber.

Scientific studies are often cited as proof of chitosan's effectiveness in the promotional literature, but the few studies that have shown chitosan to be effective for weight-loss are "flawed in many ways," said Max Pittler, a researcher in complementary medicine at the Universities of Exeter and Plymouth in the United Kingdom. Pittler worked on a clinical study, which was published in a peer-reviewed journal in 1998, and found the supplement had no effect on weight or cholesterol.

Clinical studies have failed to prove that chitosan actually helps you slim down, but a few have shown that it can moderately curb cholesterol levels, said pharmacologist Richard Ogletree at the University of Mississippi Medical Center in Jackson and the co-author of "The Physicians' and Pharmacists' Guide to the Top Ten Scientifically Proven Natural Products." Ogletree said he wouldn't recommend chitosan to someone looking to lose weight, but if someone was set on taking the supplement, he wouldn't be too discouraging. Unless you are allergic to shellfish, in which case it might spark a reaction, chitosan doesn't seem to have dangerous side effects, and, he added, "most people can use a little decrease in cholesterol."

There have been no clinical studies testing whether different formulations of chitosan are more effective, Ogletree said. Based on its chemistry, vitamin C ought to help it work better. Still, even at its most effective, chitosan will likely do as much to reduce cholesterol as oat bran and other soluble fibers. A more cost-effective approach to heart health would be to eat more oatmeal. And neither option is dramatic enough for those with dangerously high cholesterol.

The Bottom Line: No supplement is likely to ever help you drop pounds if you don't change your eating and exercise habits, experts say.

"It's not easy to lose weight," said Jyni Holland, a dietician at New York University Medical Center. "It requires work and dedication."

The surest way to slim down is to eat fewer calories and do moderate exercise. Holland recommends setting realistic goals, keeping nutritious, low-calorie foods close at hand and using your willpower to stay away from waist-expanding foods such as pizza or potato chips. "If losing weight were easy, no one would be obese."

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