Thursday 29 November 2012

Practical Polysaccharides (Part 10 - Last): Chitin-Heparin Bico in Wound Care

Part 10 of the paper by Jacek K. Dutkiewicz of Buckeye Technologies Inc given at this years Insight Conference organised by MTS in Norfolk Virginia. (Click here for Part 1)
Chitin and its simple derivative chitosan are highly crystalline which makes them suitable for making high-tenacity structural materials such as fibers and films.   An interesting discovery was made some time ago [10] and remained practically unknown. It resulted from experimentation with solutions of chitosan and heparin, two oppositely charged polymers.   It was observed that at the interface of these two solutions it was possible to form a liquid film which had fiber forming characteristics (Fig. 17).  Thus prepared filaments were composed with a chitosan core and heparin sheath.  The purpose of that study was to combine bacteriostatic and wound-healing properties of chitosan with blood anticoagulant characteristics of heparin.  Potential medical applications of such materials involved for instance vascular grafts.

Another less known property of chitosan and, in particular, some of its salts involves ostensibly self-contradictory interactions with blood.  Chitosan has good hemostatic properties and this is one of the
reasons for its use in wound dressings.  In this case blood coagulation occurs via sequestration of negatively charged blood cells with polycationic chitosan.  On the other hand, what is not well known is the fact that polycationic chitosan can be used as a coating to neutralize negatively charged surfaces (e.g. of glass or polyester fibers) and thus interfere with the intrinsic coagulation pathway [11].  As a result, undesired formation of blood clots becomes effectively inhibited (Fig. 18).

One could go on quoting examples of existing but less known solutions to various technical problems related to polysaccharides and to a variety of products made therefrom.  Some of these solutions, if used properly, may potentially become uncovered golden nuggets saving time and efforts in research and product development.  The key is to have an effective tool to look for these solutions.  First and foremost though there needs to be an incentive, a strong enough pull based on customer and business needs to do the work and solve a given problem.  Perhaps some of the existing, old solutions became abandoned or forgotten not because they had no technical value but just because the timing was wrong or the customers’ pull was not there yet.

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13. J.Dutkiewicz, L.Judkiewicz,  M.Kucharska, R.Ciszewski: Chitosan Sealant for Vascular Grafts with No Need for Heparinization in Advances in Chitin and Chitosan, eds. C.Brine, P.Standford, J.Zikakis, Elsevier, New York, 1992, p.54.

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