| Acronym: |
NanoBioSaccharides |
| Priority: |
Priority 3 - NMP (Nanotechnologies and nano-sciences, knowledge-based multifunctional materials and new production processes and devices) |
| Call for proposal reference: |
FP6-2003-NMP-TI-3-Main |
| Duration: |
36 months |
| Start date: |
1st April 2005 |
| Project number: |
013882 |
| Partners number: |
15 |
| Coordinator: |
Westfälische Wilhems-Universität Münster |
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Project summary: New skin out of old shells
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Crab and shrimp shells contain a very valuable polymer, namely chitin, which can be converted into an extremely versatile biopolymer, chitosan, to be applied in many different fields such as agriculture and medicine. It has been shown that plants treated with chitosan become more resistant to diseases, and wound dressings made from chitosan can help wounds and severe burnings to heal without scar formation. However, these precious properties of chitosan are not reliable enough for commercial applications. You would need to use about 40 kg of chitosan per hectare to protect plants from disease! And the almost miraculous healing properties of chitosan were observed in some cases only, while no such effect was seen in most trials. Apparently, the biological properties of chitosan vary from one batch of chitosan to the next, perhaps depending on the source of chitin used. |
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<< Chitosan flakes drying inside green house
Gillet-Mahtani Chitosan plant, Veraval, India |
Chitin is commercially extracted from shrimp shells a waste by-product of the shrimp peeling factories e.g. in Morocco, where most of the European shrimps are peeled. World wide, ca. 75,000 tons of dried shrimp shells are produced annually, and these could easily yield 3,000 tons of chitin. Currently, around 300 tons of chitin are produced each year, and part of this is converted into chitosan by caustic soda treatments.
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Chitin is a very large sugar molecule with a large number of acetic acid molecules attached to it. The soda treatments remove some of this acetic acid from the sugar backbone, converting chitin into chitosan. |
However, depending on the exact conditions of the soda treatments, more or less of the acetic acid molecules are removed, yielding different chitosan molecules, some with still a lot of acetic acid attached, and some with almost no acetic acid left. |
In a previous research project also financially supported by the European Union, the CARAPAX project, researchers from Germany, France, Norway, and Greece teamed up to optimise the processes of chitin extraction and chitosan production so that chitosans with specific and well known amounts of acetic acid attached to the sugar backbone could be produced. These were tested for their ability to protect plants from disease, and it was found that the plant protective activities greatly depended on the acetic acid levels present in the chitosan. Using the most active chitosan, the amount needed for adequate protection could be reduced to ca. 160 grams per hectare, comparable to the amount of chemical fungicides needed. |
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However, even the best chitosan produced so far is not yet as effective as chemical fungicides, so that more research and development is needed before chitosan can be used on a larger scale as an environment-friendly and consumer-safe alternative to chemical plant protectants. But the general concept has been proven right: reliable results can be achieved if a well characterised chitosan is used.
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The NanoBioSaccharides project now wants to apply this same concept to medical applications of chitosans, and it aims at advancing our knowledge one further, possibly decisive step.
When using caustic soda to remove part of the acetic acid, the acetic acid molecules are removed in a random way from the sugar backbone. We now plan to use a biological rather than a chemical process to remove some of the acetic acid molecules. It is known that some micro-organisms contain enzymes called chitin de-acetylases which act like scissors, cutting off acetic acid molecules from chitin. |
We have found that some fungi possess several enzymes like this, and we predict that they will act in somewhat different ways, yielding somewhat different chitosans. It could easily be imagined that one enzyme would remove a single acetic acid molecule at a time, then dissociate from the chitin molecule and subsequently attack at a different site. Such an enzyme would yield a chitosan molecule with a random distribution of acetic acid molecules attached, just as the chemical process. But another enzyme might take off a number of adjacent acetic acid molecules each time it binds to chitin, and such an enzyme would yield a chitosan with a block- or patchwise distribution of acetic acid molecules. Similarly, specific enzymes might yield chitosans with specific patterns of acetic acid residues attached to the sugar backbone. Our prediction is that such chitosan molecules, differing only slightly in the distribution of the acetic acid molecules, will greatly differ in their biological properties. |
In the NanoBioSaccharides project which is financed by the European Union, scientists from universities and commercial companies in Germany, France, Spain, Denmark, Italy, and more recently Thailand and India, will collaborate to test this prediction. We will, therefore, isolate and characterise such enzymes from a number of micro-organisms, and we will use them to generate specific chitosans. These will be analysed in molecular detail concerning the amount and distribution of acetic acid residues. Such extremely well characterised chitosans will then be used in a number of different assays to test their biological properties, and their suitability for a range of medical applications. |
| On the one hand, we will use these chitosans to form nanoparticles (a nanoparticle is a particle with a diameter of ca. 100 nanometer, 1 nm being one millionth of a millimeter: about 1,000 such nanoparticles placed in a row would be needed to reach the thickness of a human hair!). |
Chitosan nanoparticles are known for their ability to overcome biological barriers and facilitate the delivery of complex drugs such as insulin, vaccines, and plasmid DNA. In the present project, we plan to optimize these technologies to further improve the delivery of macromolecules, e.g. insulin, via the nasal, pulmonary, and oral routes instead of via an injection into the blood vessels. |
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Fluorescent nanoparticles crossing the nasal mucosa >
USDC - Nanotechnologies applied to drug delivery Unit |
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Also, the chitosans will of course be used to generate hydrogels to be used as wound dressings. If we use just the right chitosan, these wound dressings should be antiseptic, keeping the wound clean, they should be hygroscopic, keeping the wound moist, and they should exert an organising effect on the underlying tissues, leading to an organised rebuilding of new and totally intact skin layers. |
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More in details
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The NanoBioSaccharides project convenes an interdisciplinary consortium of scientists from academia and industry to develop and exploit nanotechnologies for the generation of knowledge-based, multi-functional, bio-inspired polysaccharides to be used as intelligent, sustainable, environment-friendly, consumer- and patient-safe bio-materials. The project is based on the novel concept of biological decoys acting as functional bio-medical materials. This concept which was recently developed by the core partners of the NanoBioSaccharides project causally links the physico-chemical properties of polysaccharides, in particular of chitosans, to their biological activities. The NanoBioSaccharides project aims at validating this concept which upon verification would generate breakthrough knowledge in the highly promising field of nanobiotechnologies, and which upon implementation would potentially lead to significant transformation in the field of medical bio-materials, drug and gene delivery, and cell and tissue engineering.
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Polysaccharides are by far the most versatile and diverse class of biopolymers, and with an estimated annual production of 10 11-12 tons of cellulose and 10 10-11 tons of chitin alone, they are also by far the most abundant renewable resource available. Owing to their superior structural properties, poly-saccharides have long been used in bulk quantities in the film and fiber, paper and textile industries. However, increasing evidence suggests that polysaccharides also have superior functional properties, being involved e.g. in the non-self recognition in human immune systems and plant disease resistance. Polysaccharides, thus, emerge as the third and so far neglected and unexploited class of information-bearing biopolymers. Their great complexity and diversity and their innate microheterogeneity make analysis and synthesis of polysaccharides extremely demanding, and even the most sophisticated chemical and physical methods are inadequate to fully understand the many roles polysaccharides play in nature. The emerging techniques of nanotechnology, however, promise to allow for the first time analysis and manipulation of single molecules, a conditio-sine-qua-non for the nano-scale understanding and exploitation of polysaccharides. |
Bio-active polysaccharides have been isolated from natural sources to be used in biotechnological applications, but with limited success due to a lack of understanding the molecular basis of their biological activities. A second generation of bio-mimetic polysaccharides was later developed trying to improve their performance in biomedical applications but again, with little commercial success due to a lack of reliability. Based on extensive studies of the structure-function relationships of chitosans, the core proposers of the NanoBioSaccharides project have recently developed the concept of bio-inspired ‘decoy’ polysaccharides to be used as novel plant protectants and medical bio-materials. A decoy is a not a bio-mimetic, but rather a bio-inspired material which only partially resembles a natural structure and which therefore elicits only certain reactions in a cell, tissue, or organism. As the decoy is not identical to the natural structure, it only induces some aspects of the natural reactions, but not others - or it may be more stable and long-lasting, as it is much less rapidely degraded. By tailor-designing a bio-inspired decoy, it will be possible to elicit only those aspects of a given natural reaction that are wanted, with no unwanted side reactions.
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By developing nanotechnologies suitable for polysaccharides, the NanoBioSaccharides project will secure the EU a head start in the emerging and promising field of functional bio-materials. In an exploratory manner, we will initially focus on the polysaccharide chitosan which can be generated from the chitin isolated from shrimp shell wastes of the fishery industries, increasingly broadening our scope to other polysaccharides such as plant pectins, alginates, and animal and human glycosaminoglycans. The project will integrate the whole product chains from the raw materials to the novel, nano-scale modified polysaccharides as well as nanoparticles and nano-structured physical hydrogels prepared from them to be used in biotechnological applications. Again, the project will be strictly focused to bio-medical applications in drug and gene delivery, and in cell and tissue engineering., but will keep an open eye on further applications, e.g. in pharmacology, cosmetics, agriculture, and food sciences. |
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