Team:Exeter/Applications

From 2012.igem.org

Polysaccharides have a spectacular range of properties. These properties stem from the relationships between the chemical nature of the sugars within the polysaccharide, their arrangement within the polymer and the arrangement of the polymer itself. Polysaccharides appear in every corner of the natural world and have multiple applications ranging from protection to energy storage.

Not surprisingly humanity has taken advantage of their diversity and by doing so created a huge variety of uses within the medicinal, material and consumable sectors, as shown by the wealth of scientific literature available.

In this section we invite you to take a brief look at what could one day be possible if a system to design and build bespoke polysaccharides existed.

“It is not what we believe to be impossible that holds us back, but merely the limit to our imagination.”

Alex Clowsley, 2012.


	The potential for new applications or improvements to current treatments across the medical world is vast. Several polysaccharides currently show biocompatible and biodegradable properties, making them suitable for both external and internal functions [1]. Chitin and chitosan have already been studied for their effect on blood coagulation, tissue growth and wound healing [2]. They are now used in wound dressings to aid the natural healing process and chitin, because of its strength and flexibility and the fact it decomposes completely over time is used as surgical thread for stitches. We would suggest an improvement to dressing wounds would be to make an equivalent in the form of a gel, this could then be coated over an open/closed wound. A gel would offer the advantage of being able to use an open-window type dressing thus enabling the injury to be clearly visible and the healing process closely observed. Not only could a gel be used over a wound, it could also be used during extensive surgeries internally on tissue. This could potentially massively increase the rate of healing. Hyaluronan is a polysaccharide that is present within joints and as a solution offers an interesting property. It is viscoelastic, at low strain frequencies it has viscous behaviour whilst at high strain frequencies it displays elastic tendencies [3]. These properties are what enable joints to survive on a daily basis with normal use and sudden impacts. We think that future prosthetics would benefit from research within this area and could possibly provide a replacement limb capable of rivalling, mechanically, the natural design. They may even progress to be able to withstand larger amounts of impact force making the possibilities of running faster for longer and jumping higher a possibility. We have synthesized the gene hasA from Streptococcus pyogenes that codes for hyaluronan synthase. The enzyme hyaluronan synthase is responsible for generating hyaluronan from D-glucuronic acid and D-N-acetylglucosamine, linked via alternating β-1,4 and β-1,3 glycosidic bonds. The gene has been submitted to the registry as part BBa_K764022. † Could we go further still? Blood types are distinguished by the presence of their surface polysaccharides [4]. Depending on which antigens are present some patients can only receive donations from their own blood group or other specific blood types according to their rarity. This drastically reduces the list of potential options. In the future we envisage a system where donor blood could be “masked” to display the properties of its intended acceptors blood. This would be achieved by creating a polysaccharide that could bind to the surface of donor blood with one end and via the other display the same properties required for the recipient, thus passing as the host blood type. We believe this would lead to a new Universal Blood Donor Group with the potential of replacing conventional methods.


	Currently polysaccharides can be found in wastewater treatment processes. Chitin has been shown to decontaminate water containing plutonium and mercury, whilst chitosan is able to remove arsenic from contaminated drinking water and petroleum from wastewater [5]. There is also the potential for polysaccharides to be used in the removal of other heavy metals from wastewater [6]. Imagine if you were able to use polysaccharides to at first detect harmful elements within water, obtain a fast signal to say exactly what was present and then also be able to extract all of the contaminant using a polysaccharide removal system! In plants, polysaccharides such as starch are used to store energy obtained via photosynthesis. Scientists have had mixed success when using polysaccharides in the production of solid state proton-conducting polymer batteries and believe a better battery system could be accomplished with a more suitable electrode material [5]. If we could manufacture polysaccharides with specific electrical properties, could it be possible to harness some form of energy and make a fuel cell? And if it were possible could we take it one step further and create mini biological circuits with custom built polysaccharides playing the roles of diodes, resistors and capacitors? Last year Suzanne Lee, {i}, set a challenge; to spin her a bug, align it in a certain direction, grow it around a specific shape and make it hydrophobic. We believe that our project is a step in the right direction to making this a reality. With the ability to create novel polysaccharides and build them with very specific properties, in both physical and electrical, a vast amount of new, unique, and exciting materials could present themselves. One that may be invented could take advantage of Xylomannan found within the Alaskan Beetle, Upis ceramboides. Its anti-freeze ability enables the beetle to resist temperatures below -60°C [7]. A suit which could withstand such extreme temperatures would have many uses, perhaps predominantly in diving and space suits!


	Polysaccharides are present in most foods but not just as the notorious “e-numbers”. They can be used as edible food glues to accomplish many different types of effects from the assembly of food parts (like cakes) to highly decorative pieces of food art. Along with their artistic capabilities polysaccharides also offer themselves to: thickeners, suspension agents, oxidation- and dehydration resistance, and the ability to extend the shelf life of foodstuff [8]. In the future imagine if we could amplify the ability to preserve food... this would have a massive effect on global food shortages. Not only might it be possible to coat, or perhaps even grow, current “perishables” such as fruit and veg but the billion tons worth of food which is wasted every year could find itself ingested instead of buried! With modernised countries overcoming the wasteful attitudes found in people today, the food which is currently produced to sustain the demand could then be exported to nations who still struggle with producing sufficient quantities of food. Cyclodextrin can act as a cholesterol reducing agent removing cholesterol from food products [9]. Could this one day take the form of an elite “diet” pill? It wouldn’t be an alternative to exercise though, were such a tablet to exist, people would still need to keep fit to obtain any muscle! We have synthesized the gene amyA from Bacillus sp 1011,GI:1942571. This codes for cyclodextrin glycosyltransferase which is the enzyme responsible for the enzymatic conversion of starch to the cyclic oligosaccharide cyclodextrin. The gene has been submitted to the registry as part BBa_K764023.†† It has been shown that polysaccharides can not only stimulate the germination of some seeds but also protect plants from specific pathogens and funguses [1]. When extended space flight becomes a reality, consumable lifetime will be a serious issue. Therefore polysaccharide coating could provide a means to supply a space vessel with not only a sufficient amount of long lasting food, but also provisions that are resistant to; water loss, bacterial growth, and mutations from ionising radiation.


	Could it be possible to produce polysaccharides that have specific hydro(phobic/phillic) domains that would self-assemble when introduced to water? We believe that not only could this be possible but multitudes of new, novel and exciting materials, [10], could one day present themselves. The self-healing abilities of certain types of supramolecular elastomers arise due to their intermolecular interactions [10]. We think this could be improved upon using research into polysaccharides, to create a glue, gel or paint like product which could be easily sprayed or coated onto materials which need protecting. These could include covering a vehicle to make it effectively “scratch proof” or, producing a thinner film to cover screens, like those found on smart phones, which come under a constant barrage of attacks daily from keys and coins! Perhaps one day polysaccharides with such “self-healing” abilities could be used in the production of clothes. Possibly this could make them resistant to staining from food, drink and toothpaste but also resilient to rips and tears? Newcastle 2010 iGEM team, {ii}, thought that the glue like polysaccharide levansucrase could be strong enough to be used fixing cracks in cement! Could a modified polysaccharide be embedded into climbing gear to make your very own lizard/spider suit? Still not satisfied? We mentioned earlier, in the medical section, the potential of building upon the uses of polysaccharides that have amazing properties when involved with impacts, but could we go further still? Could we create a material that was so finely woven and had so many layers that it could not only stop a bullet but could also distribute the energy involved so the user felt nothing? If a bullet could be stopped by this type of material could a bomb blast be absorbed too? And what about falling with a broken shoot, could a special sky diving suit be made that rendered parachutes obsolete?

There are endless possibilities in how polysaccharides could be used to help achieve new and exciting applications. These are some of the reasons why we believe our project could make a fundamental difference in not only the world of synthetic biology but science as a whole.

The building blocks to take Science a step further, begins here.

[1] M. Wisniewska et al: Biological properties of Chitosan degradation products: Polish Chitin Society: Monograph XII:149-156:2007.

[2] M. Kucharska et al: Potential use of Chitosan – based material in medicine: Polish Chitin Society: Vol. XV: 169-175:2010.

[3] W. Comper et al: Physiological function of connective tissue polysaccharides: Physiol Rev: Vol. 58: 255-315:1978.

[4] A.Furth: Lipids and Polysaccharides in Biology: Issue 125 of Studies of Biology: ISBN 0713128054.

[5] P. Dutta et al: Chitin and Chitosan: Chemistry, properties and applications: J. Scientific & Ind Res: Vol.63: 20-31:2004.

[6] G. Crini: Recent developments in polysaccharide-based materials used as adsorbents in wastewater treatment: Prog. Polym. Sci: Vol. 30: 38-70: 2005.

[7] K. Walters,Jr. et al: A nonprotein thermal hysteresis-producing Xylomannan antifreeze in the freeze-tolerant Alaskan beetle Upis ceramboides: PNAS: Vol.106 No.48: 20210-20215: 2009.

[8] M. Volpe et al: Polysaccharides as biopolymers for food shelf-life extension: recent patents: Recent Pat. Nutr. Agric: Vol. 2: 129-139: 2010.

[9] L. Alonso et al: Use of β-cyclodextrin to decrease the level of cholesterol in milk fat: J. Dairy Sci: Vol. 92: 863-869: 2009.

[10] T. Aida et al: Functional Supramolecular Polymers: Science: Vol. 335: 813-817: 2012.

†. BBa_K764022

††. BBa_K764023

{i}. You can watch her talk on the TED website

{ii}. Newcastle 2010 iGEM team.

<< Revisit the Concept

Human Practices >>

Website Designed and Built by: Ryan Edginton, James Lynch & Alex Clowsley | Contact Us | Site Map