Biopolymer

Biopolymers, PHA, synthesis, recovery, application

1. BIOPOLYMER Neethu Asokan

2. contents Introduction of polymers. Biodegradable polymers. Classification of biodegradable polymers. Polymer Degradation mechanisms a) Bioerosion mechanism. b) Enzymatic or chemical degradation. Synthetic biodegradable polymers. Natural biodegradable polymers. Factors affecting biodegradation of polymers. Applications of biodegradable polymers. Conclusion. References. Neethu Asokan

3. biopolymer The term " polymer " derives from the ancient Greek word polus, meaning "many, much" and meros meaning "parts", and refers to a molecule whose structure is composed of multiple repeating units. The term was coined in 1833 by Jons Jacob Berzelius. Biopolymers are polymers produced by living organisms. Since they are polymers, biopolymers contain monomeric units that are covalently bonded to form larger structures. Neethu Asokan

4. BIOPOLYMERS AS MATERIALS Some biopolymers- such as Polylactic acid (PLA), naturally occurring, and poly-3-hydroxybutyrate (PHB) can be used as plastics, replacing the need for polystyrene or polyethylene based plastics . Some plastics are now referred to as being ' degradable ', ' oxy-degradable ' or ' UV-degradable '. This means that they break down when exposed to light or air, but these plastics are still primarily (as much as 98 per cent) oil-based and are not currently certified as 'biodegradable' under certain international laws . Biopolymers, however, will break down and some are suitable for domestic composting. Neethu Asokan

5. BIODEGRADABLE POLYMERS Biodegradable polymers are defined as polymers comprised of monomers linked to one another through functional groups and have unstable links in the backbone. They are broken down into biologically acceptable molecules that are metabolized and removed from the body via normal metabolic pathways. Based on biodegradability polymers are classified as: 1 . Biodegradable polymers eg : collagen, poly glycolic acid etc., 2 . Non biodegradable polymers eg : poly vinyl chloride, polyethylene etc., Neethu Asokan

6. CHARACTERISTICS OF AN IDEAL POLYMER Should be versatile and possess a wide range of mechanical, physical, chemical properties. Should be non-toxic and have good mechanical strength and should be easily administered. Should be inexpensive Should be easy to fabricate. Should be inert to host tissue and compatible with environment. Neethu Asokan

7. Classification of biodegradable polymers BIOPOLYMER AGROPOLYMER Neethu Asokan

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9. Polymer Degradation Polymer degradation is a change in the properties The term 'biodegradation' is limited to the description of chemical processes ‘ Bioerosion' may be restricted to refer to physical processes that result in weight loss of a polymer device. The bioerosion of polymers is basically of two types :- 1) Bulk erosion 2) Surface erosion Neethu Asokan

10. Types of bioerosion 1) Bulk erosion Degradation takes place throughout the whole of the sample. Ingress of water is faster than the rate of degradation Eg : Polylactic acid (PLA) Polyglycolic acid (PGA) 2) Surface erosion Sample is eroded from the surface. Mass loss is faster than the ingress of water into the bulk. Eg: Polyanhydrides , Polyorthoesters Neethu Asokan

11. Chemical or enzymatic degradation – It is mediated by water, enzymes, microorganisms. TRANSFORMATION OF SIDE CHAINS CLEAVAGE OF CROSSLINKS CLEAVAGE OF BACKBONE Neethu Asokan

12. CLASSIFICATION OF BIODEGRADABLE POLYMERS BASED ON THE SOURCE 1) Synthetic biodegradable polymers: eg: Aliphatic poly(esters) Polyanhydrides Polyphosphazenes polyaminoacids Poly orthoesters etc., 2) Natural biodegradable polymers: eg: Albumin Collagen Dextran Gelatin Pectin, starch etc., Neethu Asokan

13. Synthetic biodegradable polymers 1) Aliphatic poly(esters) These are prepared by polymerization of cyclic ester. Aliphatic polyesters include: a) POLY (GLYCOLIC ACID) b) POLY (LACTIC ACID) c)POLY (CAPROLACTONE) POLY (GLYCOLIC ACID) ---(--O—C-CH 2 ---) n POLY (LACTIC ACID) --(--O---C—CH---) n Neethu Asokan

14. Some Biodegradable Polymers Starch Cellulose PLA PHB PCL PHA PA Neethu Asokan

15. Polylactic acid Poly(lactic acid) or polylactide (PLA) is a thermoplastic aliphatic polyester commonly derived from renewable resources, such as corn starch (in the United States), tapioca products (roots, chips or starch mostly in Asia) or sugarcanes (in the rest of world). It can biodegrade under certain conditions, such as the presence of oxygen, and is difficult to recycle. Neethu Asokan

16. POLYGLYCOLIC ACID Biodegradable, thermoplastic polymer and the simplest linear, aliphatic polyester. It is a tough fibre-forming polymer. Due to its hydrolytic instability its use has been limited. It has a glass transition elevated degree of temperature between 35-40ºC., crystallinity, around 45ºC. Degraded by hydrolysis, and broken down by certain enzymes. Applications Used to deliver drugs in the form of microspheres, implants etc., Examples of drugs delivered include steroid hormones, antibiotics, anti cancer agents etc., Neethu Asokan

17. POLY LACTIC ACID (PLA) Neethu Asokan

18. Polylactic acid Neethu Asokan

19. POLYLACTIC ACID (PLA): BIODEGRATABILITY PLA is considered both as biodegradable and as biocompatible in contact with living tissues PLA can be degraded by abiotic degradation . During the biodegradation process, and only in a second step, the enzymes degrade the residual oligomers till final mineralization (biotic degradation). As long as the basic monomers (lactic acid) are produced from renewable resources (carbohydrates) by fermentation, PLA complies with the rising worldwide concept of sustainable development and is classified as an environmentally friendly material. Neethu Asokan

20. applications Biomedical : Sutures, dialysis media and drug delivery devices. The total degradation time of PLA is a few years. It is also being evaluated as a material for tissue engineering. Bioplastic: Useful for producing loose-fill packaging, compost bags, food packaging, and disposable tableware. In the form of fibers and non-woven textiles, PLA also has many potential uses, for example as upholstery, disposable garments, feminine hygiene products, and diapers. Neethu Asokan

21. Due to PLA's relatively low glass transition temperature, PLA cups cannot hold hot liquids. However, much research is devoted to developing a heat resistant PLA Mulch film made of polylactic acid (PLA)-blend bio-flex Biodegradable cups at a restaurant Neethu Asokan

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23. Bioplastics from microorganisms Benefits 100 % biodegradable Produced from natural, renewable resources Able to be recycled, composted or burned without producing toxic byproducts Degradable polymers that are naturally degraded by the action of microorganisms such as bacteria, fungi and algae Neethu Asokan

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26. IMPORTANCE 2003- north america 107 billion pounds of synthetic plastics produced from petroleum take >50 years to degrade improper disposal and failure to recycle overflowing landfills Neethu Asokan

27. Polyhydroxyalkanoates (PHAs) Polyesters accumulated inside microbial cells as carbon & energy source storage Ojumu et al., 2004 Neethu Asokan

28. Polyhydroxyalkanoates (PHAs) Produced under conditions of: Low limiting nutrients (P, S, N, O) Excess carbon 2 different types: Short-chain-length 3-5 Carbons Medium-chain-length 6-14 Carbons ~250 different bacteria have been found to produce some form of PHAs Neethu Asokan

29. Polyhydroxybutyrate (PHB) Short-chain-length PHA Produced in activated sludge Found in Alcaligenes eutrophus Accumulated intracellularly as granules (>80% cell dry weight) Lee et al., 1996 Neethu Asokan

30. PHB Biosynthesis Ojumu et al., 2004 Neethu Asokan

31. PHB: polyhydroxybutyrate Intracellular microbial plastic first found in Bacillus megaterium 80 different types of PHAs formed from 3-hydroxyalkanoate acid monomers 3-14 carbons in length Energy store when nutrient is limited Alcaligenes eutrophus to produce PHB Polymer had low thermal stability and brittle Addition of propionate to culture produced P (3HB-co-3HV) and polymer was flexible and tough HB: hydroxybutyrate HV: hydroxyvalerate Marketed as BIOPOL TM used to make films, coated paper, compost bags, disposable foodwares , bottles . COST is still HIGHER than chemically synthesized polymers Propylene: 1$/kg PHVB: 3-5$/kg Neethu Asokan

32. Recovery of PHAs from Cells PHA producing microorganisms stained with Sudan black or Nile blue Cells separated out by centrifugation or filtration PHA is recovered using solvents (chloroform) to break cell wall & extract polymer Purification of polymer Neethu Asokan

33. Bioplastic Properties Some are stiff and brittle Crystalline structure  rigidity Some are rubbery and moldable Properties may be manipulated by blending polymers or genetic modifications Degrades at 185°C Moisture resistant, water insoluble, optically pure, impermeable to oxygen. Must maintain stability during manufacture and use but degrade rapidly when disposed of or recycled Neethu Asokan

34. Biodegradation Fastest in anaerobic sewage and slowest in seawater Depends on temperature, light, moisture, exposed surface area, pH and microbial activity Degrading microbes colonize polymer surface & secrete PHA depolymerases PHA  CO 2 + H 2 O (aerobically) PHA  CO 2 + H 2 O + CH 4 (anaerobically) Neethu Asokan

35. Biodegradation by PHA depolymerases Neethu Asokan

36. NATURAL POLYMERS These are the polymers obtained from natural resources, and are generally non-toxic . Natural polymers are formed in nature during the growth cycles of all organisms. NATURAL POLYMERS PROTEINS Polysaccharides Eg: COLLAGEN ALBUMIN FIBRIN Eg : DEXTRAN CHITOSAN STARCH ADVANTAGES : Readily & Abundantly Available . Comparatively Inexpensive. Non toxic products. Can be modified to get semi synthetic forms . Neethu Asokan

37. factors affecting biodegradation of polymers Morphological factors Shape & size Variation of diffusion coefficient and mechanical stresses Chemical factors Chemical structure & composition Presence of ionic group and configuration structure Molecular weight and presence of low molecular weight compounds Physical factors Processing condition Sterilization process Neethu Asokan

38. current trends in biopolymer This study on biopolymers market estimates the global demand for biopolymers and market value for 2012 and projects the expected demand and market value of the same by 2018. As a part of quantitative analysis, the study segments the global market by type, application and geography with current market estimation and forecast till 2018. The segmentation by type includes bio-PET, bio-PE, PLA, PHA, bio-PBS, starch blends, and regenerated cellulose; while on the basis of its application the segmentation includes packaging, bottles, fibers, agriculture, automotive, injection molding and others. Neethu Asokan

39. Applications of biodegradable polymers Biodegradable polymer for ocular, tissue engineering, vascular, orthopedic, skin adhesive & surgical glues. Bio degradable drug system for therapeutic agents such as anti tumor, anti-inflammatory agent. Polymeric materials are used in and on soil to improve aeration, and promote plant growth and health. Many biomaterials, especially heart valve replacements and blood vessels, are made of polymers like Dacron, Teflon and polyurethane. Neethu Asokan

40. Applications for Bioplastics, Biopolymers AGRICULTURE Neethu Asokan

41. Advantages of bioplastics Less energy requriment Low CO 2 emission Low green house gas emission Low water consumption Neethu Asokan

42. Advantages of biopolymers Localized delivery of drug Sustained delivery of drug Stabilization of drug Decrease in dosing frequency Reduce side effects Improved patient compliance Controllable degradation rate Neethu Asokan

43. Disadvantage Bioplastics don't always readily decompose. Some need relatively high temperatures and can still take many years to break down. Even then, they may leave behind toxic residues. Bioplastics are made from plants such as corn and maize, so land that could be used to grow food for the world is being used to "grow plastic" instead. Some bioplastics, such as PLA, are made from genetically modified corn. Bioplastics cannot be easily recycled. To most people, PLA looks very similar to PET but, if the two are mixed up in a recycling bin, the whole collection becomes impossible to recycle. Neethu Asokan

44. Numerous synthetic biodegradable polymers are available and still being developed for sustained and targeted drug delivery applications. Biodegradable polymers have proven their potential for the development of new, advanced and efficient DDS and capable of delivering a wide range of bioactive materials. However, only few have entered the market since many drugs faces the problem of sensitivity to heat, shear forces and interaction between polymers. These problems can be overcome by fully understanding the degradation mechanism to adjust the release profile.   Conclusion Neethu Asokan

45. REFERENCES Biotechnology/ U.Sathyanarayana. A text book of biotechnology/R.C.Dubey & Maheshwari. Biodegradable polymers.ppt Bioplastic.1.ppt Recent Developments in Biopolymers/Vicki Flaris , Gurpreet Singh(2009). Biopolymers in Medical Applications: Senthil S. Kumar. www.bioplastics24.com Neethu Asokan

46. Thank you Neethu Asokan