M.PHARMA 1ST SEMESTER SEMINAR ON BIODEGRADABLE POLYMER

1. PRESENTEDBY-
PRIYADARSHISANJIB SAHU
ROLL NO.-021M.Pharm 023

2. CONTENTS
 Introduction
 Polymer classification
 Pharmaceutical polymers
 Biodegradable polymer
 Mechanism of bio-degradation
 Classes of bio-degradable polymer
 Some biodegradable polymer investigated for CDDS
 Factor affecting bio-degradation
 Types of polymer DDS
 Novel mucoadhesive polymer
 Mechanism of mucoadhesion
 Ideal characteristics of bio-degradable polymer
 Advantages of Bio-degradable polymer
 Polymer in pharmaceutical application
 Future trends
 Conclusion
 Reference

3. INTRODUCTION
 POLYMER – Polymer are large or macromolecule containing several small repeating units.
These are formed from small macromolecules called monomers through a process known
as polymerization .
 BIO-DEGRADABLE POLYMER- Polymer which degrade in biological fluid when incorporated in drug
delivery system and results in the release of dissolved or dispersed drugs are called biodegradable
polymer.
 Polymers have found applications in diverse biomedical fields such as drug delivering
systems,developing scaffolds in tissue engineering, implantation of medical devices and artificial
organs, prosthesis, ophthalmology, dentistry, bone repair, and many othermedical fields

4. PHARMACEUTICAL POLYMERS
An ideal polymer for pharmaceutical application should serve
the following requirements-
• It must be biocompatible and degradable
• The degradation products should be nontoxic and should not
create an inflammatory response.
• Degradation should occur within a reasonable period of time
as required by application.
• Based on need of certain application , the polymer should
demonstrate versatile mechanical propertise.;eg stent coating
required polymers to be elastomeric and microsphere
processing require them to have high glass transition
temperature.

5. BIODEGRADABLE POLYMER
 Polymers which degradable in biological fluids when incorporated in DDS and result in the release of
Dissolved or dispersed drug are called biodegradable polymer.
 They are used as they offer advantages like DDS is not required to be removed from the body as it
degrades in the body and the products of degradation are natural and biocompatible thus minimizeing
the concern of toxicity.
 Biodegradable polymer can be used in contraceptives; implants ,injection which are capable of
constantly releasing the contraceptive for up to one year, and in anti-cancer DDS that help in
achieving specific drug concentration at the site of cancer.
 Three basic aprochess govern the design of drug delivery system containing custom synthesized bio-
degradable polymers-
I. Erosion of polymer surface with associated release of physically entrapped drug
II. Cleavage of covalent bond between polymer and drug occurring in two polymer bulk followed by
diffusional drug loss.
III. Diffusion controlled release of physically entrapped drug , with bio-absorption of the polymer delayed
until after drug deplition.

6. Strategies for which DDS is dependent on polymer degradation may be separated into
5 sub-class bellow:

7. MECHANISM OF BIODEGRADABLE
POLYMERS

8. 1)ENZYMATIC DEGRADATION:
Mechanism I- Cleavage of crosslinks
Mechanism II- Transformation of side
chain
Mechanism III-Cleavage of back bone
Exact mechanism is not known but may
be due to lysis of long polymer chain by
attaching to it.

9. HYDROLYSIS :
Breakdown of polymer by water by cleaving long chain into monomeric
units. This is done by two methods
I) Bulk erosion –
-homogeneous erosion.
-degradation takes place throughout the whole sample.
-water intake is faster than the rate of degradation. Eg;
polylactic acid (PLA) ,polyglycolic acid (PGA)
II) Surface erosion –
-heterogeneous erosion.
-Sample is eroded from the surface.
- polymer degradation is much faster than water intake.
polyanhydrides,polyorthoesters.

10. CLASSES OF BIODEGRADABLE POLYMER
Bio-degradable polymer may be classified based on mechanism of release of drug entrapped in it;
1. Slow dissolution and erosion by hydrolysis.
2. Water insoluble polymer undergoing hydrolysis ,ionization, protonation of group without
undergoing back-bone cleavage.
3. Water insoluble polymer degrade to water soluble products by backbone cleavage.
 Polymer which function by slow-dissolution are not strictly-bio-degradable.
However , some are undergoes slow dissolution by
1. Ionization of carboxylic acid function(enteric coating matarials)
2. Protonation of amine function(cellulose acitate)
3. Hydrolysis of hydrophobic side chain (partly esterified co-polymer of methyl vinyl ether)

11. BIO-DEGRADABLE POLYMERS INVESTIGATED
FOR CONTROLLED DRUG DELIVERY
Lactide polymer
Poly anhydrides
Poly-caprolactones
Poly-orthoester
Poly-phosphazenes
Pseudo poly amino acid
Natural polymer

12. 1. LACTIDE/GLYCOLIDE POLYMER-
Most widely investigated biodegradable polymer based on lactic acid and glycolic acid.
Bio-compatible ,predictable biodegradation kimetics,
Properties –
Crystalinity and water uptake are key factor in determining rate of in vivo degradation .
Steriochemistry and polymer composition influence crystallinity .
The racemic poly dl lactide , dl-polylactic acid are less crystalline and lower melting than
stereo regular polymer.
Lactide/glycolide show wide range of hydrophilicity which makes them versatile in
designing controlled release system.
Solubility of these dependent on type & composition of monomer.d ,l and dl lactide and co-
polymer containing less than 50% glycolic acid show solubility in organic solvents like ethyl
acetate,doxane.
Lactide composition involving inter-locking sement of poly has bees reported.

13. BIO-DEGRADATION ;
Aliphatic plyesters undergoes bio-degradation by bulk erosion.
These chain are cleaved by hydrolysis to monomeric units and are eliminated from body through
kreb’s cycle ,primarily as CO2 in urin.
Roll of enzymes are unclear in these process.
LACTIDE BASED DRUG DELIVERY:
Microparticles ,implants,fibers.
Microsphere and microcapsule are prepared by these method-1)solvent evaporation
2)phase separation
3)fluidized bed coating
POLYMERS Approx. time for bio-degradation(months)
Poly(l-lactide) 18-24
Poly(dl-lactide) 12-16
Poly(glycolide) 2-4
50:50(dl-lactide-co-glycolide) 2
85:15(dl-lactide-co-glycolide) 5
90:10(dl-lactide-co-caprolactone) 2

14. Many lactide based drug delivery system containing several drugs have been studied widely
eg;steroid hormone, antibiotic, narcotic antagonist,anticancer.
2.POLY-ANHYDRIDES-
These are investgated to introduce polymeric system which can degrade only from surface to
maximize control over release process.
The drug incorporated matrix were formulated either by compression or by injection molding,drug
sieved to 90-250 micron was mixed with the polymer and pressed into circular dicsat 30 kpsi at
5degree .
The poly-anhydride degrade more rapidly in basic media than in acidic eg;
biscarboxyphenoxypropen polymer degrade in 3 years at pH 7.4 while it degrade in just 100days
in 10.0pH .
Aliphatic aromatic homopolyanhydrides of structure “(OOC-C6H4-O(CH2)x-CO)n
n=1 to 10 was found to disply a zero order hydrolytics degradation profile, with time period of
degradation between 2 – 10 weeks.
Rate of degradation is a function of length of aliphatic chain.

15. Incorporation and release from polyanhydrides matrix of a no. of drugs have been studied eg.
CARMUSTINE has been incorporated into polycarboxyphenoxyacetic acid –sebacic acid 20:80
matrix by 2method;
I. By triturating dry powder polymer and the drug , then compress in a carver press.(72 hr
release profile)
II. By dissolving the polymer and the drug in methylene chloride and than evapourating the
solvent. (twice from method one)
As evaluated by mutation assay the degradation products of polymer were non-mutagenic,non-
cytotoxic .
3.POLY-CAPROLACTONE (PCL) AND ITS CO-POLYMER:
This homopolymer degrade very slowly and may be used in DDS that are designed to last for
more than a year .
Capable of forming blends with various polymer like ; lactic acid ,glycolic acid etc.
These derivatives and homopolymer shows high permeability to drugs and are non-toxic.

16.  PROPERTIES;
Semicrystalline polymer having melting point of 59-64 degrees depending upon crystalline size.
Low glass transition temp. Tg= -60
These are soluble in THF ,chioroform,methyle
chloride,benzene,toluene,cyclohexanone,dihydropyran in room temperature.
It is pourly soluble in acetone, acetonitrile and insoluble in alcohol,petroleum ether diethyle
ether.
CO-polymer of caprolactone-
Polyethylene glycol,ethylene oxide,polystyrene,diisocyanates,chloroprene,THF, dilactide,
diglycolide.
Co-polymer have been prepared from oligomers of PCL; a variety of polyester-urethanes have
been synthesized from hydroxy terminated PCL.
Graft-polymer with acrylic acid , acrylonitrile & styrene are prepared from PCL as the
backbone polymer.

17. PCL also show exceptional ability to form blends with many polymers; the permeability of
blends of PCL with many polymer like cellulose propionate, polylactic acid have been studied
and shown to be usefull for manipulating the rate of release of drug from microcapsule .
Blending PCL with lactide-glycolide copolymer has been shown to be usefull method of
modifying the rate of bio-degradation of composite.
BIO-DEGRADATION-
 Degradation of PCL films & rods implanted subdermally in experimental animals was shown
to begin with random hydrolytics chain separation of ester linkage of polymer at rate almost
shown in vitro.
 Second phase of polymer characterized by decrease in rate of chain separation and the onset of
weight loss due to
i. Diffusion of small mol. Wt and polymer produced during first phase.
ii. Break-up of polymer mass to produce smaller particles with an increased probability of
phagocytosis.
 Degradation is due to presence of an enzyme dilactone.

18. 4.POLYORTHOESTERS-
Polyorthoester are one of polymer that contain acid laible linkage in their backbone which
facilitates manipulation of hydrolysis rate by means of acid or basic excipients physically
incorporated in matrix .
Hydrolysis of such polymer can predominantly confined to outer surface and resultant surface
erosion allows excellent control of release kinetics of incorporated therapeutic agent.
Hydrolysis of these polymer regenerate di-ol, and -butyrolactone ,which rapidly hydrolized
to ὠ-hydroxy butyric acid.
They are sensitive to acid i.e. degrade rapidly whereas remain stable in basic .
Therefore acid and basic excipient are used to enhance the rate and stabilize the interior of
DDS respectively.
So, this results in excipient selection; as short-life DDS with rapid surface erosion use acid
where as long term DDS use basic one.
Implants and oral DDS can be fabricated using these polymer.

19. 5.POLYPHOSPHAZENES:
The polymer are madeup of long chain of alternating phosphorus and nitrogen atoms.each
phosphorus atoms has two side group attached to it.
Polyphosphazene are synthesized by reaction of poly dichloro phosphazine with organic
nucleophiles such as alkoxides ,aryloxide or amines.
The side chain functionalitescan be modified to obtain a wide rangeof properties including water
solubility and degradability.
Based on nature of side group these are of many type-
Hydrophobic
Hydrophilic
Insoluble but surface-active--designed to be inert but elicit surface active character to make it
bio-responsive.
Insoluble biodegradable polyphosphazine.– have bio-compatible backbone which metabolized by
facile hydrolysis to phosphates and ammonia,if side group (R) is also bio-compatible ,then the
polyphosphazine derivativeshave very high potential in biomedical application.

20. Attachment of hydrophobic and hydrophilic side group to the phosphazene polymer chain provides
amphiphilic character to polymer .
Some other polyphosphazene are act as hydrogel , water soluble and bioactive.
HYDROGEL:
 This characteristics appear to be interesting candidate for use as intraocular lenses ,soft tissue
prosthesis or hydrophilic coating for biomedical devices.
Eg. MEEP- poly{bis(methoxy ethoxy ethoxy )-phosphazene},
Bio compatible and lesstoxic, they can be incorporated in formulation of parenteral,
WATER-SOLUBLE ,BIOACTIVE POLYPHOSPHAZENE-
IT have been investigated as plasma expander in addition .
Specific polymer with pendent imidazolyl unit have been studied as carrier macromolecules for
heme and other iron porphyrins.

21. 6.COLLAGEN-
Collagen is the most widely found protein in mammals and is the major provider of strength to
tissue
Utilization is too high ; it not only has been explored for used in various types of surgery,
cosmetics DDS,but also in bioprosthetics implants and tissue engineering of multiple organs as
well.
Poor dimensional stability,variability in drug release kinetics make its limited.
Majorly used in ocular drug delivery system.
7.ALBUMIN-
Its a major plasma protein components.
It accounts for 55% of total protein in human plasma.
It used to design particulate drug delivery system.
Albumin microsphere are used to deliver drugs like insulin,sulfadiazine,5-fluorouracil.
It mainly used in chemotherapy to achieve high local drug concentration for relatively longer
time.

22. 8.DEXTRAN-
Complex branched polysacharidesmade up of many glucose molecules.
It consist of alfa-D-1,6-GLUCAN with side chains linked to the backbone of polymer.
Used for colonic delivery of drug in form of gels
9.GELATIN-
It’s a mixture of peptide and proteins produced by partial hydrolysis of collagen, extracted from
the boiled bones,connective tissue,organs. Gelatin is an irreversible hydrolyzed from of collagen,
physicochemical properties depends on the sources of collagen,extracted method and thermal
degradation .
Applicable-employed as coating material.
-gelatin micropellets are used for oral controlled delivery of drugs.

23. FACTOR AFECTING BIODEGRATION OF POLYMER
Morphological factor- shape & size
-variation of diffusion coefficient and mechanical stresses.
Chemical factor- chemical structure & composition
-presence of ionic group and configuration structure.
-molecular weight and presence of low molecular weight
compounds
 physical factor- processing condition
-sterilization process

24. TYPES OF POLYMER DRUG DELIVERY
SYSTEM
Polymers for Drug Delivery in Tissue Engineering-
polymer scaffolds specifically designed to direct tissue growth. growth. The cell transplantation
method is one of the most commonly used in cartilage and bone formation.
Polymer matrices both natural and synthetic can play a vital role in the delivery of protein
growth factors and cytokines to aid angiogenesis and tissue construction procedures.
careful selection of the polymer and the processing method, controlled‐release matrices,
incorporating proteins and growth factors that induce and enhance tissue growth can be
produced.
future use of gene therapy as a way of regenerating tissue is an exciting area, and despite still
being in its infancy, it may yet provide a solution to the challenge of delivering drugs and
proteins more effectively in all areas of medicine.

25. Poly (lactic‐co‐glycolic acid) Microspheres-
 microsphere refers to a small sphere with a porous inner matrix and variable surface from smooth
and porous to irregular and nonporous; drug when encapsulated is dispersed throughout the inner
matrix.
 The size range of microspheres is typically 1 to 500 μm in diameter.
 Their application as drug delivery vehicles has risen in line with the expanding biotechnology
sector and the promise of new drugs discovered in the wake of the human genome project and
proteomics.
Polymeric Nanoparticles as Drug Carriers-
 Certain chemical entities are either rapidly degraded and/or metabolized after administration
(peptides,proteins, and nucleic acids); This is the reason the idea that nanotechnologies may be
employed to modify or even to control the drug distribution at the tissue,cellular, or sub cellular
levels has emerged.
 for drug targeting are polymerbased nanoparticles, which have been developed since the early
1980s, when progress in polymer chemistry allowed the design of biodegradable and biocompatible
materials.
 nanoparticles are colloidal systems with a size 7 to 70 times smaller than the red cells.

26. They may be administered intravenously without any risk of embolization.
Depending on the method used in the preparation of nanoparticles, either nanospheres or
nanocapsules can be obtained.
Nanospheres are matrix systems in which the drug is dispersed within the polymer
throughout the particle.
Nanocapsules are vesicular systems, which are formed by a drugcontaining liquid core
(aqueous or lipophilic) surrounded by a single polymeric membrane.
Polymeric Micelles as Pharmaceutical Carriers-
They are stable
both in vitro and in vivo, can be loaded with a wide variety of poorly soluble pharmaceutical
agents,effectively accumulate in pathological body areas with compromised vasculature
(infarcts, tumors), and can be targeted by attaching various specific ligands to their surface.
It appears that micellar carriers have a promising future.

27. Polymeric Vesicles-
Polymeric vesicles may be fabricated from a variety of macromolecular amphiphile architectures,
which include: block copolymers, random graft copolymers, and polymers bearing hydrophobic
low‐molecular‐weight pendant or terminal groups.
These tough particles, which reside in the nanometre and micrometer size domains,may be used
for drug targeting, the preparation of responsive release systems, and other drug delivery
applications.

28. NOVEL MUCOADHESIVE POLYMERS
BIOADHESION- This can be defind as adhesion between two matarials ,one of them is biological in
nature , are held together by interfacial forces.
MUCOADHESION- Adhesion of polymer to mucosal membrane.
The development of NDDS has been made possible by the various compatible polymers to modify
the release pattern of drug.
use of acrylate polymers for the development of mucoadhesive formulations have increased
many‐fold, various authors have investigated the mucoadhesive properties of different polymers
with varying molecular architecture.
The various mucoadhesive polymers used for the development of buccal delivery systems include
cyanoacrylates, polyacrylic acid, sodium carboxymethylcellulose, hyaluronic acid,
hydroxypropylcellulose, polycarbophil, chitosan and gellan.

29. Lectins-
Lectins are proteins which have the ability to reversibly bind with specific sugar /
carbohydrate residues and are found in both animal and plant.
Lectins extracted from legumes have been widely explored for targeted delivery systems.
In addition to its capability to bind to the intestinal and alveolar epithelium and hence could
be used to design oral and aerosol delivery systems.
Thiolated polymers-
These are the special class of multifunctional polymers called thiomers which are modified
existing polymers by the addition of thiol group. These are hydrophilic macromolecules
exhibiting free thiol groups on the polymeric backbone.
Thiomers are capable of forming intra‐ and interchain disulphide bonds within the polymeric
network leading to strongly improved cohesive properties and stability of drug delivery
systems such as matrix tablets.

30. Various thiolated polymers include chitosan–iminothiolane, poly(acrylic acid)–cysteine,
poly(acrylic acid)–homocysteine, chitosan–thioglycolic acid, chitosan–thioethylamidine,
alginate–cysteine, poly(methacrylic acid)–cysteine and sodium carboxymethylcellulose–
cysteine.
Poloxomer-
Poloxomer gels are show phase transitions from liquids to mucoadhesive gels at body
temperature and will therefore allow in‐situ gelation at the site of interest.

31. MECHANISMS OF MUCOADHESION
The mucoadhesive must spread over the substrate to initiate close contact and increase surface
contact, promoting the diffusion of its chains within the mucus.
Attraction and repulsion forces arise and, for a mucoadhesive to be successful, the attraction
forces must dominate.
The mechanism of mucoadhesion is generally divided in two steps, the contact stage and the
consolidation stage.

32. IDEAL CHARACTERISTICS OF BIODEGRADABLE
POLYMER
They should be bio-compatible
They should be bio-absorbable
(degradabilityprofile,reabsorption of degradation products)
They should be bi-functional(physical,mechanical,biological)
They should be stable (processing,sterilization,storage)
Its shown that increase in molecular weight of polymer
viscocity of its solution also increases.

33. ADVANTAGES OF BIODEGRADABLE
POLYMER
Localized delivery of drug
Sustained delivery of drug
Stabilization of drug
Decrease in dosing frequency
Reduces side-effects
Improved patient compliance
Controllable degradation rate
Improved therapeutic activity with alterd drug release- the therapeutic activity
increase as the release of drugs is maintained within a desired therapeutic range
eg. PROCARDIA-XL (SINGLE DAY DRUG RELEASE)
LUPRON depot form(AS LONG AS 5 YEARS)

34. POLYMERS IN PHARMACEUTICAL
APPLICATION
Water‐Soluble Synthetic Polymers-
 Poly (acrylic acid)- Cosmetic, pharmaceuticals,immobilization of cationic drugs, base for Carbopol
polymers.
 Poly (ethylene oxide) -Coagulant, flocculent, very high molecular‐weight up to a few millions,
swelling agent.
 Poly (ethylene glycol)- Mw <10,000; liquid (Mw<1000) and wax (Mw >1000), plasticizer, base for
suppositories.
 Poly (vinyl pyrrolidone)- Used to make betadine (iodine complex of PVP) with less toxicity than
iodine,plasma replacement, tablet granulation.
 Poly (vinyl alcohol) -Water‐soluble packaging, tabletbinder, tablet coating.

35. Cellulose‐Based Polymers-
 Ethyl cellulose Insoluble but dispersible in water,aqueous coating system for sustained release
applications.
 Carboxymethyl cellulose Super disintegrant, emulsion stabilizer.
 Hydroxyethyl and hydroxypropyl celluloses Soluble in water and in alcohol for tablet coating.
 Hydroxypropyl methyl cellulose Binder for tablet matrix and tablet coating, gelatin alternative
as capsule material.
Hydrocolloids-
 Alginic acid Oral and topical pharmaceutical products; thickening and suspending agent in a
variety of pastes, creams, and gels, as well as a stabilizing agent for oil‐in‐water emulsions;
binder and disintegrants.
 Carrageenan Modified release, viscosifier
 Chitosan Cosmetics and controlled drug delivery applications, mucoadhesive dosage forms,
rapid release dosage forms.

36. Water‐Insoluble Biodegradable Polymers-
 (Lactide‐co‐glycolide) polymers Microparticle– nanoparticle for protein delivery.
Starch‐Based Polymers-
 Starch Glidant, a diluent in tablets and capsules, a disintegrant in tablets and capsules, a
tablet binder.
Plastics and Rubbers-
 Polyisobutylene Pressure sensitive adhesives for transdermal delivery.
 Polycyanoacrylate Biodegradable tissue adhesives in surgery, a drug carrier in nano‐ and
microparticles.
 Polyethylene Transdermal patch backing for drug in adhesive design, wrap, packaging,
containers.
 Poly (methyl methacrylate) Hard contact lenses.
 Poly (hydroxyethyl methacrylate) Soft contact lenses.

37.  Prolong drug availability if medicines are formulated as Hydrogels or microparticles.
 Favourably alter bio distribution, if formulated into dense nanoparticles.
 Enable hydrophobic drug administration if formulated as micelles.
 Transport a drug to its usually inaccessible site of action if formulated as gene
medicines.
 Make drugs available in response to stimuli.

38. FUTURE TRENDS
Natural polymer has numerous advantages over synthetic ones as being readily
available relatively inexpensive, natural products of living organisms, possibilities of
chemical modifications.
The most exciting opportunities in polymer drug delivery lie in the arena of
responsive delivery systems, with which it will be possible to deliver in response to a
measured blood level or to deliver a drug precisely to a targeted site.
Much of the development of novel materials in controlled drug delivery is focusing
on the preparation and use of these responsive polymers with specifically designed
macroscopic and microscopic structural and chemical features.

39. Such systems include:
Copolymers with desirable hydrophilic/hydrophobic interactions.
Complexation networks responding via hydrogen or ionic bonding.
Polymers as nanoparticles for immobilization of enzymes, drugs, peptides, or other
biological agents.
New biodegradable polymers.
New blends of hydrocolloids and carbohydratebased polymers.
o Design and synthesis of novel combinations of polymers will expand the scope of new drug
delivery systems in the future.

40. CONCLUSION
Polymer‐based pharmaceuticals are starting to be seen as key elements to treat many lethal
diseases that affect A great number of individuals such as cancer or hepatitis.
NUMEROUS sysnthetic biodegradable polymer are available and still being developed for
sustained and targeted drug delivery application.
Biodegradable polymer have proven their potential for the development of new advanced and
efficient DDS and capable of delivering a wide range of bioactive matarials.
Nowadays ,biodegradable polymer are commonly found in many application from commodity
to hi-tech applications due to advancement in bio-technologies; however, despite these
advancement there are still some draw-backs which prevent the wider commercialization of
bio-based polymer in many application.
This is mainly due to performance and price when compared with their conventional
counterparts ,which remains a significant challenge for bio-based polymer.

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