Characteristic of bioadhesive polymer

Bioadhesive polymers have their unique characteristic.

Following is the Characteristic of bioadhesive polymer

-bioadhesive polymer and degradation products should be non-toxic, non-irritant and free from leachable impurities.

- Bioadhesive polymer should have good spreadability, wetting, swelling and solubility, and biodegradability properties.

- Bioadhesive polymer shall adhere quickly to the mucosa and should process sufficient mechanical strength.

- Bioadhesive polymer possesses peel, tensile and shear strength at the bioadhesive range.

- Bioadhesive must be easily available and its cost should not be high.

- Bioadhesive polymer should show bioadhesive properties in both dry and liquid state.

- Bioadhesive polymer should have an acceptable shelf life.

- Bioadhesive should have optimum molecular weight.

- Bioadhesive polymer should have spatial confirmation.

- Bioadhesive should have sufficiently cross-linked but not to the degree of suppression of bond forming groups.

Properties of Polymer 
Application of Polymer

Method of studying Polymer Degradation
Polyethylene Glycol: Polymer 
chitosan Polymer Characteristic and Application  
Biodegradable Polymer
Biodegradation of Polymer

Poly ethylene glycol:Polymer

 Poly ethylene glycol (PEG) is hydrophilic non-ionic polyether that has  been shown to exhibit excellent biocompatibility .PEG is non toxic and has approved by the FDA  for internal consumption. Intravenously administered PEG is excreted by the kidney .In aqueous solution, PEG acts as a highly mobile molecule with a large exclusion volume.PEG is a neutral polymer with hydroxyl end groups that weak hydrogen bond acids and weakly basic ether linkage in the backbone.

One of the greatest interests in PEG for drug delivery system is its ability to extend residence time in the body. The mononuclear phagocytic system (MPS) (also known as the reticuloendothelial system)  is encompassed by a range of cells capable of phagocytizes. The primary function of the MPS is to remove the senescent cell from circulation and to provide phagocytic cell for both inflammatory and immune response.

Phagocytosis is a special form of endocytosis in which larger in which large particle are ingested by phagosomes. The immune system recognizes hydrophobic polymer particle ass foreign bodies and thus they are rapidly cleared required then the nanoparticle surface must be modified in order to prevent this rapid clearance. PEG-containing  PLGA nanoparticle has been shown to extend the half-life of  the protein bovine serum albumin on rats from minutes to hours .

Properties of Polymer 
Application of Polymer

Method of studying Polymer Degradation
Characteristic of bioadhesive Polymer 
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Biodegradable Polymer
Biodegradation of Polymer

Chitosan –Polymer Characteristic, Application

-Chitosan is natural polymer obtained by the hydrolysis of Chitin.

- Chitosan are biopolymers which most widely used in drug delivery system.

-Chitosan is linear polysaccharide composed of randomly distributed linked D-glucosamine (deacetylated unit ) and N-Acetyl-D-glucosamine (Acetylated Unit).

Characteristic of chitosan:

-Chitin is highly insoluble in common solvents and has close resemblance to cellulose by having similar solubility profile and low chemical reactivity.

-Chitosan is a principal derivative of chitin and chitosan are distinguished by their solubility profile in dilute aqueous acid solutions.

-The characteristics properties of chitosan that render them suitable for pharmaceutical and biomedical applications.

Application :

-The chitosan has received considerable attention as possible pharmaceutical excipient in both conventional and novel application such as diluents in tablets, disintegrating agent, wet granulation, film coating hydrogel, wetting agent, bioadhesive, sustain release of drugs, site specific drug delivery system, vaccine delivery etc.

-Pharmacological properties like antacid and antiulcer activity, hypocholesterolemic action and wound healing properties.

-Hemostatic and spermicidal properties owing to their ability to bind strongly to mammalian cells by virtue of their polycationic character.

-Presence of reactive functional group and cationic character opens up possibilities for their application in controlled drug delivery.

-Favorable biological properties like biodegradability, biocompatibility, and nontoxicity.

-The chitosan matrix formulation floats and gradually swells in acidic medium

-The chitosan polymer is used in different field like agriculture as a natural seed treatment, plant growth enhancer, and bio-pesticide. The chitosan polymer can be used as a hemostatic agent in bandages in health care. Chitosan in tablet form is used as fat attractors or as dietary fiber

-Chitosan polymer also used in colon-specific drug delivery system.

Properties of Polymer 
Application of Polymer
Method of studying Polymer Degradation
Characteristic of bioadhesive Polymer 
Polyethylene Glycol: Polymer 
Biodegradable Polymer
Biodegradation of Polymer

Methods of studying polymer degradation

There is a different method of study polymer degradation.

-Morphological changes(Swelling, deformation, bubbling, disappearance )

- Weight Loss

- Thermal Method

     Differential scanning calorimetry  

- Molecular weight Changes

      Dilute solution viscosity

      Size exclusion chromatography

      Gel permeation chromatography

      Mass spectroscopy

-Change in chemistry

    Infrared spectroscopy (IR)

    Nuclear magnetic resonance spectroscopy (NMR)

Properties of Polymer 
Application of Polymer
Characteristic of bioadhesive Polymer 
Polyethylene Glycol: Polymer 
chitosan Polymer Characteristic and Application  
Biodegradable Polymer
Biodegradation of Polymer

Properties of Polymers

Following are the properties of the polymer.

Physical property

-       Specific gravity

-       Mold shrinkage (in flow, cross-flow and thickness directions)

Mechanical Property

-       Strength

-       Elongation

-       Hardness

-       Impact of resistance

Environmental properties

-Chemical resistance

- UV resistance

- Flame resistance

-Water absorption

Thermal Properties:

-Heat defalcation Temperature

- Glass transition temperature

-Heat capacity

-Thermal conductivity

Electrical Properties:

-Surface and volume Resistively

-Dielectric constant

- Dielectric Strength

- Dissipation Factor

-Break down voltage  

Optical Properties:

-  Light transmission

-  Haze

-  Refractive Index

Morphology

- Crystallinity

- Orientation 

Application of Polymer

Method of studying Polymer Degradation

Characteristic of bioadhesive Polymer 

Polyethylene Glycol: Polymer 

chitosan Polymer Characteristic and Application  

Biodegradable Polymer

Biodegradation of Polymer

Tensile length

Definition:

The tensile strength of a material quantifies how much stress the material will endure before failing. This is very important in applications that rely upon polymer’s application physical strength or durability. In general  tensile strength increases with polymer length. 

Properties of Polymer 
Application of Polymer

Method of studying Polymer Degradation
Characteristic of bioadhesive Polymer 
Polyethylene Glycol: Polymer 
chitosan Polymer Characteristic and Application  
Biodegradable Polymer
Biodegradation of Polymer

Application of Polymer

Now a day’s Application of polymers in medical science is very common. Polymers are used for multiple medical applications. A wide range of different polymers is available which have different use as a medical device.

-Polymers used in implantation devices and therapeutic devices:

-Nowadays polymers used in Artificial joints, metallic femoral head. In stents and catheters tissue transplantation,  tissue replacement.

 -Bioabsorbable polymers for surgical applications as a suture. 

Bioabsorbable sutures are used in the fixation of bones fractures, closure of soft tissue and wound etc.

- Polymers for coating pharmaceutical dosage forms:

-In the pharmaceutical industry, drugs are coated to control the release of the drug

- Polymer for enteric coating example ethyl cellulose, cellulose are the example of the polymer which used  in enteric coated dosage forms.

- Polymer used as pharmaceutical excipient:

-Polymer are used as a binder, diluents, disintegrates .acacia gelatine, starch are the example of the binder. Gelatine is an example of the polymers which used in the manufacturing of the capsules.

- Polymer themselves as a drug:

Insulin heparin and protamine are the polymer which act as a drug and it has an active impact on the body.

-Polymers used in NDDS

-Bio adhesive polymers used in muco adhesive preparation, polymers also used in the preparation of transdermal patches, for the delivery of the genes in gene therapy.

-Polymer used in elastomers, plastic, films and fibres.

-Polymers are also used as emulsifier, suspending agent

-Polyaminoamide is employed for synthesis of dendrime and they can be exploited for transfection of cells. 

Properties of Polymer 

Method of studying Polymer Degradation
Characteristic of bioadhesive Polymer 
Polyethylene Glycol: Polymer 
chitosan Polymer Characteristic and Application  
Biodegradable Polymer
Biodegradation of Polymer

Introduction of polymer

-The polymer is a generic term used to describe very long molecules consisting of structural units and repeating units connected by covalent chemical bonds

Polymers consist of mainly of identical or similar unit joined together.

-The term polymer is derived from the Greek word: polys meaning many and meros meaning parts.

-The unit forming the repetitive pattern is called “mer” or monomer.

-According to the number of a reactive group present in the monomer, they are monofunctional (only one reacting group) e.g: acetic acid, alcohol

Bifunctional: Ethylene glycol, phthalic acid

Trifunctional: e.g glycerine

Tetra functional: divinylbenzene

History:

The term polymer was coined by Jons Jakob Berzelius . Around the same time, Henri Braconnot did pioneering work in derivative cellulose compounds. perhaps the earliest important work in polymer science.

Despite significant advances in the synthesis and characterization of polymers, a proper understanding of polymer molecular structure did not come until the 1920s.

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Biodegradable polymers

Definition of Biodegradable polymers:

Biodegradable polymers are defined as polymers comprised of monomers linked to one another through functional group and have unstable linkage in the backbone which degrades by the biological enzyme.

Advantages of biodegradable polymers:

-       It provides the drug at a constant controlled rate owes a prescribed period of time.

-       The polymers carrier would degrade into nontoxic, absorbable subunits which would be subsequently metabolized.

-       The system would be biocompatible would not exhibit dose dumping at any time and polymer would retain its characteristic until after depletion of the drug.

-       The degradable system eliminates the necessity for surgical removal of the implanted device following depletion of the drug.

Disadvantages of biodegradable polymers:

-       Sometimes the degradable polymers exhibit substantial dose dumping at some point following implantation.

-       A degradable system which is administered by injection of a particulate form is non-retrievable.

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Bio degradation of polymers

Definition of Biodegradation of polymers:

Biodegradation of polymer involves the successive chemical reaction such as hydrolysis oxidation /reduction with or without the aid of enzyme in living organism depending on the environmental condition.

Example:

Related to biodegradation are biological hydrolysis by hydrolase enzyme and oxidation by oxidoreductase enzyme. The reaction rate by the former route is generally faster than that by the latter route.

The hydrolase enzyme is responsible for the hydrolysis of the ester. Carbonate, amide and glycosidic linkage of the hydrolyzable polymer producing the corresponding low-molecular-weight oligomers. The oxidoreductase enzyme is responsible for the oxidation and reduction of ethylenic, carbonate amide, urethane, etc.

Hydrocarbon such as polyethylene, natural and polyisoprene rubbers lignin and coal are first subjected to biological oxidation by an oxidoreductase, such as hydroxylases, monooxygenases peroxidise and oxidases in the biodegradation process.

Introduction of Polymer
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Method of studying Polymer Degradation
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Polyethylene Glycol: Polymer 
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Method of studying Polymer degradation

FACTORS AFFECTING BIODEGRADATION OF THE POLYMERS

Following are the factor affecting the bio degradation of polymer 

 -Chemical structure

 -Chemical composition

 -Distribution of repeat units in multimers

 -Presence of ionic groups

 -Presence of chain defects or unexpected units

 -Configuration structure

 -Molecular weight

 -Molecular weight distribution

 -Morphology (amorphous/semi crystalline, microstructure, residual stresses)

-Presence of low molecular weight compound

-Processing condition

-Annealing

-Sterilization process

-Storage history

-Shape

-Implantation site

-Presence of absorbed or adsorbed compounds (water, lipid, ions, etc.)

-Physicochemical factors (pH, ion exchange, ionic strength)

-Physical factors (change in shape and size, variations of diffusion  coefficients, mechanical stresses, stress and solvent induced cracking)

-Hydrolytic mechanism

biodegradable polymer- Definition and advantages

Definition: - Polymer comprised of monomers linked to one another through functional group and have unstable linkage in the backbone. Biodegradable polymer degrading in biological fluid with release of dissolved or dispersed drug.

Disadvantage of non biodegradable polymer

 -Surgical removal of drug depleted polymer is difficult.

 -Toxic

- Not achieved constant rate of drug release.

Advantage of biodegradable polymers

 -Not require surgical removal of the drug.

 -Breakdown products are natural and biocompatible. So, there is no toxicity.

 -It give constant drug release.

 -Localized delivery of drug

 -Sustain delivery of drug

 -Stabilization of drug

 -Increase drug permeability