Bioactive Polymers

INTRODUCTION

Bioactive polymer made of synthetic or artificial polymers

substituted with specific chemical functional groups carried by the

macromolecular chain are designed to develop specific interactions with living

systems.

When a polymeric material is exposed to a biological environment,

there is a natural tendency to induce different reactions such as blood coagulation,

complement activation and cell interactions.

Polymer scientists have synthesized a large number of polymers and

have evaluate their behavior when they are in contact with biomolecules, viruses,

bacteria, body fluids, cells and whole organisms.

Bioactive polymers are used to repair, restore or replace damaged or

diseased tissue or to interface with the physiological environment.

They are basically three main types of polymers used in a biological

environment.

Polymer used as bio materials, e.g. in organ replacement and bone surgery.

Polymers serve as matrices in devices that permit control release of an

active substance over along period of time.

Soluble polymers: synthetic polymers that themselves display biological

activities.

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Bioactive Polymers

Uses of bioactive polymers:

Bioactive polymers in medicines and surgery are currently widely

used and include intracorporeal, paracorporeal and extracorporeal (inside,

interfacing or outside the body, respectively) Applications are given below:

Intracorporeal Materials

Temporary devices:

Surgical dressings

Sutures

Adhesives

Polymeric intermedulary nails

Polymer - fiber composite bone plates

Simple semipermanent devices:

Tendons

Reinforcing meshes

Heart valves

Joint reconstruction & bone cement

Tubular devices

Soft-tissue replacement materials for cosmetic reconstruction

Drug delivery implants.

Complex devices simulating physiological processes:

Artificial kidney/Blood dialysis

Artificial lung/Blood oxygenator

Artificial pancreas/Insulin delivery system

Artificial heart

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Bioactive Polymers

According to a soon-to-be-released updated report from Business

Communications Company, Inc. the U.S. biocompatible materials market is

estimated at $8.2 billion in sales at the manufacturer's sales level in 2003.

Fueled by greater demand from the aging population and the relatively

short medical device product life cycles (as compared to other medical

products) this market is forecast to grow at a 7.7% AAGR (average annual

growth rate) through 2008 reaching nearly $1.9 billion.

The biocompatible materials market is a niche market comprised of

polymers, metals, advanced ceramics, natural materials, pyrolytic carbon,

composites and coatings. The industry requires superior grade materials in

relatively small volumes when compared to the volume of these materials

consumed in other industries.

PVC accounts for 80% of polymer consumption; other polymers commonly

consumed are silicone, polyurethane, polycarbonates, polyester and

polyethylene. Emerging polymer applications include biodegradable

polymers, bioactive polymers (polypeptides), hydrogels, molecular

imprinted polymers, conductive polymers and biopolymers. Many of these

are being applied to meshes, foams, sponges or hydrogels to stimulate

tissue growth.

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Bioactive Polymers

MARKET DATA

U.S. Market Size for Biocompatible Materials in Medical Devices,

through 2008 ($ Millions)

Materials 2003 2008AAGR %

2003-2008

Polymer 7,200 10,500 7.8

Metals 162.5 212.8 5.5

Other materials * 834.5 1,178.4 7.1

Total 8,197.0 11,891.2 7.7

Medical Device market using

biocompatible materials 38,000.0 57,380.0 8.6

* Includes advanced ceramics, natural materials, pyrolytic carbon, natural materials,

companies and coatings. Source: BCC, Inc.

U.S. Market Size for Biocompatible Materials in Medical Devices, through 2008

($ Millions)

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Bioactive Polymers

FEATURES OF BIOACTIVE POLYMERS Some of important properties should be required for bioactive polymers are as

follows.

Biocompatibility.

Mechanical, Physical and Chemical Properties.

Purity.

Fabrication.

Stability.

Tolerability.

Sterilizability.

Foreign body reaction.

Biocompatibility:

Acceptance of an artificial important by the surrounding tissue and by the

body as a whole.

Physical, Chemical & Mechanical Properties:

These must be capable with the proposed and for eg.. in the design of

heart , the flexing characteristics of the polymer have often been overlooked.

Polymer Purity :

Industrial reins are highly variable in nature from manufacture to

manufacturer. A variety of other materials incidental to the polymer process such

as residual initiators, initiator fragments, solvents, plasticizers, trapped free

radicals, inhibitors, lubricants, heat sand light stabilizers, fillers, parting agents,

anti oxidants, degradation products, curing agents, residual monomers and allow

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Bioactive Polymers

molecular weight oligomers may be present. There may be variations in the

molecular weight and in the mol. Wt. distribution, as well linkages and branching.

Ease of fabrication:

The desired device should be capable of fabrication without damages in

properties, surface characteristics, crystallinity, surface oxidation, or

contamination by processing aids such as oils, solvents or like that.

Stability:

Bioactive polymers should not be adversely affected by the normal

physiological environment. No biodegradation that could compromise function

over the short or long term should occur, and no process should release toxic to the

environment.

Tolerability:

Bioactive polymers should not exhibit toxic or irritant qualities, or elicit

adverse physiological responses locally or systemically. Toxicity can also be

affected by the rate of release of the substance and the biological processing and

removal of the substance.

Sterilizability:

The physical, chemical, mechanical and biochemical characteristics of the

device or material must not undergo any change during sterilization. This is often

not as easy as it may seem. Light, heat, radiation, or chemical treatment may be

used during this process.

Foreign body reaction:

The polymer should cause only minimal, if any, foreign body interaction,

inflammation, encapsulation or cell change response in the surrounding tissue. It

also should not cause tissue or other reaction rmote from the site of implantation

and should be free of response.

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Bioactive Polymers

Materials used as bioactive polymers

The following materials using as bioactive polymers.

PEUU’s [Poly(ether urhane urea )s]

Silicons

TFE polymers

PVC

Polyolefins

Polycarbonate

PMMA

Polyesters

Cellulose

Polyvinyl alcohol

Epoxy resins

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Bioactive Polymers

Comparison with Other Materials

PROPERTIES Glass Metal plastics

Flexibility Poor Poor Excellent

Clarity Excellent Poor Good

Design Versatility poor poor Excellent

Barrier Properties Excellent Excellent Good

Chemical ResistanceExcellent Poor Good

Saleability Poor Good Excellent

Performance weight/vol.

RatioPoor Poor Excellent

Cost/ Performance

Ratio Poor Poor Excellent

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Bioactive Polymers

Application of bioactive polymer

Application of bioactive polymers in artificial heart.

Numerous polymeric systems have been explored for use in cardiovascular

systems. For example the materials used in artificial heart studies include

Polyvinyl Chloride (PVC), silicone rubber (silatic), Polyurethane, Biomer and

polyolefin rubber. However among polyurethanes the most promising materials

appear to be some of the polyether urethane ureas.

Your heart is the engine inside your body that keeps everything running. Basically,

the heart is a muscular pump that maintains oxygen and blood circulation through

your lungs and body. In a day, your heart pumps about 2,000 gallons of blood.

Like any engine, if the heart is not well taken care of it can break down and pump

less efficiently, a condition called heart failure.

The AbioCor is the first artificial heart to be used in nearly two

decades.

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Bioactive Polymers

Until recently, the only option for many severe heart failure patients has been heart

transplants. However, there are only slightly more than 2,000 heart transplants

performed in the United States annually, meaning that tens of thousands of people

die waiting for a donor heart. On July 2, 2001, heart failure patients were given

new hope as surgeons at Jewish Hospital in Louisville, Kentucky, performed the

first artificial heart transplant in nearly two decades. The AbioCor Implantable

Replacement Heart is the first completely self-contained artificial heart and is

expected to at least double the life expectancy of heart patients.

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Bioactive Polymers

Application of bioactive polymers in artificial Lung

An artificial implantable lung that uses tiny hollow fibers and the heart’s

own pumping power to oxygenate blood is showing promise in pre-clinical

studies, and may reach clinical trials in about a year for lung failure patients

awaiting a lung transplant.

The materials used in artificial lung studies include Polyvinyl Chloride

(PVC), silicone rubber (silatic), Polyurethane, Biomer and polyolefin rubber.

However among polyurethanes the most promising materials appear to be some of

the polyether urethane ureas.

A heart-lung bypass machine can be used for major operations but it could

not be used to keep a patient alive who has a long-term lung problem or while

their lungs are recovering from some form of damage. Also, an artificial ventilator

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Bioactive Polymers

will not be of any use if the patient's lungs are unable to take in the oxygen

required.

To try and solve this problem, the University of Pittsburgh Medical Center,

in the United States, is developing an artificial lung that can sit inside a blood

vessel and oxygenate blood as it moves past a series of porous membrane tubes

attached to an external oxygen supply.

Called the Intravenous Membrane Oxygenator (IMO), it is intended to treat

patients with life-threatening lung problems. This could be due to some form of

trauma or it could be used with patients who have lung infections like pneumonia.

Their lungs cannot take in sufficient oxygen and the IMO is designed to add extra

oxygen to the blood before it gets to the patient's lungs. In this way the damaged

lungs are assisted until they are able to recover.

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Bioactive Polymers

Application of bioactive polymers in artificial kidney

Artificial kidney is another example of an interesting development in the

field of biomaterials. Artificial kidney is often referred to as haemodialysis unit

which removes waste products from the blood with polymeric semipermeable

membrane. Which purifies the blood against artificial liquids in a process known

as hemodialysis or peritoneal dialysis. In peritoneal dialysis, silicone elastomer or

polyurethane elastomer is generally used as caterers to access the peritoneal cavity

A polyester cuff surrounds the segment of each catheter. In haemodialysis, the

dialyser is normally made of several thousand hollow polymer fibers mounted in a

polyurethane potting . The dialysis tubing is generally made of PVC. The

membranes used are generally based on cellulose or cellulose derivatives.

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Bioactive Polymers

Advantages & Disadvantages

The major advantages and few disadvantages of bioactive polymers are as

follows.

Advantages

The bioactive polymers must be capable of good response from body

surrounding body tissue.

They will not cause of inflammation.

They will not produce infection.

They will not responsible for thrombogenesis.

No adverse immunological response or neoplasm induction or promotion.

The artificial heart and valve, kidney, lung saves the life of the patient by

improving the function of organ.

Disadvantages

Sometimes growth of bacteria takes place on the surface of implant.

Implant will be cause of cancer due to foreign body reaction.

Bioprosthetic valve fail due to calcification (Calcium from the blood

stream form deposits on the implant).

Bioprosthetic valves are also susceptible to mechanical fatigue.

Artificial heart, kidney, lung is more expensive and also involves great

risk of life.

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Bioactive Polymers

Scope

Recent advance in material science and surgery now make it possible to

rebuild many parts of the human body.

Some polymers have mechanical properties that resemble those of natural

tissues, making them suitable as bioactive polymers.

Polymer engineering coupled genetic engineering to produced material that

interact and control biological system.

The synthetic polymer industry has expanded and polymeric materials with

a vast spectrum of properties are available.

Conclusion

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Bioactive Polymers

Thus ,from the discussion we concluded that

Polymers are most important and largest family of materials being used in medical

technology such as used in conventional medical technology and ,surgery and drug

delivery.

Polymers have been used in the augmentation and repair of the human body

with much success.

Bioactive polymers must be capable of being used in or on human body

without eliciting rejection response from surrounding body tissues.

They must passed stringent tests to assured that they will not cause of

inflammation, infaction, thrombogenesis, adverse immunological response of

neoplasm induction or promotion.

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Bioactive Polymers

Bibliography

(1) Nass And Mark, “Encyclopedia of polymer Sci. & Engg.”

Vol 2, Second Edition, Pg-No. 243-280

(2) Nass And Mark, “Encyclopedia of polymer Sci. & Engg.”

Vol 9, Second Edition, Pg-No. 459-461,488-491

(3) J.A.Brydson “Plastics materials.” Sixth Edition,

Mar-Apr 1999, Pg-No. 345-370

Web Sites

http://www.expasy.ch/spdbv/mainpage.htm.

http://www.msi.com.

http://www.povray.org.

http://www.chemistry.mcmaster.ca/faculty/brook/bio.html

http://www.uroplasty.com/

http://www.biomedical.com/

CONTENTS

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Bioactive Polymers

Introduction

Market Data

Features of bioactive polymers

Bioactive polymers

Comparison with other material

Application of bioactive polymers

Advantage & Disadvantage

Scope

Conclusion

Bibliography

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