polymers for medical applications
TRANSCRIPT
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Polymer for Medical
Applications
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Biodegradable Polymers as Drug
Carrier Systems
Polyesters
Lactide/Glycolide Copolymers Have been used for the delivery of steriods,
anticancer agent, antibiotics, etc. PLLA is found as an excellent biomaterials and
safe for in vivo (Lactic acid contains an asymmetric-carbon atom with three different isomers as D-,L- and DL-lactic acid)
PLGA is most widely investigated biodegradablepolymers for drug delivery.
Lactide/glycolide copolymers have been subjectedto extensive animal and human trials without any
significant harmful side effects
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Poly(amides)
Natural Polymers
Remain attractive because they are natural
products of living organism, readily available,relatively inexpensive, etc.
Mostly focused on the use of proteins such as
gelatin, collagen, and albumin
Biodegradable Polymers as Drug
Carrier Systems
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Polymer Processing
Drug-incorporated matrices can be formulated
either compression or injection molding
Polymer & drug can be ground in a Micro Mill,
sieve into particle size of 90-120 m, then
press into circular disc
Alternatively drug can be mixed into moltenpolymer to form small chips, then it is fed into
injection molder to mold into desired shape
Biodegradable Polymers as Drug
Carrier Systems
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Why nanoparticles are desired for drug
delivery system?
Biodegradable Polymers as Drug
Carrier Systems
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Nanoparticles can be used to increase drug
solubility, have lower toxicity & target drug
delivery
In order to use nanoparticle as drug delivery,
they must satisfy number of criteria;
Biocompatible
Good drug payload
Manufacturing cost must be reasonable
Biodegradable Polymers as Drug
Carrier Systems
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Polymer for Dental Application
Four main groups of materials used in
dentistry;
Metal and alloys
Ceramics
Synthetic organic polymers & biopolymers
(derived from natural tissues)
Composites (an organic matrix polymers filledwith inorganic fine particles)
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In 19thcentury, gutth-percha was used forfilling
In 1909, PMMA was used as artificial teeth
filling In 1930s, polyamide, polyester,
polyethylene were prepared in different
forms (rigid, soft, fibers, adhesives, etc) forseveral applications (filling, implant,sutures, etc)
Polymer for Dental Application
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Schematic of different area of
chemistry
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Bases, liners and varnishes for cavities
There is a large diversity or organic and
inorganic materials for this purposes
Zinc polycarboxylate (or polyacrylate) cement
is prepared by mixing zinc oxide and the
polymer solution, and water solution ofpolyacrylic acid
Polymer for Dental Application
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Filling & Restorative Materials
Made up of organic matrix and inorganicparticulate or fibrous filling. Held together by
coupling agent PMMA resins have been used as filling
materials, but they have severaldisadvantages
Nonadhesion to dental structures Low colour stability
Low molecular weight of monomer
High polymerization shrinkage
Polymer for Dental Application
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2000 BC, natural fibers like linen, silk, horsehairwere used as suture materials
After world war II revolution of medical textile,
used of steel wire and synthetic fibers (PP,nylon, polyester)
In early 1970s, two synthetic absorbable woundclosure biomaterials, i.e. Dexon & Vicyrl were
introduced The four most widely used textile structure;
woven, knitted, nonwoven and braided
Textile based Biomaterials for
Surgical Application
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Commercial Suture materials
Braided PolyesterMultifilament nylon
Polythetrafluoroethylene
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Wound closure biomaterials are divided
into;
Suture materials
Tissue adhesives
staplers
Textile based Biomaterials for
Surgical Application
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Suture- is a strand of textile materials (natural orsynthetic), used to ligate blood vessel and drawtissue together
Ideal suture should Physical and mechanical properties (adequate tensile
strength, etc)
Handling properties (easy to handle)
Biological properties (unfavourable for bacterialgrowth)
Biodegradation properties (absorbable; its tensilestrength loss must match the healing rate of the tissueto be closed)
Textile based Biomaterials for
Surgical Application
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Table of Relative Tissue Reactivity
to Sutures
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Suture materials can be classified into 2
broad categories;
Absorbable;loss their entire tensile strength
within two to three months
Nonabsorbable; retain their strength longer
than two to three months
Textile based Biomaterials for
Surgical Application
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Biocompatibility of Elastomer
Elastomer-definition
Flexible- i.e.have low rigidity
Highly deformable, i.e. able to withstand
strong deforming forces without rupturing and
have elongation at rupture over 200%
Elastic or resilient, i.e. able to return to their
original shape and size after deforming forcesis removed
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Various famililes of Elastomers
General-use elastomer- natural rubber (NR),styrene butadiene rubber (SBR), etc
Special elastomer- ethylene propylene anddiene copolymer (EPM, EPDM), nitrilebutadiene copolymer (NBR)
Very special elastomers- high thermal and/or
chemical resistance elastomer-fluoroelastomer, silicone elastomer, etc
Thermoplastic elastomer
Biocompatibility of Elastomer
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Silicone elastomer
Widely used because it is strong, very mobile
bone of their Si-O-Si (siloxane) caternary
backbone; which provide chemical inertnessand flexibility, stable over time at a body
temp., show little tissue reactivity, and highly
resistant to chemical attack and heat.
Biocompatibility of Elastomer
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Medical device
in human body