Polymer for Medical Applications

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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 a-carbon atom with three different
  isomers as D-, L- and DL-lactic acid)
• PLGA is most widely investigated biodegradable
  polymers for drug delivery.
• Lactide/glycolide copolymers have been subjected
  to extensive animal and human trials without any
  significant harmful side effects

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Biodegradable Polymers as Drug Carrier Systems

• 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

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Biodegradable Polymers as Drug Carrier Systems

• 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 µm, then press
  into circular disc
• Alternatively drug can be mixed into molten
  polymer to form small chips, then it is fed into
  injection molder to mold into desired shape

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Biodegradable Polymers as Drug Carrier Systems

• Why nanoparticles are desired for drug delivery
  system?

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Biodegradable Polymers as Drug Carrier Systems

• 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

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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 filled
  with inorganic fine particles)

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Polymer for Dental Application

• In 19th century, gutth-percha was used for
  filling
• In 1909, PMMA was used as artificial teeth
  filling
• In 1930s, polyamide, polyester, polyethylene were
  prepared in different forms (rigid, soft, fibers,
  adhesives, etc) for several applications
  (filling, implant, sutures, etc)

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Schematic of different area of chemistry
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Polymer for Dental Application

• 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 of polyacrylic acid

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Polymer for Dental Application

• Filling Restorative Materials
• Made up of organic matrix and inorganic
  particulate or fibrous filling. Held together by
  coupling agent
• PMMA resins have been used as filling materials,
  but they have several disadvantages
• Nonadhesion to dental structures
• Low colour stability
• Low molecular weight of monomer
• High polymerization shrinkage

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Textile based Biomaterials for Surgical
Application

• 2000 BC, natural fibers like linen, silk,
  horsehair were 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 wound
  closure biomaterials, i.e. Dexon Vicyrl were
  introduced
• The four most widely used textile structure
  woven, knitted, nonwoven and braided

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Commercial Suture materials
Multifilament nylon
Braided Polyester
Polythetrafluoroethylene
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Textile based Biomaterials for Surgical
Application

• Wound closure biomaterials are divided into
• Suture materials
• Tissue adhesives
• staplers

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Textile based Biomaterials for Surgical
Application

• Suture- is a strand of textile materials (natural
  or synthetic), used to ligate blood vessel and
  draw tissue together
• Ideal suture should
• Physical and mechanical properties (adequate
  tensile strength, etc)
• Handling properties (easy to handle)
• Biological properties (unfavourable for bacterial
  growth)
• Biodegradation properties (absorbable its
  tensile strength loss must match the healing rate
  of the tissue to be closed)

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Table of Relative Tissue Reactivity to Sutures
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Textile based Biomaterials for Surgical
Application

• Suture materials can be classified into 2 broad
  categories
• Absorbableloss their entire tensile strength
  within two to three months
• Nonabsorbable retain their strength longer than
  two to three months

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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
  forces is removed

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Biocompatibility of Elastomer

• Various famililes of Elastomers
• General-use elastomer- natural rubber (NR),
  styrene butadiene rubber (SBR), etc
• Special elastomer- ethylene propylene and diene
  copolymer (EPM, EPDM), nitrile butadiene
  copolymer (NBR)
• Very special elastomers- high thermal and/or
  chemical resistance elastomer- fluoroelastomer,
  silicone elastomer, etc
• Thermoplastic elastomer

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Biocompatibility of Elastomer

• Silicone elastomer
• Widely used because it is strong, very mobile
  bone of their Si-O-Si (siloxane) caternary
  backbone which provide chemical inertness and
  flexibility, stable over time at a body temp.,
  show little tissue reactivity, and highly
  resistant to chemical attack and heat.

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Medical device in human body