Download Polymer for Medical Applications

Polymer for Medical
Applications
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
α-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
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
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
Biodegradable Polymers as Drug
Carrier Systems
• Why nanoparticles are desired for drug
delivery system?
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
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)
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)
Schematic of different area of
chemistry
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
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
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Nonadhesion to dental structures
Low colour stability
Low molecular weight of monomer
High polymerization shrinkage
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
Commercial Suture materials
Braided Polyester
Multifilament nylon
Polythetrafluoroethylene
Textile based Biomaterials for
Surgical Application
• Wound closure biomaterials are divided
into;
– Suture materials
– Tissue adhesives
– staplers
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)
Table of Relative Tissue Reactivity
to Sutures
Textile based Biomaterials for
Surgical Application
• 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
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
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 elastomerfluoroelastomer, silicone elastomer, etc
– Thermoplastic elastomer
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.
Medical device
in human body