2. Where can you find uses for polymers?
• Everywhere!
– There seems to be endless
uses for polymers
• Why?
– Easier to produce
– Biocompatibility
– Often cheaper
– Designed to mimic
– Replacement to old practices
– Designed to prevent additional
surgery/trauma to patient
3.
4.
5. 1. Medical Packaging &
Pharmaceutical
• The requirements for medical products packaging are
medium and high barrier protection
• The demand for sterilizable packaging for hospital and
industry is being met by special paper, plastic films,
and other nonwoven materials.
• Examples of medical packaging:
chlorinated tetrafluoroethylene (CTFE) is used in an
antibiotic test kit where even trace amounts of
moisture would violate the accurace of the test,
poly(ethylene terephthalate) (PET) is used as medical
containers, the advantages over glass include no
breakage of filling lines and higher output.
6. The principal advantages of PVC are the low cost and the ease of thermoforming.
The main disadvantages are the poor barrier against moisture ingress and oxygen
ingress; moreover PVC has a negative environmental connotation due to its
chlorine content. In the case of blister packaging the PVC sheet does not contain
any plasticizer and is sometimes referred to as Rigid PVC or RPVC. In the absence
of plasticizers, PVC blisters offer structural rigidity and physical protection for the
pharmaceutical dosage form. On the other hand, the blister cavity must remain
accessible by the push-through effect and the formed web may not be too hard to
collapse when pressed upon; for this reason the PVC sheet thickness is typically
chosen between 200µ to 300µ depending on the cavity size and shape. Most PVC
sheets for pharmaceutical blisters are 250µ or 0.250 mm in thickness.
Blister pack for
pharmaceutical
tablets / pills –
usually made of
PVC
7. RESIN PRIMARY FEATURES TYPICAL APPLICATIONS
Polyethylene Processing ease, chemical
resistance
Caps, needle hubs, medical
packaging, waste bags
Polypropylene Autoclavibility, contact
clarity
Syringes, specimen
collection cups
Gen-purpose polystyrene Transparency Petri dishes, labware, test
tubes
High-impact polystyrene Toughness, opacity Home test kits, diagnostic
equipment, housing
Styrene-acrylonitrile Chemical resistance,
transparency, toughness
Diagnostic components,
fluid handling devices, flat
plate dialyzers
Acrylic High light-transmission
rates, chemical resistance
I.V components, specimen-
collection containers
Acrylonitrile-butadiene-
styrene
Toughness, low and high
gloss, good processability
Home test kits, housing,
surgical staplers,
I.V.connectors
8. Polycarbonate Chemical and heat
rasistance, toughness,
transparency
Blood centrifuge bowls,
cardiotomy reservoirs,
profusion devices,
hemodialyzers
Polyester Chemical resistance I.V.components, catheters,
surgical instrument,
housings
Poly(vinyl chloride) Transparency, good scuff
resistannce
Blood bags, catheters,
cannulae, corrugated
tubing, renal care product,
transfusion supplies, face
masks
Polyurethane Good chemical resistance,
toughness, good
processability
Catheters, tubing,
I.V.connectors, drug
delivery systems
Polyetherimide Autoclavibility, chemical
resistance
Sterilization trays
Polysulfone High heat resistance Medical trays
9. Drug delivery refers to approaches, formulations,
technologies, and systems for transporting a
pharmaceutical compound in the body as needed to
safely achieve its desired therapeutic effect.
2. Polymers in Drug Delivery
Ideal requirements of implantable drug delivery systems:
- Environmentally stable.
- Biocompatible.
- Sterile.
- Biostable.
- Improve patient compliance by reducing the frequency of
drug administration over the entire period of treatment.
- Release the drug in a rate-controlled manner that leads to
enhanced effectiveness and reduction in side effects.
- Readily retrievable by medical personnel to terminate
medication.
- Easy to manufacture and relatively inexpensive.
11. Carriers which are able
to biodegrade include:
Liposomes;
Microspheres made of the
biodegradable polymer
poly(lactic-co-glycolic) acid
albumin microspheres;
synthetic
polymers (soluble);
nanofibers
Protein-DNA complexes;
protein conjugates;
erythrocytes
virosomes
Dendrimers - is hot in
biomedical research field.
12.
13. Why Would a Medical Practitioner Like a Material
to Degrade in the Body?
BONE+PLATE
BONE PLATE
Time
Mechanical
Strength
Degradable Polymer
Plate
Do not require a
second surgery for
removal
Avoid stress shielding
Offer tremendous
potential as the basis
for controlled drug
delivery
17. The two main types of capsules are:
1. Hard-shelled capsules, which are typically made using gelatin and contain dry,
powdered ingredients or miniature pellets made by, e.g. processes
of extrusion or spheronisation.
2. Soft-shelled capsules, primarily used for oils and for active ingredients that are
dissolved or suspended in oil.
Both of these classes of capsules are made from aqueous solutions of gelling
agents like:
Animal protein mainly gelatin;
Plant polysaccharides or their derivatives like carrageenans and modified
forms of starch and cellulose.
Other ingredients can be added to the gelling agent solution like plasticizers such
as glycerin and/or sorbitol to decrease the capsule's hardness, coloring
agents, preservatives, disintegrants, lubricants and surface treatment.
DISSOLVING CAPSULES
18. Liposomes are a form of vesicles that consist either of many, few or just one
phospholipid bilayers. The polar character of the liposomal core enables polar drug
molecules to be encapsulated. Amphiphilic and lipophilic molecules are solubilized
within the phospholipid bilayer according to their affinity towards the phospholipids.
Channel proteins can be incorporated without loss of their activity within the
hydrophobic domain of vesicle membranes, acting as a size-selective filter, only
allowing passive diffusion of small solutes such as ions, nutrients and antibiotics. Thus,
drugs that are encapsulated in a nano-cage-functionalized with channel proteins are
effectively protected from premature degradation by proteolytic enzymes. The drug
molecule, however, is able to diffuse through the channel, driven by the concentration
difference between the interior and the exterior of the nano-cage.
Degradable delivery vesicle
Example: Liposomes
drugs
19. Biodegradable Polymers as Drug
Carrier Systems
• Polyesters
– Lactide/Glycolide Copolymers
• Have been used for the delivery of steriods,
anticancer agent, antibiotics, etc.
• Poly-L-lactide (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)
• Poly(lactic-co-glycolic 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
20. 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
21. Biodegradable Polymers as Drug
Carrier Systems
2. 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
22. Biodegradable Polymers as Drug
Carrier Systems
• Why nanoparticles are desired for drug
delivery system ?
• 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
23. A multifunctional theranostic platform based on
photosensitizer-loaded plasmonic vesicular
assemblies of gold nanoparticles (GNPs) is
developed for effective cancer imaging and
treatment.
25. BIOMATERIAL FOR IMPLANTABLE MEDICAL COMPONENTS
What are Biomaterials?
Materials that are used and adapted for a medical application, so they are
intended to interact with a biological systems.
A medical device manufactured to replace a missing biological structure,
support a damaged biological structure, or enhance an existing biological
structure.
What is an Implant?
Requirements?
First and foremost, a biomaterial must be biocompatible, which means it should
not elicit an adverse response from the body, and vice versa. The biomaterial
should possess adequate physical and mechanical properties, biostability to
serve as augmentation or replacement of body tissues. For practical use, a
biomaterial should be readily available with a relatively low cost, be easily
processable and amenable to being formed or shaped.6
28. Polymeric materials have a wide variety of applications
for implantation, as they can be easily fabricated into
many forms: fibers, textiles, films, foams, solid, rods,
powders, liquids etc.
When given a choice of biostable elastomers for long-
term implants, two classes of polymers dominate. These
are crosslinked silicones elastomer and thermoplastic
polyurethanes (TPUs). Silicones and thermoplastic
polyurethanes have been widely used in implantable
devices for over 30 years.
29. The use of silicone materials in medical implantable
devices can be seen for example in facial, breast,
pacemaker and cochlear implants.6 However, the
applications of silicone elastomer are often limited due to
the inherently poor mechanical properties of these
materials, particularly in relation to tensile and tear
strength, abrasion, and flex-fatigue life.
30. Another disadvantage of conventional silicone elastomers in device
manufacturing is the need for crosslinking to develop useful
properties. This crosslinking process is needed to form chemical
bonds among adjacent polymer chains in order to gain rubber
elasticity and the physical-mechanical properties required. However,
once crosslinked, the resulting thermoset silicone cannot be
redissolved or remelted. This reduces the number of post-fabrication
operations that can be used in device manufacturing with these
silicones, relative to those possible with thermoplastic biomaterials
such as thermal forming, tipping, and tapering, radio-frequency
welding, heat sealing and solvent bonding.
31. Thermoplastic Polyurethane (TPU)
Thermoplastic Polyurethanes (TPUs) generally have mechanical
properties superior to silicone elastomers, are biocompatible and are
now being commonly used as biomaterials.
TPUs are very attractive candidates as biomaterials especially for
the mimicking of soft tissue, due to their great flexibility in properties
and ease of processing. Generally, TPUs have excellent physical
properties, combining high elongation and high tensile strength to
form tough, albeit fairly high-modulus elastomers.
This polymer shows good blood compatibility. It is also
noncytotoxic and does not give rise to adverse tissue reactions.
32. Example 1: COCHLEAR IMPLANT
Biomedical device that restores hearing
Electrode array:
- The part of the implant that delivers
sound to the patient’s hearing nerve
- Currently employing soft silicone
materials as insulation and protection
1. External sound processor
2. Sound processor
3. Electrode array
4. Auditory nerve
http://www.cochlear.com/au/hearing-loss-teatments/cochlear-implants-adults
Figure 1: Cochlear implant
Figure 2: Electrode arrays, which are
attached to the cochlear implant
33. Example 2: Dental implant
The problem: Oral Deficiencies
• Oral bone deficiencies are a major Issue!
– High prevalence of periodontitis
– Injury/trauma to jaw bone or teeth
– Other deficiencies from birth defects (i.e. cleft
palate/lip)
http://www.rad.washington.edu/staticpix/mskbook/MandibleFx.gif
http://www.ohiohealth.com/mayo/images/image_popup/fl7_cleft_palate.jpg
34. The Solution:
Bone Augmentation
• Performed to increase the amount of bone
to allow for secure implant placement
• Common procedures:
1) Alveolar process augmentation of mandible and/or
maxilla
2) Maxillary sinus augmentation
http://davidhan.info/yahoo_site_admin/assets/images/bf-Picture4.242141428_std.jpg
http://www.dr.agravat.com/images/bone_grafting02.jpg
http://www.drleonedds.com/images/photos/bonegraft1.jpg
36. If you don't like the idea of having bone removed from your body to be placed in your jaw,
other excellent options are available. Your dentist can use materials made from the bone of
human cadavers or cows. Synthetic materials also can be used for bone grafting. Newer
products, such as bone morphogenetic protein-2 (BMP-2), also are available. BMP-2
stimulates certain body cells to turn into bone, without grafting. This protein occurs naturally
in the body. The dental material is produced using DNA technology.
An excellent choice for a bone graft is your own bone. This most likely will come from your
chin or ramus (the back part of your lower jaw). If your dentist cannot get enough bone from
these areas, he or she may need to get bone from your hip or shin bone (tibia) instead.
Bone augmentation is a term that describes a
variety of procedures used to "build" bone so that
dental implants can be placed. These procedures
typically involve grafting (adding) bone or bonelike
materials to the jaw. The graft can be your own
bone or be processed bone (off the shelf) obtained
from a cadaver. After grafting, you have to wait
several months for the grafted material to fuse with
the existing bone. "Off–the-shelf" grafted materials
either cause surrounding bone to grow into the
graft or cause cells around the graft to change into
bone. A graft from your own bone transplants bone
cells or a block of bone that fuses to the jaw.
37. Problem with bone graft augmentation
Donor site morbidity
http://scottfross.com/wp-content/uploads/2009/12/bone-graft1.jpg
38. HYDROGELS
Hydrogel is a network of polymer chains
that are hydrophilic, sometimes found as
a colloidal gel in which water is the
dispersion medium. Hydrogels are
highly absorbent (they can contain over
90% water) natural or synthetic polymeric
networks.
39. Hydrogels for biomedical
applications
Benefits
- Closest analogue to living tissue
- Capable of binding large amounts of fluids and drugs, incl. proteins
- Swelling ratio controllable by variation in structure (mostly by the
hydrophobic/hydrophilic ratio)
- Small changes in temperature, pH, electric/magnetic field can trigger
large volume change/release of drug
- In many cases well defined release patterns - ~ t1/2
Drawbacks
- More difficult to characterize/predict behavior
- Not as well defined as stoichiometric compounds
40. HYDROGELS
Hydrogels find their name from their affinity for water and
incorporation of water into their structure.
The concentration of water in the hydrogel can affect the
interfacial free energy of the hydrogel,as well as the
biocompatibility.
Hydrogels have inherently weak mechanical properties.
41. Common uses for hydrogels include:
Currently used as scaffolds in tissue engineering. When used as scaffolds,
hydrogels may contain human cells to repair tissue. *hydrogel-coated wells
have been used for cell culture[10]
Environmentally sensitive hydrogels which are also known as 'Smart Gels'
or 'Intelligent Gels'. These hydrogels have the ability to sense changes of
pH, temperature, or the concentration of metabolite and release their load
as result of such a change.
As sustained-release drug delivery systems.
Provide absorption, desloughing and debriding of necrotic and fibrotic
tissue.
hydrogels that are responsive to specific molecules, such as glucose or
antigens, can be used as biosensors, as well as in DDS[clarification needed].
used in disposable diapers where they absorb urine, or in sanitary napkins
contact lenses (silicone hydrogels, polyacrylamides, polymacon)
EEG and ECG medical electrodes using hydrogels composed of cross-
linked polymers (polyethylene oxide, polyAMPS and polyvinylpyrrolidone)
water gel explosives
42. HYDROGELS
The interest in hydrogels as biomaterials stems from a
number of advantages such as
(1)The soft, rubbery nature of hydrogels minimize
mechanical and frictional irritation to the surrounding
tissues.
(2)These polymers may have low or zero interfacial
tension with surrounding biological fluids and tissues,
thereby, minimizing the driving force for protein
adsorption and cell adhesion
(3) Hydrogels allow the permeating and diffusion of low
molecular weight metabolities,waste products and salts
as do living tissues.
43. HYDROGELS
Poly (hydroxyethyl methacrylate) (PHEMA) is a rigid
acrylic polymer when dry, but it absorbs water when
placed in aqueous solution and changes into and elastic
gel.
Depending on the fabrication techniques,3 to 90% of its
weight can be made up of water.
Usually PHEMA Hydrogel takes up approximately 40%
water, and it is transparent when wet.
Since it can be easily machined while dry, yet is very
pliable when wet, it makes a useful contact lens
material.
44. Polymer Specific Properties Biomedical uses
Polyethylene Low cost, easy Possibility excellent
electrical insulation properties,
excellent chemical resistance,
toughness and flexibility even at low
temperatures
Tubes for various
catheters, hip
joint, knee joint
prostheses
Polypropylene Excellent chemical resistance, weak
permeability to water vapors good
transparency and surface reflection.
Yarn for surgery,
sutures
Tetrafluoroethylene Chemical inertness, exceptional
weathering and heat resistance,
nonadhesive, very low coefficient of
friction
Vascular and
auditory
prostheses,
catheters tubes
SEVERAL EXAMPLES OF BIOMEDICAL POLYMERS / POLYMERIC
BIOMATERIALS
45. Polymer Specific Properties Biomedical uses
Polyvinylchloride Excellent resistance to abrasion, good
dimensional stability, high
chemical resistance to acids,
alkalis, oils, fats, alcohols, and
aliphatic hydrocarbons
Flexible or semi-
flexible medical
tubes, catheter, inner
tubes components of
dialysis installation
and temporary blood
storage devices
Polyacetals Stiffness, fatigue endurance,
resistance to creep, excellent
resistance to action of humidity
gas and solvents
Hard tissue replacement
Polymethyl
methacrylate
Optical properties, exceptional
transparency, and thermo
formation and welding
Bone cement,
intraocular lenses,
contact lenses,
46. Polymer Specific Properties Biomedical uses
Polycarbonate Rigidity and toughness upto
1400C transparency, good
Electricalinsulator,
physiological inertness
Syringes, arterial tubules,
hard tissue replacement
Polyethylene
terephythalate
Transparency, good resistance to
traction and tearing, resistance
to oils, fats, organic solvents
Vascular, laryngeal,
esophageal prostheses,
surgical sututes, knitted
vascular prostheses.
Polyamide Very good mechanical properties,
resistance to absrasion and
breaking, stability to shock and
fatigue, low friction
coefficient, good thermal
properties,
PA 6 tunes for intracardiac
catheters, urethral
sound; surgical suture,
films for packages,
dialysis devices
components,
47. Polymer Specific Properties Biomedical uses
Polyurethane Exceptional resistance to
abrasion, high resistance
to breaking, very high
elasticity modulus at
compression, traction
and sheering remarkable
elongation to breaking.
Adhesives, dental materials,
blood pumps, artificial hear
and skin
Silicone
rubber
Good thermal stability,
resistance to
atmospheric and
oxidative agents,
physiological inertness
Encapsulant for pacemakers,
burn treatments, shunt,
Mammary prostheses, foam
dressing, valve, catheter,
contact lenses, membrances,
maxillofacial implants.
48. POLYAMIDES
Polyamides are obtained through condensation of
diamine and diacid derivative.
These polymers are known as nylons and are
designated by the number of carbon atoms in the parent
monomers.
These polymers have excellent fiber forming properties
due to inter-chain hydrogen bonding and high degree of
crystallinity, which increases the strength in the fiber
direction.
49. POLYAMIDES
Since the hydrogen bonds play a major role in
determining properties, the number and distribution of
amide bonds are important factors.
Nylon tubes find applications in catheters.
The coated nylon sutures find wide biomedical
applications.
Nylon is also utilized fabrication of hypodermic syringes
50. References
• Borrell, Luisa N., and Natalie D. Crawford. "Social Disparities in Periodontitis Among
United States Adults 1999-2004." Community Dent Oral Epidemiol 36 (2008): 383-91.
• Chapple, Iain L.C., Mike R. Milward, and Thomas Dietrich. "The Prevalence of
Inflammatory Periodontitis Is Negatively Associated with Serum Antioxidant
Concentrations." Journal of Nutrition 137 (2007): 657-64.
• Karadag, Erdener, and Dursun Saraydm. "Swelling Studies of Super Water Retainer
Acrylamide/crotonic Acid Hydrogels Crosslinked by Trimethylolpropane Triacrylate and
1,4-butanediol Dimethacrylate." Polymer Bulletin 48 (2002): 299-307.
• Tonetti, Maurizio S., and Andrea Mombelli. "Early-Onset Periodontitis." Ann Periodontol
4.1 (1999): 39-52.
• Williams, D. Chester, Progress in Biomedical Engineering, Elsevier, Amsterdam: 1987.
• Black, J., Biological performance of materials: fundamentals of biocompatibility. CRC
Press: 2006.
