1. MASE 542/CHEM 442 BIOMATERIALS
Spring 2012
Assoc. Prof. H. Funda Yagci Acar
Koç University

2. Agenda Basic terminology/definition Types of materials
regulations/players
Types of materials
Metals/Ceramics/Polymers
Interaction of biomaterials with tissue
Body response
Testing
Examples
Student presentations

3. Examples Orthopedic Dental applications Ophtalmological applications
Adhesives, sealants
Sutures
Drug delivery
Diagnostics
Cardiovascular
Tissue engineering
Breast implants

4. Grading 25% Midterm (March 28) 25% Project (abstract due April 2)
50% Final

5. Biomaterial…What?
Medical devices include a broad range of products from simple tongue depressors to sophisticated programmable pacemakers with micro-chip technology. Medical devices include in vitro diagnostic products, such as general purpose lab equipment, reagents, and test kits, which may include monoclonal antibody technology. Certain electronic radiation emitting products with medical application and claims meet the definition of medical device. Examples include diagnostic ultrasound products, x-ray machines and medical lasers.
About 50,000 substitute heart valves are implanted annually in the United States, and this number is also growing. At present, the leading mechanical valve design has been implanted in more than one million patients worldwide. In total, the prosthetics industry exceeds $10B annually and is expected to grow rapidly in the next few decades; the orthopedics industry alone has been growing steadily at 10% annually.
Approximately 245,000 knee replacements are done annually in the United States, and this number is expected to grow rapidly as the population ages

6. Biomaterial…What?
Medical devices include a broad range of products from simple tongue depressors to sophisticated programmable pacemakers with micro-chip technology. Medical devices include in vitro diagnostic products, such as general purpose lab equipment, reagents, and test kits, which may include monoclonal antibody technology. Certain electronic radiation emitting products with medical application and claims meet the definition of medical device. Examples include diagnostic ultrasound products, x-ray machines and medical lasers.
About 50,000 substitute heart valves are implanted annually in the United States, and this number is also growing. At present, the leading mechanical valve design has been implanted in more than one million patients worldwide. In total, the prosthetics industry exceeds $10B annually and is expected to grow rapidly in the next few decades; the orthopedics industry alone has been growing steadily at 10% annually.
Approximately 245,000 knee replacements are done annually in the United States, and this number is expected to grow rapidly as the population ages

7. Perfect mechine… Self-regulating process
Feed back for internal balance
Maintain equilibrium
Continued disturbance – distructive response!

8. The Failing human machine
Spare parts
Bolts ……
Improve quality of life
Expand life-span

9. Biomaterial
A (nonviable) material used in a (medical) device, intended to interact with biological systems (Williams, 1987)
Any material of natural or of synthetic origin that comes in contact with tissue, blood or biological fluids, and intended for use in prosthetic, diagnostic, therapeutic or storage applications without adversely affecting the living organism and its components
Nonviable: not capable of living
If nonviable is removed we can also include many tissue engineering and artificial organs which use living cells
Id medical is out we can include abroader range, biochip

10. Biomaterials Missirlis:
A biomaterial is any material, single member of a generic class or a combination of two or more members out of the same or different classes, which can be used in a living body for a particular implant or group of implants, which does not incite negative response by the body, which is stable or exhibits only controlled and well-assessed breakdown.

11. Biocompatability
Biocompatability is the ability of a material to perform with an appropriate host response in a specific application (Williams, 1987)
When biomaterial in in contact with the living tissue it does not cause:
harmful tissue reactions (pain, swelling or necrosis)
causing a systemic toxic reaction
having tumorigenic potential

12. Biomaterial
Material
Performance
Bio-compatability

13. Yes Bio but also material…
understand the basic chemical and physical properties of materials
determine the need for the application
design your biomaterial
“Declare the past, diagnose the present, foretell the future; practise these acts. As to diseases, make a habit of two things: to help, or at least to do no harm. The art has four factors, the disease, the patient, the physician and the engineer.” From the “Epidemics of the Hippocratic Corpus [4, p.165]”
Need: mechanical strength, lifetime, degradation needed or not…size, shape…

14. Biomaterials Science Multidisciplinary: Multimaterial Need-driven
Scientist, manufacturer, patient, physician, attorney!
Multimaterial
Need-driven
Sustential market
Risk-benefit

15. Material-Performance
Metals
Ceramics
Polymers
Composites
Fibers, films, gels, foams, coatings, nanoparticles/nanotubes
From Ratner, pg 2

16. Magnitute of the Field
From Ratner, pg 3

17. Magnitute of the Field
From Ratner, pg 3

18. 75 million contact lense/ year worldwide 275 million hearth valves
500,000 total artificial hip and knee prostheses
Size of the market and economics
From Ratner, pg 3

19. Risk-benefit Cost/benefit, Cost/performance
Pateients with diseased aortic heart valves:
50% chance of dying within 3 yrs
Surgical replacement of the valve:
70% 10 years survival
If good quality of life 60% of these patients will suffer from valve problems in 10 years.
Cost of heart valve: $
Hospital bill: 60,000 $
About 10% requires replacement

20. Ethics

21. Regulations U.S. Food and Drug Administration (FDA)
International Standards Organization (ISO): worldwide

22. Requirements of Biomaterials
A biomaterial must be:
inert or specifically interactive
biocompatible
mechanically and chemically stable or
biodegradable
processable (for manufacturability)
nonthrombogenic (if blood-contacting)
sterilizable

23. Bio-inertness vs. Bioactivity
Bioactive materials have specific interactions with the surrounding tissue. Biocompatible material should affect the equilibrium of the body as little as possible
Do stg !
Don`t do anything!

24. Biocompatability testing
Determine potential toxicity resulting from contact of the biomaterial with the living tissue.
materials should not—either directly or through the release of their material constituents—produce adverse local or systemic effects
i.e. carcinogenic, adverse reproductive and developmental effects.
Need systematic testing to ensure that the benefits >> potential risks
Determine potential toxicity resulting from contact of the biomaterial with the living tissue.
The device materials should not—either directly or through the release of their material constituents—produce adverse local or systemic effects, be carcinogenic, or produce adverse reproductive and developmental effects.
Therefore, evaluation of any new device intended for human use requires data from systematic testing to ensure that the benefits provided by the final product will exceed any potential risks posed by device materials.

25. Classification of Medical Devices
Based on the duration of the device use, invasiveness and risk to the user.
Class I devices: minimal invasiveness, does not contact the user internally
crutches, bedpans, tongue depressors, adhesive bandages etc.
Class II devices: higher degree of invasiveness and risk, but relatively short duration.
hearing aids, blood pumps, catheters, contact lens, electrodes etc.
Class III devices: considerably more invasive and can pose immense risk to the user-implantables
cardiac pacemakers, intrauterine devices, intraocular lenses, heart valves, orthopedic implants, etc.

26. UHDPE...used for base bath
Polyester:fabric
Polyurethane...pants
MMA...bath tub

27. Commonly Used Biomaterials
Applications
Silicone rubber
Catheters, tubing
Dacron
Vascular grafts
Poly(methyl methacrylate)
Intraocular lenses, bone cement
Polyurethanes
Catheters, pacemaker leads
Stainless steel
Orthopedic devices, stents
Collagen (reprocessed)
Cosmetic surgery, wound dressings
DACROn: Du Pont PET
Usually, they were not originally engineered for biomaterials applications !!!

28. How to choose the material?
Application
Properties
Mechanical (ex., modulus)
Chemical (ex., degradation)
Optical (ex., whiteness, clarity)
Structure

29. What governs materials choice?
1. Bulk properties: matched to those of natural organs
2. Ability to Process
3. Federal Regulations: FDA
Rational design of biomaterials based on better understanding of natural materials and the material/biological organism interface

30. Example – Hip Implant
With age or certain illnesses joints deteriorate. Particularly those with large loads (such as hip).
Adapted from Materials Science and Engineering, Fig , Callister 7e.

31. Example – Hip Implant Requirements mechanical strength (many cycles)
good lubricity
biocompatibility
Adapted Materials Science and Engineering from Fig , Callister 7e.

32. Example – Hip Implant
Adapted from Fig , Callister 7e.

33. Hip Implant Key problems to overcome
fixation agent to hold acetabular cup
cup lubrication material
femoral stem – fixing agent (“glue”)
must avoid any debris in cup
Ball
Acetabular
Cup and Liner
Femoral
Stem
Adapted from chapter-opening photograph, Chapter 22, Callister 7e.