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					          P8 037:
Introduction to Biomaterials
       生醫材料導論
     (Taught in English)
                 葉明龍
             Phone: 63429
     Email: mlyeh@mail.ncku.edu.tw


                                     1
      Alternative:
        P8 017
Chemistry of Biomaterials
    生物材料化學
         張憲彰
        Wed. 5-7


                            2
 Time: Mon. 6-8 (2:10-5:00 PM)
 Office hours: Wednesday, Thursday
  10AM -12PM (Biomedical Engineering
  5751A)
 Grade:
     Homework: 30%
     Tests: 50%
     Final paper and Presentation: 20%

                                          3/68
                   Textbooks:
Intend for Non-Materials background
 Fundamentals of Materials Science and
  Engineering (Chap 2-9)
    By: William D. Callister Jr.
   Biomaterials Science: An Introduction
    to Materials in Medicine (Chap 1, 2)
    By: Ruddy D. Ratner; Allan Hoffman; Frederick
    Schoen and Jack Lemons
                                                    4/68
   Introductory book:
    生物醫學材料 王盈錦
   References:
    1. Biomaterials
        by Sujata Bhat
    2. Biomaterials: An Introduction
        by Joon Bu Park


                                       5/68
      Students Self Introduction
1.   Fill your name, email, phone, Institute,
     Grade (Year) and Advisor
2.   Name, Institute, Grade (Year)
3.   Advisor
4.   Main focus of your lab
5.   Possible research direction


                                                6/68
                     Curriculum:
Week Content
1. Opening statement: Introduction (Biomaterials Page 1-9)
2. I. Materials Science and Engineering
        Chap 2 Atomic Structure and Interatomic Bonding
        Chap 3. Structures of Metals and Ceramics
3. Chap 4. Polymer Structure
        Chap 5 Imperfections in Solids
4. Chap 6. Diffusion
        Chap 7. Mechanical Properties
5. Chap 8. Deformation and Strengthening Mechanisms
        Chap 9. Failure
6. Test I
                                                             7/68
                      Curriculum:
7. II. Biomaterials
           1.4 Surface properties and surface characterization
           1.5 Role of water in biomaterials
8. 2.2 Polymers
9. 2.3 Silicone Biomaterials
          2.4 Medical fibers and biotextiles
10. 2.5 Hydorgels
          2.6 Smart Polymers
11. 2.7 Bioresorbable and Bioerodible Materials
           2.8 Natural Materials
12. 2.9 Metals
                                                                 8/68
                  Curriculum:
13.    2.10 Ceramics, Glasses, and Glass-Ceramics
14 .   2.11 Pyrolytic Carbon
              2.12 Composite
15 .   2.13 Nonfouling surfaces
              2.14 Physicochemical Surface modification
16 .   2.15 Textured and Porous Materials
              2.16 Surface-Immobilized Biomolecules
17.    Final presentation
18 .   Test II

                                                          9/68
       Biomaterials: Definition
   (1987, Williams) A biomaterial is a nonviable
    material used in a medical device, intended to
    interact with biological system.

   (Bhat) Nondrug material that can be used to
    treat, enhance or replace any tissue, organ, or
    function in a organism.
   (Bhat) Biological derived material that is used
    for its structural rather than its biological
    properties.

                                                 10/68
                Definition:
   (Merriam-Webster) Materials used for or
    suitable for used in prostheses that
    comes in direct contact with living
    tissues.

   Biocompatibility: ability of a material to
    perform with an appropriate host
    response in a specific application
                                                 11/68
                        Introduction
   Biomaterials used in these devices:
      ophthalmology,
      cardiology,
      neuromuscular surgery,
      orthopedics and
      dentistry.
   All biomaterials in common;
       they must have intimate contact with patient’s tissue or body
        fluid,
       providing a real physical interface.


   The search for new, more reliable devices require a
    disciplined scientific approach to the subject.                     12/68
     Introduction: Biocompatibility
   Good biocompatibility is achieved when the
    material exists within a living body without
    adversely or significantly affecting it or being
    affected by it.
   The material should have adequate mechanical
    strength, chemical and physical properties.
   Thus biomaterials must be compatible with body
    tissues mechanically, chemically as well as
    pharmacologically.

                                                  13/68
               Introduction
    To research these materials the
     investigator need to have arrange of
     techniques for
1.   materials production,
2.   measurement of strength and surface
     properties and
3.   in vitro and in vivo techniques for
     biocompatibility evaluation.
                                            14/68
                      Introduction
   The functions of implants fall into one the
    following categories:
       Load bearing or transmission artificial joint, fracture
        fixation
       The control of fluid flow in order to stimulate normal
        physiological function or situation vascular graft,
        stent
       Passive space filling either for cosmetic reasons or
        functional reasons bone filling, skin
       Generation of electric stimuli and transmission of light
        and sound. electrode
                                                              15/68
    Biomaterials: General perspective

       Biomaterials was also used to
      grow cells in culture,
     in apparatus for handling protein in
       laboratory,
     devices to regulate fertility in cattle,
     in aquaculture of oyster, cell-silicon
       “biochip”.
    Biomaterials are rarely used as simple
     materials, integrated into devices (final
     fabricated, sterilized form)
                                                 16/68
             Biomaterials science
   The physical and biological study of materials and their
    interaction with the biological environment.
   Traditionally investigation:
       biomaterials synthesis, optimization, characterization,
        testing
       the biology of host-material interactions.
       Most biomaterials introduce a non-specific, stereotyped
        biological reaction.

   Current effort:
       toward the development of engineered surfaces that could
        elicit rapid and highly precise reactions with cells and
        proteins,
       tailored to a specific application.
                                                                  17/68
            Biocompatibility
 Indeed, a complementary definition
  essential for understanding the goal (i.e.,
  specific end applications ) of biomaterials
  science is that of “biocompatibility”.
 "Biocompatibility” is the ability of a material
  to perform with an appropriate host
  response in a specific application
  (Williams, 1987).

                                               18/68
              Biocompatibility
   Examples of "appropriate host responses"
    include
     the resistance to blood clotting,
     resistance to bacterial colonization, and
     normal, uncomplicated healing.




                                                  19/68
               Biocompatibility
   This general concept of biocompatibility
    has been extended recently in the broad
    approach called "tissue engineering"
       careful selection of cells, materials, and
        metabolic and biomechanical conditions to
        regenerate functional tissues.




                                                20/68
Classic Examples of
    Biomaterials




                      21
Classic Examples: Table 1
         (Ratner)




                            22/68
Classic Examples: Table 1 (Ratner)




                                23/68
Classic Examples: Table 1 (Ratner)




                                24/68
 Biomaterials and
health care market




                     25
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              Classic Examples
   Substitute Heart
    valves: Heart valve
    prostheses are fabricated
    from carbons, metals,
    elastomers, fabrics and
    natural (e.g. pig) valves and
    other tissues chemically
    pretreated to reduce their
    immunologic reactivity and
    enhance durability.
   Problem: degeneration of
    tissue, mechanical failure,
    postoperative infection, and
    induction of blood clot.

                                    28/68
             Classic Examples
   Artificial Hip Joint: The
    human hip joint is subjected to
    high mechanical stress and
    undergoes considerable
    abuse.
   Hip joints are fabricated from
    specific high-strength alloy,
    ceramics, composites, and
    ultrahigh molecular weight
    polyethylene.
   In most cases, good function
    is restored, and even athletic
    activities are possible.
   After 10-15 years, the implant
    may loosen, necessitating
    another operation.                29/68
             Classic Examples
   Dental implant:
    Titanium implants, which
    form an artificial tooth
    root on which crown is
    affixed.
   A special requirement of
    a material in this
    application is the ability
    to form a tight seal
    against bacterial
    invasion where the
    implant traverses the
    gingival (gum).
                                 30/68
            Classic Examples
   Intraocular Lenses:
    Intraocular Lenses
    (IOLs) made by poly
    (methyl methacrylate),
    silicone elastomer, or
    other materials are
    used to replaced a
    natural lens when it
    become cloudy and
    cataractous.


                               31/68
    Characteristics of Biomaterials
               Science
 Multidisciplinary
 Many diverse materials
 Development of biomaterials devices
 Magnitude of the field
 Success and failure




                                        32/68
    Characteristics of Biomaterials
        Science: Multidisciplinary
   More than any other field of contemporary
    technology, biomaterials science brings
    together researchers from diverse
    backgrounds who must communicate
    clearly.
   Figure 6 lists some of the disciplines that are
    encountered in the progression from
    identifying the need for a biomaterial or
    device to its manufacture, sale, and
    implantation.
                                                 33/68
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        Many Diverse Materials:
 The biomaterials scientist will have an
  appreciation of materials science.
 This may range from
     an impressive command of the theory and
     practice of the field demonstrated by the
      professional materials scientist to
     a general understanding of the properties of
      materials that might be demonstrated by the
      physician or biologist investigator involved in
      biomaterials-related research.
                                                    35/68
    Many Diverse Materials:
   A wide range of materials is routinely
    used and no one researcher will be
    comfortable synthesizing and designing
    with all these materials.




                                         36/68
       Many Diverse Materials:
   Hard tissue replacement biomaterials: metals,
    ceramics, used in orthopedic and dental
    materials.
   Soft tissue replacement biomaterials: polymers,
    cardiovascular and general plastic surgery
    materials.
   Some devices involved both soft and hard tissue.
   There is need for a general understanding of all
    class of materials.

                                                 37/68
    Development of biomaterials
          devices: Fig 6.
       It provides a perspective on how
        different disciplines work together,
         starting from the identification of a need for
          a biomaterial through
         development,
         manufacture,
         implantation, and
         removal from the patient.

                                                       38/68
Characteristics of Biomaterials
              Science




                              39/68
      Magnitude of the field.
   Magnitude expresses both a magnitude
    of need and magnitude of a commercial
    market.
   Needless to say, a conflict of interest can
    arise with pressure from both the
    commercial quarter and from the ethical
    consideration.


                                             40/68
            Success and Failure
   Most biomaterials and medical devices perform
    satisfactorily, improving the quality of life for the
    recipient or saving lives.
   However, no manmade construct is perfect.
   All manufactured devices have a failure rate.
   Also, all humans are different with differing
    genetics, gender, body chemistries, living
    environment, and degrees of physical activity.
   Furthermore, physicians implant or use these
    devices with varying degrees of skill.
                                                        41/68
            Success and Failure
   The other side to the medical device success
    story is that there are problems, compromises,
    and complications that occur with medical
    devices.
   Central issues for the biomaterials scientist,
    manufacturer, patient, physician, and attorney
    are,
    (1) what represents good design,
    (2) who should be responsible when devices perform "
      with an inappropriate host response," and
    (3) what are the cost/risk or cost/benefit ratios for the
      implant or therapy?

                                                            42/68
           Success and Failure
   Some examples may clarify these issues.
   Clearly, heart valve disease is a serious medical
    problem. Patients with diseased aortic heart
    valves have a 50 % chance of dying within 3
    years.
   Surgical replacement of the diseased valve
    leads to an expected survival of 10 years in 70
    % of the cases.
   However, of these patients whose longevity and
    quality of life have clearly been enhanced,
    approximately 60 % will suffer a serious valve-
    related complication within 10 years after the
    operation.
                                                   43/68
 Subjects Integral to
Biomaterials Science




                        44
         Subjects Integral to
        Biomaterials Science
   Toxicology
   Biocompatibility
   Functional tissue structure and
    pathobiology
   Healing
   Dependence on specific anatomical site
   Mechanical and Performance requirements:
   Industrial involvement
   Ethics (Table 3)
   Regulation

                                          45/68
              Toxicology:
   It deals with the substances that migrate
    out of biomaterials. Ex: for polymers,
    many low-molecular-weight “leachables”
    exhibit some level of physiologic activity
    and cell toxicity.
   It is reasonable to say that a biomaterial
    should not give off anything from its
    mass unless it is specifically designed to
    do so.

                                            46/68
           Biocompatibility:
   The understanding and measurement of
    biocompatibility is unique to biomaterials
    science.
   Unfortunately, we do not have precise
    definitions or accurate measurements of
    biocompatibility.
   It is defined in terms of performance or
    success at a specific task.
   However, this operational definition offers us
    little to use in designing new or improved
    vascular prostheses.
   In fact, biocompatibility may have to be
    uniquely defined for each application.
                                                     47/68
     Functional tissue structure and
             pathobiology
     Biomaterials incorporated into medical devices
      are implanted into tissues and organs.
     Critical considerations to workers in the field.
1.    The key principles governing the structure of
      normal and abnormal cells, tissues, and
      organs,
2.    the techniques by which the structure and
      function of normal and abnormal tissue are
      studied, and
3.    the fundamental mechanisms of disease
      processes

                                                    48/68
                   Healing
   Injury to tissue will stimulate the well define
    inflammatory reaction sequence that lead to
    healing.
   When a foreign body is involved, the reaction
    sequence is referred to as “foreign body
    reaction”.
   The normal response of body will be
    modulated because of the solid implant.
   This reaction will differ in intensity and
    duration depending upon the anatomical sites
    involved.

                                                  49/68
      Dependence on specific
         anatomical site:
   Each site challenges the biomedical
    device designer with special
    requirements for geometry, size,
    mechanical properties, and bioreaction.




                                          50/68
    Mechanical and Performance
          requirements:
    Each biomaterial and device has imposed
     upon in mechanical and performance
     requirements that originate from the physical
     (bulk) properties of the material.
    These requirements can be divided into three
     categories:
     mechanical performance,
     mechanical durability, and
     physical properties (functional).

                                                 51/68
      Industrial involvement
   The balance between the desire to
    alleviate loss of life and suffering, and
    the corporate imperative to turn a profit
    force us to look further afield (out of the way)
    for guidance.




                                                  52/68
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                     Ethics (1)
   Is the use of animals justified? Specifically, is the
    experiment well designed and important so that
    the data obtained will justify the suffering and
    sacrifice of the life of a living creature?

   How should research using humans be
    conducted to minimize risk to the patient and
    offer a reasonable risk-to-benefit ratio? How can
    we best ensure informed consent?

                                                      54/68
                      Ethics (2)
   Companies fund much biomaterials research and own
    proprietary biomaterials.
   How can the needs of the patient be best balanced with
    the financial goals of a company?
   Consider that someone must manufacture devices - -
    these would not be available if a company didn’t choose
    to manufacture them.

   Since researchers often stand to benefit financially from
    a successful biomedical device and sometimes even
    have devices named after them, how can investigator
    bias be minimized in biomaterials research?
                                                            55/68
                    Ethics (3)
   For life-sustaining devices, what is the
    trade-off between sustaining life and the
    quality of life with the device for the
    Patient? Should the Patient be permitted
    to "Pull the plug" if the quality of life is not
    satisfactory?



                                                   56/68
                  Ethics (4)
   With so many unanswered questions
    about the basic science of biomaterials, do
    government regulatory agencies have
    sufficient information to define adequate
    tests for materials and devices and to
    properly regulate biomaterials?



                                             57/68
                  Ethics (5)
   Should the government or other "third-
    party payers" of medical costs pay for the
    health care of patients receiving devices
    that have not yet been formally approved
    for general use by the FDA and other
    regulatory bodies?



                                             58/68
                               Ethics (6)
    Should the CEO of a successful multimillion
     dollar company that is the sole manufacturer a
     polymer material (that is a minor but crucial
     component of the sewing ring of nearly all heart
     valves ) yield to the stockholders, demands that
     he/she terminate the sale of this material
     because of litigation concerning one model of
     heart valve with a large cohort of failures?
    The company sells 32 Pounds of this material
     annually, yielding revenue of approximately $40,
     000?
                                                                                  59/68
    Cohort: a group of individuals having a statistical factor (as age or class
                  Ethics (7)
   Should an orthopedic appliance company
    manufacture two models of hip joint
    prostheses: one with an expected "lifetime”
    of 20 years ( for young, active recipients )
    and another that costs one-fourth as much
    with an expected lifetime of 7 years ( for
    elderly individuals ), with the goal of saving
    resources so that more individuals can
    receive the appropriate care?

                                                60/68
                Regulation
   To prevent inadequately tested devices and
    materials from coming on the market, and to
    screen out individuals clearly unqualified to
    produce biomaterial, a complex national
    regulatory system has been erected by the
    United States government through the Food
    and Drug Administration (FDA).
   Through the International Standards
    Organization (ISO), international regulatory
    standards have been developed for the world
    community.
                                                61/68
              Regulation
 The cost to meet the standards and to
  demonstrate compliance with material,
  biological, and clinical are enormous.
 Introducing a new biomedical device to the
  market require a regulatory investment of
  many millions dollars.
 Are the regulations and standards truly
  addressing the safety issue ?
                                          62/68
               Regulation
 Is the cost of regulations inflating the cost
  of health care and preventing improved
  devices from those who need them?
 Under this regulation topic, we see the
  interaction of all the players in the
  biomaterials community: government,
  industry, ethics and basic science.


                                              63/68
              Summary:
   A broad overview of the biomaterials
    field. It provides a vantage point from
    which the reader can gain a perspective
    to see how the sub-themes fit into the
    larger whole.
   Biomaterials science may be the most
    multidisciplinary all the sciences.


                                         64/68
                  Summary:
   Consequently, biomaterials scientists must
    master certain key material from many fields of
    science, technology, engineering, and medicine
    in order to be competent and conversant in this
    profession.
   The reward for mastering this volume of material
    is immersion in an intellectually stimulating
    endeavor that advances a new basic science of
    biointeraction and contributes to reducing
    human suffering.
                                                  65/68
                 Summary:
 Basic definition of biomaterials
 Example of biomaterials application
 Characteristics of biomaterials Science
     Multidisciplinary
     Many diverse materials
     Development of biomaterials Devices
     Magnitude of the field
     Success and failure

                                            66/68
                     Summary:
   Subjects Integral to Biomaterials Science
       Toxicology:
       Biocompatibility
       Functional tissue structure and pathobiology
       Healing:
       Dependence on specific anatomical site
       Mechanical and Performance requirements:
       Industrial involvement:
       Ethics (Table 3)
       Regulation
                                                       67/68
                   Home work I:
            Due: Next week (9/20/2010)
I.     Find an abstract from the least issue of “Biomaterials”
       and write your opinion about this paper. (100-300
       words) (30%)
II.    End Note: Following question I, copy the text of
       Introduction or Discussion with 10-20 references from
       that paper and use End Note to cite these reference.
       Build a End Note file for these reference. (45%)
III.   What is your opinion about the ethical concerns
       related to biomaterials science? Please answer “one”
       of the issues from Table 3 (in page 8). Choose
       anyone from that table. (25 %) (100-300 words)


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   Some helpful dictionary sites:
       http://www.m-w.org/
       http://dictionary.reference.com/
       http://dict.vghtpe.gov.tw/search.php
       http://tw.dictionary.yahoo.com/
       http://www.hk-doctor.com/html/dict.php ????
       http://www.google.com.tw/




                                                      70/68
To be continued…….




                     71
           Success and Failure
   Another example involves LVADs.
   A clinical trial called Randomized Evaluation of
    Mechanical Assistance for the Treatment of
    Congestive Heart Failure (REMATCH) led to the
    following important statistics (Roseetal., 2001).
   Patients with an implanted Heartmate LVAD
    (Thoratec Laboratories) had a 52 % chance of
    surviving for 1 year, compared with a 25 %
    survival rate for patients who took medication.
   Survival for 2 years in patients with the
    Heartmate was 23 % versus 8 % in the
    medication group.
                                                   72/68
           Success and Failure
   Also, the LVAD enhanced the quality of life for
    the patients 一 they felt better, were less
    depressed, and were mobile.
   Importantly, patients participating in the
    REMATCH trial were not eligible for a heart
    transplant.
   In the cases of the heart valve and the LVAD,
    long 一 term clinical complications associated
    with imperfect performance of biomaterials do
    not preclude clinical success overall.

                                                      73/68
                Success and Failure
   These five characteristics of biomaterials
    science : (1)multidisciplinary, (2)multimaterial,
    (3)need-driven, (4)substantial market, and
    (5)risk-benefit, flavor all aspects the field.
   In addition, there are certain subjects that are
    particularly prominent in our field and help
    delineate biomaterials science as a unique
    endeavor · Let us review a few of these.


to describe, portray, or set forth with accuracy or in detail
                                                                74/68

				
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