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Dr. Alagiriswamy A A , (M.Sc, PhD, PDF) Asst. Professor (Sr. Grade), Dept. of Physics, SRM-University, Kattankulathur campus, Chennai. ABCs of Biomaterials. UNIT III Lecture 1. before i proceed. I refer you to read out this handbook Available in our SRM library Totally three copies
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Dr. Alagiriswamy A A, (M.Sc, PhD, PDF) Asst. Professor (Sr. Grade), Dept. of Physics, SRM-University, Kattankulathur campus, Chennai ABCs of Biomaterials UNIT III Lecture 1
before i proceed • I refer you to read out this handbook • Available in our SRM library • Totally three copies • Out of three, only one is reference type • Author Information • By Dr. Buddy D. Ratner,; School of Dentistry and Medicine, University of Alabama, Birmingham, U.S.A. "The most thorough textbook available, covering most aspects of biomaterials science … provides the most up-to-date and in-depth information on biomaterial developments." --MRS Bulletin, January 2006
More than a multi-disciplinary Field • Bioengineers • Material Scientists • Immunologists • Chemists • Biologists • Surgeons • others
A Little History on Biomaterials • Romans, Chinese, and Aztecs used gold in dentistry over 2000 years ago, Cu not good. • Ivory & wood teeth • Aseptic surgery 1860 (Lister) • Bone plates 1900, joints 1930 • Turn of the century, synthetic plastics came into use • WWII, shards of PMMA unintentionally got lodged into eyes of aviators • Parachute cloth used for vascular prosthesis • 1960- Polyethylene and stainless steel being used for hip implants
Background • During the last two decades, significant advances have been made in the development of biocompatibleand biodegradable materials for medical applications. • In the biomedical field, the goal is to develop and characterize artificial materials or, in otherwords, “spare parts” for use in the human body to MEASURE, RESTORE and IMPROVE physical functions and enhance survival and quality of life
CLASSIFICATION OF BIOMATERIALS • First generation: INERT • Do not trigger any reaction in the host: neither rejected nor recognition • “do not bring any good result” • Second generation: BIOACTIVE • Ensure a more stable performance in a long time or for the period you want • Third generation: BIODEGRADABLE • It can be chemically degraded or decomposed by natural effectors (weather, soil, bacteria, plants, animals)
BIOMATERIALS • Biomaterials science may be the MOST multidisciplinary of all the sciences which encompasses aspects of medicine, biology, chemistry, engineering and materials science. • Biomaterials are : “Non-viable materials used in a medical devices intended to interact with biological systems” [D.F. Williams, 1987] • Non-viable : - incapable of growing and developing independently What do you mean by the term "Most" ?
What is the definition of a Biomaterial ? • Casual definition: • A BIOMATERIAL is a synthetic material used to replace part of a living system or to function in intimate contact with living tissue. • Formal definition by Clemson University Advisory Board for Biomaterials: • A BIOMATERIAL is a systemically and pharmacologically inert substance designed for implantation within or incorporation with living systems.
Success of biomaterials: • Dependent on factors engineers/scientists can control: • Choice of material • Geometric design • Synthesis or manufacturing of biomaterial • Dependent on factors engineers/scientists cannot control: • Surgical technique • Health and condition of patient • Post-surgical activities by patient
Variable Pore Size in Bone Is it interesting ???? 4µm 220µm
Micro-evaluation of biomaterials • Define reliability (r) & probability of biomaterial failure (f): r = 1 – f • May have multiple modes of failure based on: • Body infection • Implant toxicity • Inflammation of immune response • Mechanical failure (strength, stiffness, and fatigue) • Optical/Electrical properties • Diffusion properties • Manufacturability • Density • Geometric design Thus, total reliability (rt) is given by product of individual reliabilities [r1 = (1-f1)] : rt = r1r2 • • • • rn
Biomaterials may be considered as metals, ceramics, polymers, or composites:
Bio-technical terms • BIOFUNCTIONALITY • Playing a specific function in physical and mechanical terms • BIOCOMPATIBILITY • Concept that refers to a set of properties that a material must have to be used safely in a biological organism • Synthetic or natural material used in intimate contact with living tissue (it can be implanted, partially implanted or totally external). • Biocompatible materials are intended to interface with biological system to EVALUATE, TREAT, AUGMENT or REPLACE any tissue, organ or function of the body • Biocompatible material features • Absence of carcinogenicity (the ability or tendency to produce cancer) • Absence of immunogenic (absence of a recognition of an external factor which could create rejection) • Absence of teratogenicity (ability to cause birth defects) • Absence of toxicity
Biocompatibility is primarily a surface phenomenon … Testing specimens • Rabbits – ear, skin, pyrogen • Guinea Pigs – skin, esp C@ • Mice – genotoxicity • Horseshoe Crab – endotoxins • Pig – implant • Bacteria - genotoxicity • Test actual & elutants & extracts… • People – long term
Some more BIO-TECHNICAL terms • Bioactivity - Evolving concept: • The characteristic that allows the material to form a bond with living tissue (Hench, 1971) • The ability of a material to stimulate healing and trick the tissue system into responding as if it were a natural tissue (Hench 2002). • Advantages: Bone tissue – implant interface, enhanced healing response, extends implant life • Biodegradability: • Breakdown of implant due to chemical or cellular actions • If timed to rate of tissue healing transforms implant to scaffold for tissue regeneration • Negates issues of stress shielding, implant loosening, long term stability what about biodurability, bioavailability, bioinert ?????????????
Some examples of biomaterials Where is chitra Triunal (trivandrum)??
Understanding the ideas of each lecture REQUIRES the knowledge of the previous lectures. In the past, people who have skipped a lot of classes have received very bad grades. Conversely, people who’ve come to most or all of the classes nearly always receive A’s and B’s. Find out the secrets of how to become a rich or a fast learner ????????? If you keep up, you won’t end up looking like this hour before the commencement of the classes.