BIOMATERIALS in Medicine Titik Nuryastuti MIcrobiology Department, Fac. of Medicine Universitas Gadjah Mada

INTRODUCTION A biomaterial is a nonviable material used in a medical device, intended to interact with biological systems. is used to make devices to replace a part of a function of the body in a safe, reliable, economic, and physiologically acceptable manner. is any substance (other than a drug), natural or synthetic, that treats, augments, or replaces any tissue, organ, and body function. The need for biomaterials stems from an inability to treat many diseases, injuries and conditions with other therapies or procedures : replacement of body part that has lost function (total hip, heart) correct abnormalities (spinal rod) improve function (pacemaker, stent) assist in healing (structural, pharmaceutical effects: sutures, drug release)

HISTORY Important dates 1860's: Lister develops aseptic surgical technique early 1900's: Bone plates used to fix fractures 1930's: Introduction of stainless steel, cobalt chromium alloys 1938 : first total hip prosthesis (P. Wiles) 1940's: Polymers in medicine: PMMA bone repair; cellulose for dialysis; nylon sutures 1952: Mechanical heart valve 1953: Dacron (polymer fiber) vascular grafts 1958: Cemented (PMMA) joint replacement 1960: first commercial heart valves 1970's: PEO (polyethyleneoxide) protein resistant thin film coating 1976: FDA ammendment governing testing & production of biomaterials /devices 1976: Artificial heart (W. Kolff)

EXAMPLES OF USES OF BIOMATERIALS B. Amsden CHEE 340

MATERIAL ATTRIBUTES FOR BIOMEDICAL APPLICATIONS

BIOCOMPATIBILITY There is no general set of criteria, that if met, qualify a material as being biocompatible The time scale over which the host is exposed to the material or device must be considered 6

Classes of Biomaterials Metals stainless steel, cobalt alloys, titanium alloys Ceramics aluminum oxide, zirconia, calcium phosphates Polymers silicones, poly(ethylene), poly(vinyl chloride), polyurethanes, polylactides Natural polymers collagen, gelatin, elastin, silk, polysaccharides

Material Properties OBJECTIVES To introduce the fundamental mechanical and surface chemistry properties of biomaterials OUTLINE Mechanical Properties elasticity, viscoelasticity, brittle fracture, fatigue Surface chemistry 8

Mechanical Properties Many applications require the biomaterial to assume some of the applied load on the body part. s e tension shear 9

Viscoelasticity The response of materials to an imposed stress may under certain conditions resemble the behavior of a solid or a liquid. Stress Relaxation (application of a sudden strain to the sample and following the stress as a function of time as the strain is held constant). Creep (a constant stress is instantaneously applied to the material and the resulting strain is followed as a function of time) 10

Surface Energy Interface significance boundary between 2 layers protein adsorption to materials blood coagulation/thrombosis due to material contact cellular response to materials 11

Surface Chemistry At the surface (interface) there are intermolecular forces and intramolecular forces of attraction and repulsion. van der Waals forces : Hydrogen Bonds : Coulombic : B. Amsden CHEE 340 12

Surface Electrical Properties surface may become charged by adsorption of ionic species present in sol’n or preferential adsorption of OH- ionization of -COOH or -NH2 group + - + - + - + - + - + hydroxyl ion - solid 13

Surface Energy and the Contact Angle q gLV gSL gSV 14

Bacterial Adhesion to Biomaterials 9/9/2018 15

Definition: Biomaterial 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. In your opening, establish the relevancy of the topic to the audience. Give a brief preview of the presentation and establish value for the listeners. Take into account your audience’s interest and expertise in the topic when choosing your vocabulary, examples, and illustrations. Focus on the importance of the topic to your audience, and you will have more attentive listeners. 9/9/2018 16 16

Applications of Biomaterials Orthopedics: artificial hips,knees, shoulders, wrists; intervertebral discs; fracture fixation; bone grafts. Cardiovascular: heart valves, PTCA balloons, pacemakers, catheters, grafts, stents. Dental: enamels, fillings,prosthetics, orthodontics. Soft tissue: wound healing, reconstructive and augmentation, occular. Surgical: staples, sutures, scalpels. 17

Orthopedic Implants Also most common Surgical technique well established Obvious biocompatibility, good ingrowth Evidence is mounting for Tendon harvesting – Volleyball players not runners Harvest site morbidity and pain from harvesting 18

Cardiovascular devices 19

Therapeutic Devices in Orthopedics Approximately 245,000 knee replacements are done annually in the United States, and this number is expected to grow rapidly as the population ages. 9/9/2018 20 20

Applications in Dentistry 9/9/2018 21 21

Catheters 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. 9/9/2018 22 22

In Ophthalomolgy 9/9/2018 23 23

In Nephrology 9/9/2018 24 24

In Drug Delivery 9/9/2018 25 25

Future Applications- Tissue Replacement 9/9/2018 26 26

General Applications of Biomaterials Storage of fluids, tissues, and other biological products Diagnosis Monitoring Therapy 9/9/2018 27 27

Definition: Biomaterial -FDA "an instrument, apparatus, implement, machine, contrivance, implant, in vitro reagent, or other similar or related article, including a component part, or accessory which is recognized in the official National Formulary, or the United States Pharmacopoeia, or any supplement to them, intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment, or prevention of disease, in man or other animals, or intended to affect the structure or any function of the body of man or other animals." 9/9/2018 28 28

Classification of Medical Devices Based on the duration of the device use, invasiveness and risk to the user. Class I devices: crutches, bedpans, tongue depressors, adhesive bandages etc. –minimal invasiveness, does not contact the user internally. Class II devices: hearing aids, blood pumps, catheters, contact lens, electrodes etc. –higher degree of invasiveness and risk, but relatively short duration. Class III devices: cardiac pacemakers, intrauterine devices, intraocular lenses, heart valves, orthopedic implants, etc. -considerably more invasive and can pose immense risk to the user-implantables. 9/9/2018 29 29

Biocompatibility testing include procedures designed to evaluate: cytotoxicity; acute, subchronic, and chronic toxicity; irritation to skin, eyes, and mucosal surfaces; sensitization; hemocompatibility; short-term implantation effects; genotoxicity; carcinogenicity; and effects on reproduction, including developmental effects. 9/9/2018 30

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