Questions and Answers
What is a biomaterial?
A synthetic material used to replace part of living systems or to function in intimate contact with living tissue.
What distinguishes biomaterials from biological materials?
Biomaterials are synthetic, while biological materials are produced by living organisms.
All synthetic materials that come in contact with the skin are classified as biomaterials.
False
What was one of the first uses of biomaterials?
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What materials were introduced in the 1930s that led to greater success in fracture fixation?
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Biomaterials can be classified based on their origin into __________ and __________.
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Which of the following is a characteristic of biodegradable polymers?
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What type of biomaterials exhibit specific interactions with surrounding tissue?
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What is nanofabrication?
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What was one of the first clinical applications of ceramics?
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Study Notes
Biomaterials
Introduction
- Biomaterials are synthetic materials used to replace or function in intimate contact with living tissue.
- Biomaterials are not the same as biological materials, which are produced by a living organism.
- Examples of biomaterials include artificial joints, implantable devices, and contact lenses.
Historical Background
- The practical use of biomaterials began in the 1860s with the promotion of aseptic surgical techniques.
- Early biomaterials were focused on the skeletal system (orthopedic) and were primarily made of bone plates and stainless steel.
- In the 1930s, cobalt chromium alloys were introduced, leading to greater success in fracture fixation and joint replacement surgery.
- After World War II, plastics and polymers were introduced as biomaterials due to their successful use in aircraft canopies.
1st Generation Biomaterials
Characteristics
- Designed for use inside the human body.
- Applied in multiple disciplines of medicine, including orthopedics, cardiovascular surgery, ophthalmology, and wound healing.
- Made from commonly available materials.
Examples
- Cellulose acetate: used to make early dialysis tubes.
- Dacron: used as early vascular grafts.
Biocompatibility and Biofunctionality
Biocompatibility
- Refers to the acceptance of an artificial implant by the surrounding tissue and the body as a whole.
- A completely biocompatible material would not cause inflammatory responses, toxicity, or carcinogenic effects.
Biofunctionality
- Refers to a biomaterial's ability to exhibit physical and mechanical properties to augment or replace body tissue.
Classifying Biomaterials
Natural Vs. Synthetic Biomaterials
- Natural biomaterials: derived from non-human origin, such as cellulose, silk, and natural rubber.
- Synthetic biomaterials: man-made materials, such as metals, alloys, ceramics, and polymers.
Metals and Alloys
Characteristics
- Commonly used for load-bearing implants, such as orthopedic and dental implants.
- May corrode over time, releasing harmful substances into the surrounding tissue.
Examples
- Pure metals: gold, silver, platinum, and titanium.
- Alloys: stainless steel, titanium alloys, and cobalt-based alloys.
Ceramics
Characteristics
- Polycrystalline compounds, including silicates, metallic oxides, carbides, and refractory hydrides, sulfides, and selenides.
- Generally brittle and have low tensile strength.
Examples
- Bioinert ceramics: alumina, zirconia, and silicon nitrides.
- Bioreactive ceramics: glass, glass ceramic, calcium phosphate-based materials.
- Biodegradable ceramics: aluminum calcium phosphate, coralline, and plaster of Paris.
Polymers
Characteristics
- Consist of small repeating units (monomers) joined together to form long chain molecules.
- Properties can be altered by changing molecular weight, substituting backbone carbon, or adding side chains or cross-linking.
Examples
- Polyvinyl chloride (PVC), polymethylmethacrylate (PMMA), polyesters, and polyamides/nylons.
Composites
Characteristics
- Composed of two or more distinct materials, achieving desired physical and chemical properties.
- Examples: rubber catheter filled with silica particles to enhance strength and toughness.
2nd Generation Biomaterials
Characteristics
- Focus on bioactive and biodegradable properties.
- Exhibit specific and controlled interaction with surrounding tissue.
Examples
- Biodegradable polymers: polyglycolic acid, polylactic acid, polycaprolactone, and poly(ortho)esters.
- Hydrogels: cross-linked hydrophilic polymer networks that can absorb water or biological fluids.
3rd Generation Biomaterials
Characteristics
- Both biodegradable and bioactive.
- Aid regeneration, not only replacement, of injured or lost tissue.
- Use nanofabrication and microfabrication techniques.
Examples
- Tissue engineering: creating living, physiological, three-dimensional tissues and organs.
- Immunoisolation barrier for encapsulated cells.
Nanotechnology and Biomaterials
Characteristics
- Nano fabrication refers to the process and methods employed in creating nanoscale materials and structures.
- Techniques include top-down and bottom-up fabrication methods.
Examples
- Dental fillings: nanocomposite materials containing nanoparticles of silica or other reinforcing agents.
- Diagnostic imaging: iron oxide nanoparticles as contrast agents in magnetic resonance imaging (MRI).
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Description
This quiz covers the basics of biomaterials, including their historical background, generations, and applications. It's perfect for students and professionals in the field of biomedical engineering.
