Chapter 12 Biomaterials Flashcards
What is Biomaterials?
A substance that has been engineered to interact with biological systems for a medical purpose either therapeutic or a diagnostic one
What is Biocompatibility
Ability of a material to perform with an appropriate host responds for specific application
How does Biocompatibility primarily work?
It is a surface phenomenon where upon contact with host tissues, the surface of the biomaterial is coated with blood and plasma proteins layer.
Also known as the Vroman effect
What is the difference between adsorption and absorption?
Adsorption:
Particles stick to the surface of the other interface
Absorption:
Particles soak into the bulk of other interface
How does the cell form attachment of biomaterial surface?
1) Initial contact with material will form bonds between cell surface receptors and cell adhesion ligands which is on the material surface
2) The cell reorganizes with progressive spreading of the cell on the material to increase the strength of attachment
3) Cell binding is mediated by mechanical forces and change in cell shape
4) Cells then interact with the adsorb proteins on the surface and not with material directly
5) The more cells spread, the higher the rate of proliferation
What are the 10 Examples of a Biomaterial Application
1) Artificial ligaments/tendons/skin
2) Biosensors and filtration
3) Bone cement
4) Bone plates
5) Cardiovascular stents/valves
6) Cochlear replacements
7) Contact lenses
8) Dental implants
9) Drug delivery/tissue engineering
10) Joint replacements
Name 5 Biomaterials companies
1) Baxter International
2) Carmeda
3) Howmedica
4) Medtronic
5) Zimmer
What is tissue engineering?
A field that applies the principles of engineering and life sciences towards development of biological substitutes that restore, maintain or improve tissue function
What is a potential scenario of tissue engineering?
1) Patient receives cells from doner or his own, which is incorporated into 3D scaffolds of biodegradable polymers
2) The entire structure of cells and scaffolding is transplanted into wound site
3) Cells replicated and reorganize to form new tissue
4) Artificial polymer break down leaving a completely natural final product which is a neo organ
What does a Scaffold do?
1) Provides structural support and shape
2) Provides a place for cell attachment and growth
3) Usually biodegradable and biocompatible
4) Not intended to stay in the system forever
What are the 6 design criteria for scaffolds
1) Appropriate mechanical and physical properties
2) Promotes cell adhesion
3) Proper degradation rate
4) Does not produce toxic degradation products
5) Integration into surrounding native tissue
6) Minimal inflammatory/immune response
What are the 4 types of Scaffold Materials
1) Polymeric (chitosan, alginate; hydrogels)
2) Natural (collagen, elastin, fibrin; hydrogels)
3) Ceramic (calcium phosphate; porous structures)
4) Permanent verses resorbable (degradation by hydrolysis)
What is Host Response?
The local or systemic response of the host on the material
What is Material response?
The response of the material to the living system
What are 6 examples of Local Host response?
local = at the site of implantation
1) Protein adsorption
2) Coagulation of blood
3) Platelet adhesion to biomaterials
4) Hemolysis (blood damage)
5) Inflammation
6) Infection
What are the 6 example of Systemic Host response
systemic = throughout the whole body
1) Thrombus formation (blood clot)
2) Embolization (tiny moving particles in blood vessels)
3) Hypersensitivity
4) Elevation of implant elements in blood (cancer causing)
5) Lymphatic particle transport to other tissues/organs
6) Systemic toxicity
What is the limitation of Artificial Skin as of now?
None of the artificial skin and tissue engineering technology can replicate or regenerate the function of skin appendages like hair follicles and sweat glands
What is a Bioreactor?
It is to mimic the in-vivo conditions as to what actually happens inside the body and it’s conditions to help cells grow and proliferate
What are the 4 main ways material can interact with the human body?
1) It can hurt you.
2) It can dissolve and be replaced by cells.
3) Your body can surround it with a protective layer.
4) It can bond with your living tissue.
What are the 4 modern biomaterials?
1) Titanium (dental implants and pace maker)
2) Stainless Steel (joint replacements)
3) Polyurethane (catheters, artificial heart valves)
4) Hydrogels (contact lenses, drug delivery)
What is a biologically inert material?
It means that the material causes little or no reaction with nearby tissues, your body may recognize them as foreign materials and try to surround them in fibrous tissue, but doesn’t outright reject them.
Why is titanium a superior biomaterial compared to stainless steel?
Because it is more biocompatible with the body as it lacks things like nickel which can sometimes cause allergic reactions in people. It also has a lower density compared to other metallic biomaterials, so titanium implants will be lighter than a similar one made from stainless steel.
What is the reason for coating titanium with biological materials?
(such as blood thinners, proteins and silver)
1) It is used for implants to help prevent blood clots.
2) Collagen-based protein: might help to speed up healing process.
3) Protein: gives the alloy the ability to bond with living tissues and discourage bacterial growth.
What are some characteristics of polyurethane that make it a useful biomaterial?
It has a high level of elasticity, so it is pretty flexible, but it is also durable and resistant to tearing which performs well under both static and dynamic load.
What characteristics of hydrogels enable it to retain water?
Hydrophilic structures which are cross-linked polymers capable of holding large amount of water. They are basically polymers that create a net shaped structure which give the material the property to retain water.
Why is PHEMA suitable for making contact lens? What else can it be used for?
Because it is unreactive and supportive of biological processes. It is also tough, does not degrade easily, is not absorbed by the body, and can take on many different shapes and forms which makes it a kind of Swiss army knife of biomaterials. Hence, these characteristics make PHEMA a suitable material for making contact lenses.
It can also be used for drug delivery.
what are 4 other applications of hydrogels?
1) Wound-healing bio adhesives.
2) Artificial skin and cartilage
3) Sexual organ reconstruction
4) Vocal cord replacements
