Chapter 12 Biomaterials

Question 1

What is Biomaterials?

Answer 1

A substance that has been engineered to interact with biological systems for a medical purpose either therapeutic or a diagnostic one

Question 2

What is Biocompatibility

Answer 2

Ability of a material to perform with an appropriate host responds for specific application

Question 3

How does Biocompatibility primarily work?

Answer 3

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

Question 4

What is the difference between adsorption and absorption?

Answer 4

Adsorption:

Particles stick to the surface of the other interface

Absorption:

Particles soak into the bulk of other interface

Question 5

How does the cell form attachment of biomaterial surface?

Answer 5

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

Question 6

What are the 10 Examples of a Biomaterial Application

Answer 6

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

Question 7

Name 5 Biomaterials companies

Answer 7

1) Baxter International
2) Carmeda
3) Howmedica
4) Medtronic
5) Zimmer

Question 8

What is tissue engineering?

Answer 8

A field that applies the principles of engineering and life sciences towards development of biological substitutes that restore, maintain or improve tissue function

Question 9

What is a potential scenario of tissue engineering?

Answer 9

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

Question 10

What does a Scaffold do?

Answer 10

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

Question 11

What are the 6 design criteria for scaffolds

Answer 11

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

Question 12

What are the 4 types of Scaffold Materials

Answer 12

1) Polymeric (chitosan, alginate; hydrogels)
2) Natural (collagen, elastin, fibrin; hydrogels)
3) Ceramic (calcium phosphate; porous structures)
4) Permanent verses resorbable (degradation by hydrolysis)

Question 13

What is Host Response?

Answer 13

The local or systemic response of the host on the material

Question 14

What is Material response?

Answer 14

The response of the material to the living system

Question 15

What are 6 examples of Local Host response?

local = at the site of implantation

Answer 15

1) Protein adsorption
2) Coagulation of blood
3) Platelet adhesion to biomaterials
4) Hemolysis (blood damage)
5) Inflammation
6) Infection

Question 16

What are the 6 example of Systemic Host response

systemic = throughout the whole body

Answer 16

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

Question 17

What is the limitation of Artificial Skin as of now?

Answer 17

None of the artificial skin and tissue engineering technology can replicate or regenerate the function of skin appendages like hair follicles and sweat glands

Question 18

What is a Bioreactor?

Answer 18

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

Question 19

What are the 4 main ways material can interact with the human body?

Answer 19

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.

Question 20

What are the 4 modern biomaterials?

Answer 20

1) Titanium (dental implants and pace maker)
2) Stainless Steel (joint replacements)
3) Polyurethane (catheters, artificial heart valves)
4) Hydrogels (contact lenses, drug delivery)

Question 21

What is a biologically inert material?

Answer 21

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.

Question 22

Why is titanium a superior biomaterial compared to stainless steel?

Answer 22

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.

Question 23

What is the reason for coating titanium with biological materials?
(such as blood thinners, proteins and silver)

Answer 23

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.

Question 24

What are some characteristics of polyurethane that make it a useful biomaterial?

Answer 24

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.

Question 25

What characteristics of hydrogels enable it to retain water?

Answer 25

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.

Question 26

Why is PHEMA suitable for making contact lens? What else can it be used for?

Answer 26

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.

Question 27

what are 4 other applications of hydrogels?

Answer 27

1) Wound-healing bio adhesives.

2) Artificial skin and cartilage

3) Sexual organ reconstruction

4) Vocal cord replacements