Week 11 Flashcards

1
Q

materials found in biological systems (e.g., nature) that could be used in biomedical applications

A

natural biomaterials

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2
Q

What are two examples of natural biomaterials?

A
  1. jade stones –> replace tooth
  2. coral –> bone graft
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3
Q

What are the 4 advantages of natural biomaterials?

A
  1. cell attachment
  2. enhance mechanical properties of synthetic biomaterials
  3. bind and deliver macromolecules
  4. improved biocompatibility
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4
Q

What are 3 disadvantages of natural biomaterials?

A
  1. increased immunogenic
  2. structural complexity
  3. degraded by enzymes
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5
Q

What are 3 applications of natural biomaterials?

A
  1. tissue engineering
  2. regenerative medicine
    - wound healing
    - antibacterial coatings
  3. medical devices
    - bioprosthetic implants
    - heart valves
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6
Q

Natural biomaterials can mimic the properties of what two materials?

A
  1. polymers
  2. ceramics
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7
Q

What are 5 examples of protein-based natural biomaterials?

A
  1. collagen
  2. gelatin
  3. silk fibroin
  4. fibrin
  5. elastin
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8
Q

What are 7 examples of polysaccharide-based natural biomaterials?

A
  1. chitosan
  2. starch
  3. alginate
  4. hyaluronan
  5. chondroitin
  6. sulfate
  7. dextran
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9
Q

This type of natural biomaterial is a protein that is exclusively found in animals and is the most abundant protein in the human body

A

collagen

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10
Q

What is collagen a part of?

A

extracellular matrix

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11
Q

What is the main function of collagen?

A

provide structural support for connective tissues

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12
Q

What are the two primary features of collagen?

A
  1. act as glue connecting tissues
  2. strength and structural integrity
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13
Q

What is the primary protein of the skin?

A

collagen

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14
Q

Collagen is a type of connective tissue found in what 4 parts of the body?

A
  1. bone
  2. dentin
  3. tendon
  4. ligaments
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15
Q

Collagen makes up ___% of muscle tissue

A

1-2%

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16
Q

How many different types of collagen have been identified?

A

28

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17
Q

Each different molecular type of collagen is unique in what 4 ways?

A
  1. composition
  2. structure
  3. function
  4. tissue specificity
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18
Q

What are the two major types of collagen which make up 90% of the collagen in the body?

A
  1. Type I
  2. Type V
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19
Q

What type of collagen is found in dentin?

A

Type I

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20
Q

Describe the hierarchy of collagen

A

amino acids –> expand and grow and form helices –> tropocollagen –> crosslinking –> fibrils –> multiply fibrils –> fibers

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21
Q

What is the primary function of cross-linking?

A

side-by-side packing of fibrils to increase strength

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22
Q

What happens if cross-linking is inhibited?

A

tensile strength is drastically reduced

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23
Q

What happens to the amount of cross-linking as you age?

A

it increases

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24
Q

Describe the mechanical response of collagen

A

this is what the trend will look like if you apply a stress to break the collagen fiber

“toe region” –> tangled and you begin to stretch it

“linear region” –> collagen fibers are all in a line with eachother

“failure” –> collapse

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25
Q

What is the most abundant type of collagen in the human body?

A

type I

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26
Q

What type of collagen is the predominant form used in biomaterials application?

A

type I

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27
Q

Where are 8 places type I collagen is found?

A
  1. skin
  2. dentin
  3. cornea
  4. blood vessels
  5. bone
  6. tendon
  7. ligament
  8. fibrocartilage
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28
Q

What does type I collagen aggregate into?

A

fibrils

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29
Q

What does the diameter of type I collagen depend on?

A
  1. age
  2. tissue

(50 nm - 500 nm)

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30
Q

Describe type I collagen in teeth

A
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31
Q

forms a dense network array of individual thin fibrils, with an interfibrillar matrix

A

type II collagen

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32
Q

Where is type 2 collagen found?

A

articular cartilage

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33
Q

What 4 things is type II collagen made of?

A
  1. proteoglycans
  2. glycoprteins
  3. non-collagenous proteins
  4. water
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34
Q

What two things does the fibrillar network of type II allow?

A
  1. cartilage to entrap proteoglycan aggregate
  2. provide tensile strength to tissue
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35
Q

Another name for type II collagen

A

cartilage

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36
Q

This type of collagen is composed of 3 identical peptide a-chains (homotrimer)

A

type III collagen

37
Q

What does type III collagen resemble?

A

other fibrillar collagens in structure and function

38
Q

Describe the proteins in type III collagen

A

long, inflexible, triple-helical domain

39
Q

Type III collagen accounts for ___ of collagen in adult skin

A

20%

40
Q

Where is type III collagen found?

A
  1. skin of newborns
  2. blood vessels
  3. ligaments and internal organs
41
Q

Where is type IV collagen found?

A
  1. eye lens
  2. blood vessels
  3. kidneys
  4. basal lamina
42
Q

Describe the overall arrangement of type IV collagen

A

sloppy with kinks

43
Q

True or false: Type IV collagen does not form fibril or fibers

A

True

44
Q

What does Type IV collagen form?

A

meshes or networks which filter cells, molecules and light

45
Q

Compare the 4 types of collagen

A
46
Q

Where is collagen isolated from?

A
  1. animals
    - bovine
    - equine
    - porcine
  2. human
    - cadaver
    - placentas
47
Q

Collagen is found in combination with what 3 things?

A
  1. growth factors
  2. silicones
  3. fibroblasts
48
Q

What 3 forms are collagen found as?

A
  1. meshes
  2. gels
  3. mats
49
Q

Collagen is ideally found without tissues or cells, also known as

A

contamination

50
Q

What are collagen scaffolds used for?

A

bone regeneration and tissue enginering

51
Q

What are collagen scaffolds often mixed with to improve performance?

A

hydroxyapetite

52
Q

Describe 4 biomedical applications of collagen

A
53
Q

This is a type of connective tissue protein with rubber-like properties

A

elastin

54
Q

Natural elastin is (soluble/insoluble) extracellular matrix

A

insoluble

55
Q

Where is elastin found (5 places)?

A
  1. skin
  2. bladder
  3. lungs
  4. arteries
  5. invertebral discs
56
Q

What 3 things are of major importance in elastin?

A
  1. elasticity
  2. flexibility
  3. strength
57
Q

The structure of elastin is primarily compose of

A

small non-polar amino acid residues
- glycine, valine, alanine, proline

58
Q

In elastin, the interchain crosslinks form

A

desmosine residues

59
Q

What kind of coil confirmation does elastin posess?

A

irregular

60
Q

Elastin fibers consist of an albuminoid protein called

A

elastin

61
Q

What are two properties of elastin fibers?

A
  1. pliable
  2. elastic
62
Q

Elastin fibers can be stretched to ___% of their original length without breaking and then return to its original state

A

150%

63
Q

Compare collagen and elastin

A

collagen dominated tissue will behave more like a ceramic (more stiff)

elastin dominated is more soft and will get really elongated

64
Q

What are the 3 properties of elastin?

A
  1. insoluble due to crosslinks
  2. hydrophobic due to amino acids (75%)
  3. resistant to enzymatic, chemical, and physical degredation
65
Q

Cross-links in elastin can be modified to do what 3 things?

A
  1. prevent mineralization
  2. promote cell adhesion and growth
  3. control degradation rate
66
Q

How much elastin is in the lung?

A

30%

67
Q

How much elastin is in the skin?

A

3%

68
Q

How much elastin is in ligaments and arteries?

A

50-70%

69
Q

Flexibility allows the organs to undergo what 3 things?

A
  1. strain and deformation without rupture
  2. store energy from deformation
  3. recover when stress is removed
70
Q

What are the biomedical applications of elastin?

A
71
Q

What are the monomers of chitosan?

A

monosaccharides

72
Q

What is chitosan derived from?

A

chitin

73
Q

Where is chitin found?

A
  1. cell walls of fungi
  2. cuticles of insects
  3. exoskeletons of shellfish
74
Q

This is made up of a long linear polymeric chain of N-acetyl-d-glucosamine

A

chitin

75
Q

How is chitosan formed from chitin?

A

deacetylation (remove acetyl group)

76
Q

removal of acetyl functional group from chitin with hydroxides and high temperature

A

deacetylation

77
Q

What 3 things does the removal of the acetyl from the glucosamine allow?

A
  1. tighter packing
  2. increase crystallinity
  3. solubility (DDA>50%)
78
Q

What are the 4 favourable properties of chitosan?

A
  1. minimal foreign body reaction
  2. dissolves in water
  3. available side groups can attach to molecules (i.e., growth factors)
  4. mechanical and biodegredation controllable through polymer length, porposity, and DDA
79
Q

What are the 5 features of chitosan?

A
80
Q

What is commercial chitosan used for?

A
  1. repair focal cartilage lesions
  2. wound dressing for blood loss
81
Q

a family of non-branched anionic polysaccharide copolymers that are derived from psuedomonas and axotobacter bacteria

A

alginate

82
Q

True or false: alginate can be found in marine algae such as brown seaweed

A

true

83
Q

What are two other names for alginate?

A
  1. alginic acid
  2. algin
84
Q

What are the 2 alginate monomers?

A
85
Q

What are the favourable properties of alginate?

A
86
Q

In alginates, which residues can undergo acetylation? Which can’t?

A

acetylation - mannuronic acid residues
no acetylation - guluronic residues

87
Q

What is the range of solutions for alginates?

A

slimy and viscous

88
Q

Describe alginate impression material

A