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Biomaterials > Test 2 > Flashcards

Test 2 Flashcards

0
Q

What are the factors that accelerate polymer degradation?

A

* more hydrophilic backbone * more reactive hydrolytic groups in the backbone * less crystallinity * more porosity *smaller device size

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1
Q

What are the advantages of synthetic biodegradable polymers over that of natural ones?

A

*tailor-able properties *predictable lot to lot uniformity * free from concerns of immunogenicity * reliable source of raw materials

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2
Q

What are the four steps of polymer degradation?

A

*water sorption * reduction of mechanical properties * reduction of molar mass * weight loss

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3
Q

Name two effects of bioerosion on polymer properties

A

Bulk erosion Surface erosion

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4
Q

Describe the two types of bioerosion

A

Bulk erosion: water enters polymer causes hydrolytic degradation. Component hollowed out. Finally crumbles. Releases acid groups Surface erosion: water penetration limited, degradation occurs on surface thinning of component over time integrity is maintained over longer time when compared to bulk erosion.

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5
Q

Give two examples of natural polymers and two examples of synthetic polymers

A

Natural polymers: * collagen * gelatin Synthetic polymers: *poly(dioxanone) *poly(anhydrides)

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6
Q

True/false All polymers are biodegradable

A

False

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7
Q

State 3 applications of biodegradable polymers

A

Wound management Orthopedic devices Tissue engineering

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8
Q

Describe the polymers degradation mechanism

A

enzymatic degradation

hydrolysis

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9
Q

What is the difference between surface errosion and bulk errosion?

A

In surface errosion the sample is eroded from the surface and in bulk errosion degradation occurs throughout the whole of the sample

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10
Q

True/ False

All biodegradable polymers are ideally biocompatible?

A

true

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11
Q

Name 3 factors that determine the rate of bioerrosion

A
  • chemical stability of polymer backbone
  • hydrophobicity of the monomer
  • morphology of polymer
  • fabrication process
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12
Q

2 benefits of having biodegradable polymer in the body

A
  • does not require a second surgery
  • avoid stress shielding
  • Offer tremendous potential as the basis for controlled
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13
Q

Which of the following is a biodegradable polymer?

A. polyethylene

B. polyvinyl chloride

C. nylon

D. polydioxanone

E. Dacron

A

D. polydioxanone

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14
Q

Name the system A and B

A

A- bulk eroding system

B-surface eroding system

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15
Q

which is not a synthetic polymer

A. PGA

B. polydioxanone

C. collagen

D. poly (lactic acid)

A

C. Collagen

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16
Q

x can be

A

O, N, S

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17
Q

State 2 advantages of using a natural polymer versus a synthetic polymer for biodegradable polymer applications

A
  • non toxic and low inflamatory reaction
  • degradation byproducts disposed metabolically
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18
Q

give example of 2 natural polymers for biomedical applications

A
  • proteins
  • polysaccharides
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19
Q

____________ is an example of a protein based natural polymer

A
  • collagen
  • fibrin
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20
Q

what is a GAG as it relates to the definition of a natural polymer

A

GAGs are the most abundant polysaccharides in the body

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21
Q

name 2 characteristics of elastin

A

highly amorphous

– exhibits ideal rubber elasticity

– insoluble elastin can be degraded by the enzyme elastase

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22
Q

______, ___________ and ________ amino acids are major componets of collagen type I protien

A

-Glycine (33%)
– Proline (25%)
– Hydroxyproline (25%)

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23
Q

state 2 biomedical applications of heparin

A
  • prevention and treatment of deep vein thrombosis (DVT)
  • adjunctive therapy in the treatment of arterial thrombosis
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24
Q

____ are the most abundant polysaccharides in the human body

A

GAGs

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25
Q

what is a glycoprotein

A

** glycoprotein:** proteins containing one or more covalently linked carbohydrate residues

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26
Q

describe the four levels of structual organization of collagen

A
  1. primary- sequence of amino acids
  2. **secondary- **local configuration polypetide chains that result from statisfaction of stereochemical angles and hydrogen bonding between peptide residues
  3. **tertiary- **global configurations of polypetide chains.. triple helical collagen molecule
  4. quarternary- comprising of several molecules packed into a specific lattice. basic unit of microfibril
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27
Q

give an example of physical modification of collagen

A

introducing porosity

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28
Q

give an example of a chemical modification

A

chemical cross linking

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29
Q

what is a monosaccharide

A

– monosaccharide: Simple sugar; carbohydrate which cannot be decomposed by hydrolysis.

30
Q

list 3 disadvantages of using natural polymers versus synthetic polymers

A
  • –immunogenicity
  • temperature sensitivity
  • Lot to lot variability
31
Q

what are collagenases

A

collagenases are naturally present in healing wounds

32
Q

natural materials have the ability to be degraded by natural ___, and are ideal for ____ term applications

A

enzymes

short

33
Q

what is the source for obtaining natural polymers

A

plants, animals, microorganisms

34
Q

2 representative sources of natural biodegradable polymers are from ____ and _________

A

polysaccharides

proteins

35
Q

name 2 protein based natural biodegradable polymer

A

amino acids

collagen

36
Q

name 2 polysaccharide based natural biodegradable polymers

A

cellulose

startch

37
Q

give an example of chemical modification of collagen to control its biodegradation

A

chemical cross linking between chains

38
Q

what is a proteoglycan

A

proteoglycan: glycoprotein with a very high carbohydrate content

39
Q

Hydrogels are polymeric structures held together as water swollen gels by ______ and ________

A

primary covalent links

ionic forces

40
Q

name 2 distinguishing features of hydrogels

A

water insoluble

polymers capable of swelling substantially in aqueus solution

41
Q

name 3 examples of biological hydrogels

A

jello

blood clot

DNA/RNA

42
Q
A
43
Q

state 2 applications of hydrogels

A

pharmaceutical

contact lenses

44
Q

define hydrogels

A

Hydrogels are polymeric structures held together as water swollen gels by
– Primary covalent links
– Ionic forces
– Hydrogen bonds
– Hydrophobic interactions
– Polymer crystallites
– Physical entanglements
– Combination of two or more interactions

45
Q

classify hydrogels by ionic charges

A
  • neutral hydrogels
  • anionic hydrogels
  • cationic hydrogels
  • ampholytic hydrogels
46
Q

describe classification of hydrogels based on structure

A
  • amorphous hydrogels ( chains randomly arranged)
  • semicrystalline hydrogels (dense regions of ordered macromolecules
  • hydrogen bonded hydrogels
47
Q

state the different ways to cross link formation in hydrogels

A

radiation or chemical reaction

48
Q

define superabsorbant hydrogels

A

when content of water exceeds 95% of total weight

49
Q

eleborate on how degree of swelling of hydrogels could be quantified by

A
  • ratio of sample volume in the swollen state to volume in the dry state
    – weight degree of swelling: ratio of the weight of swollen sample to that of the dry sample
50
Q

name 3 reactions that could induce cross links to form hydrogels

A

electron beams

gamma rays

UV light

51
Q

why is degree of swelling important in a hydrogel

A

Why is the degree of swelling important?
– solute diffusion coefficient through the hydrogel
– surface properties and surface mobility
– optical properties (particularly for contact lens applications)
–mechanical properties

52
Q

which one of the following is a natural hydrogel forming polymer

A. polyethelene glycol

B.. polylactic acid

C. polysodium alginate

D. polyn-isopropyl acrylamide

A

A polyethelene glycol

53
Q

what percent of water must be in a hydrogel for it to be considered as a super absorbant hydrogel

A

95%

54
Q

how would a drug be delivered using a hyrdorgel

A

drug gets trapped in the hydrogel during polymerization
– drug introduced during swelling in water

55
Q

state 2 defects in crosslinked structures of hydrogels

A

unreacted functionality

chain loops

56
Q

state 2 biomedical applications for ceramics

A

dental implants

femoral head

57
Q

what are the 2 most commonly used structural bioceramics

A

alumina and zirconia

58
Q

what are the advantages and disadvantages of ceramics for biomedical applications

A

Advantages

  • inert in body
  • high wear resistance
  • high modulus and compressive strength

Disadvantages

  • brittle
  • low tensile strength
  • poor fatigue resistance
59
Q

define bioactivity as it relates to ceramics

A

property that allows the material to directly bond with the new forming bone

60
Q

what is true about bioactive ceramics

A. compostions are: SiO2, CaO, NaO

B. can be used as bone cement and filler and coating

C. can not be used for load bearing applications

D. all true

A

D all true

61
Q

what is NOT one of the four bone mimicry properties of calcium phosphate

A. interconnecting porosity

B. biodegradability

C. osteoconductivity

D. Ductility

E. bioactivity

A

D ductility

62
Q

what is the most stable form of Calcium phosphate

A

crystalline hydroxyapatite

63
Q

name 3 uses of biodegrable ceramic-calcium phosphate

A

bone replacement

coating of metal implants

drug delivery systems

64
Q

calcium ____ are the most common biodegrable ceramics

A

calcium phosphate

65
Q

______ and _______ are the most common structural ceramics

A

zirconia and alumina

66
Q

list 4 physical properties of ceramics

A
  • Highly inert; thus, biocompatible
    . • Hard and brittle
    • Wear resistant
    • Good aesthetic appearance
67
Q

list 3 examples of ceramics used for biomedical applications

A
  • alumina
  • zirconia
  • calcium phosphate
68
Q

elaborate on a method for processing of ceramics

A

forming: the clay or slurry is made into parts by pressing into mold

69
Q

describe the classification of ceramics based on its chemical reactivity in the body environment

A

Nearly inert ceramics e.g., alumina and carbons show little chemical reactivity even after thousands of hours or exposure to the physiological pH and therefore show minimal interfacial bonds with living tissues.
 Surface reactive bioglass ceramics exhibit an intermediate behavior. In these ceramics, surface provides bonding sites for the constituents of soft tissues and cell membranes, producing tissue adherence.
• Completely Resorbable

70
Q

name an inert ceramic and state one of its biomedical application

A

alumina

knee prosthesis

71
Q

state 2 dental applications of ceramics

A

dental restorations

crowns and bridges

72
Q

give an example of carbon based biomaterial and state its biomedical application

A

pyrolytic carbon

Compatibility of pyrolitic carbon coated devices with blood have resulted in extensive use in heart valves

73
Q

what is pyrolytic carbon

A

Pyrolytic carbon is a material similar to graphite, but with some covalent bonding between its graphene sheets

man made

Biomaterials (4 decks)

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