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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
\_\_\_\_ are the most abundant polysaccharides in the human body
GAGs
25
what is a glycoprotein
** glycoprotein:** proteins containing one or more covalently linked carbohydrate residues
26
describe the four levels of structual organization of collagen
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
27
give an example of physical modification of collagen
introducing porosity
28
give an example of a chemical modification
chemical cross linking
29
what is a monosaccharide
– monosaccharide: Simple sugar; carbohydrate which cannot be decomposed by hydrolysis.
30
list 3 disadvantages of using natural polymers versus synthetic polymers
* –immunogenicity * temperature sensitivity * Lot to lot variability
31
what are collagenases
collagenases are naturally present in healing wounds
32
natural materials have the ability to be degraded by natural \_\_\_, and are ideal for ____ term applications
enzymes short
33
what is the source for obtaining natural polymers
plants, animals, microorganisms
34
2 representative sources of natural biodegradable polymers are from ____ and \_\_\_\_\_\_\_\_\_
polysaccharides proteins
35
name 2 protein based natural biodegradable polymer
amino acids collagen
36
name 2 polysaccharide based natural biodegradable polymers
cellulose startch
37
give an example of chemical modification of collagen to control its biodegradation
chemical cross linking between chains
38
what is a proteoglycan
proteoglycan: glycoprotein with a very high carbohydrate content
39
Hydrogels are polymeric structures held together as water swollen gels by ______ and \_\_\_\_\_\_\_\_
primary covalent links ionic forces
40
name 2 distinguishing features of hydrogels
water insoluble polymers capable of swelling substantially in aqueus solution
41
name 3 examples of biological hydrogels
jello blood clot DNA/RNA
42
43
state 2 applications of hydrogels
pharmaceutical contact lenses
44
define hydrogels
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
classify hydrogels by ionic charges
* neutral hydrogels * anionic hydrogels * cationic hydrogels * ampholytic hydrogels
46
describe classification of hydrogels based on structure
* amorphous hydrogels ( chains randomly arranged) * semicrystalline hydrogels (dense regions of ordered macromolecules * hydrogen bonded hydrogels
47
state the different ways to cross link formation in hydrogels
radiation or chemical reaction
48
define superabsorbant hydrogels
when content of water exceeds 95% of total weight
49
eleborate on how degree of swelling of hydrogels could be quantified by
- 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
name 3 reactions that could induce cross links to form hydrogels
electron beams gamma rays UV light
51
why is degree of swelling important in a hydrogel
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
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 polyethelene glycol
53
what percent of water must be in a hydrogel for it to be considered as a super absorbant hydrogel
95%
54
how would a drug be delivered using a hyrdorgel
drug gets trapped in the hydrogel during polymerization – drug introduced during swelling in water
55
state 2 defects in crosslinked structures of hydrogels
unreacted functionality chain loops
56
state 2 biomedical applications for ceramics
dental implants femoral head
57
what are the 2 most commonly used structural bioceramics
alumina and zirconia
58
what are the advantages and disadvantages of ceramics for biomedical applications
**_Advantages_** * inert in body * high wear resistance * high modulus and compressive strength **_Disadvantages_** * brittle * low tensile strength * poor fatigue resistance
59
define bioactivity as it relates to ceramics
property that allows the material to directly bond with the new forming bone
60
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
D all true
61
what is NOT one of the four bone mimicry properties of calcium phosphate A. interconnecting porosity B. biodegradability C. osteoconductivity D. Ductility E. bioactivity
D ductility
62
what is the most stable form of Calcium phosphate
crystalline hydroxyapatite
63
name 3 uses of biodegrable ceramic-calcium phosphate
bone replacement coating of metal implants drug delivery systems
64
calcium ____ are the most common biodegrable ceramics
calcium phosphate
65
\_\_\_\_\_\_ and _______ are the most common structural ceramics
zirconia and alumina
66
list 4 physical properties of ceramics
* Highly inert; thus, biocompatible . • Hard and brittle • Wear resistant • Good aesthetic appearance
67
list 3 examples of ceramics used for biomedical applications
* alumina * zirconia * calcium phosphate
68
elaborate on a method for processing of ceramics
forming: the clay or slurry is made into parts by pressing into mold
69
describe the classification of ceramics based on its chemical reactivity in the body environment
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
name an inert ceramic and state one of its biomedical application
alumina knee prosthesis
71
state 2 dental applications of ceramics
dental restorations crowns and bridges
72
give an example of carbon based biomaterial and state its biomedical application
pyrolytic carbon Compatibility of pyrolitic carbon coated devices with blood have resulted in extensive use in heart valves
73
what is pyrolytic carbon
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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