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BME 312 Exam 3 > Natural Polymers, Polysaccharide, & intro to Hydrogels > Flashcards

Natural Polymers, Polysaccharide, & intro to Hydrogels Flashcards

1
Q

What are the 4 characteristics of natural polymers?

A
  1. environmentally friendly
  2. emit low greenhouse gas
  3. low cytotoxicity
  4. biocompatible
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2
Q

What are the 6 sources for natural polymers?

A
  1. plants
  2. crustaceans
  3. animals
  4. humans
  5. microbials
  6. fungi
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3
Q

Where do polysaccharides mainly come from?

A

plants

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4
Q

What are polysaccharides?

A

long polymer chains composed of monosaccharide units bound together by glycosidic linkages

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5
Q

What is glucose and where does it come from?

A

simple sugar and comes from plants and algae

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6
Q

What is starch composed of?

A

30% amylose-linear and 70% amylopectin-branched

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7
Q

What are the 2 properties of starch?

A
  1. insoluble in COLD water
  2. hygroscopic - absorbs moisture from air
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8
Q

hygroscopic

A

absorbs moisture from air

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9
Q

What are the 4 applications with starch?

A
  1. bone replacement implants
  2. bone cements
  3. drug delivery
  4. tissue scaffolds
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10
Q

What sea animals results in abundant crustacean waste materials?

A
  1. lobsters
  2. crabs
  3. shrimps
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11
Q

What does chitin come from?

A

the processed shells and heads of crustaceans

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12
Q

What is chitin?

A

most important component of crustacean and insect exoskeletons or the cell walls of some bacteria and fungi (ex. mushrooms).
1. exoskeletons of crustacean and insects
2. cell walls of some bacteria and fungi

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13
Q

Chitin is a __________________ structure

A

highly crystalline structure

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14
Q

What are the 3 properties of the chitin structure?

A
  1. strong
  2. rigid
  3. linear
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15
Q

Chitin is soluble in concentrated ________________

A

acidic solvents
ex.
1. H3PO4
2. HCl
3. H2SO4
4. amide/LiCl

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16
Q

Chitin has trouble dissolving in common _____________

A

common organic solvents
ex.
1. DMSO
2. DMF
3. DCM
4. NMP

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17
Q

What is the disadvantage of chitin being insoluble in common solvents?

A

causes difficulty with processing

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18
Q

Chitosan is derived from?

A

Chitin

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19
Q

What groups in chitosan chains facilitate chemical modification?

A

amino and hydroxyl groups

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20
Q

What two things are known to affect the properties of derived materials?

A
  1. degree of deacetylation
  2. molecular weight
21
Q

What are the 10 properties of chitosan?

A
  1. antioxidant
  2. hemostatic
  3. immunity enhancing
  4. anti-microbial
  5. analgesic
  6. biocompatible
  7. biodegradable
  8. almost water-soluble
  9. anti-tumor
  10. chelating
22
Q

What medical issues does chitosan help reduce the time for?

A
  1. time of wound healing
  2. rebuilding connective tissue
23
Q

Describe the anti-microbial activity of chitosan

A
  1. inhibits mRNA and protein synthesis via penetration of chitosan into the nuclei of the microorganism
  2. formation of an exterior barrier which deprives bacteria from nutrients and growth
  3. cationic charge interferes with negatively charged bacteria
24
Q

What two types of chitosan might be useful in tumor growth prevention?

A
  1. low-molecular weight, water-soluble chitosans
  2. oligochitosans
25
How does chitosan prevent tumor growth?
partly through enhancing cytotoxic activity against tumors as an immunomodulator
26
chelation
ability to absorb metal ions
27
what natural polymer has the highest chelation rate?
chitosan
28
What applications is chitosan's high chelation rate used for?
1. water filtration 2. removal of dyes, etc.
29
What can be enhanced for the chelation effects of chitosan?
1. absorption 2. selectivity
30
Modifications in what groups cause chemical and physical changes for chitosan?
amine and hydroxyl groups
31
What metals can chitosan absorb?
Zn, Hg, and Ag where Ag is a disinfectant or bactericide
32
Changing what effects absorption for chelation rate of chitosan?
pH
33
What two things have the properties of disinfectants and bactericides?
chitosan and metal ions (Zn, Zr, and Ag)
34
What are the non-medical uses for chitosan?
1. cosmetic moisturizers 2. coating for fruits and vegetables 3. water treatments (filters)
35
Pullulan is a _______ _______ polysaccharide of ____________
linear homopolysaccharide of glucose
36
Where does pullulan mainly come from?
strains of fungus Aureobasidium pullulans
37
Production process for pullulan is complicated because _________________________.
removal of melanin from Aureobasidium which adds to the production cost.
38
Pullulan has a very high __________
molecular weight
39
The flexibility of pullulan allows for it to form ________and ________.
fibers and distinct films.
40
List the 8 properties of pullulan
1. very flexible 2. hydrophilic - dissolves in water 3. non-hydroscopic 4. adhesive 5. oxygen impermeability 6. odorless, tasteless, and edible 7. transparent 8. low viscosity
41
What does low viscosity for pullulan mean?
it is stable when exposed to heating at high temperatures and changes in pH
42
4 Methods to alter properties of pullulan and results:
1. esterification or etherification - to reduce water solubility 2. hydrogenation - to increase stability 3. carboxylation - to increase solubility in cold water 4. co-polymerization - to change function and abilities
43
What are the medical applications of pullulan?
1. drug delivery - coating for sustained release 2. wound healing 3. vaccines 4. tissue engineering
44
What are the 2 limitations with pullulan?
1. mechanical properties are weak due to its hydrophilic nature 2. high cost of production limits its usage
45
What are hydrogels?
water-swollen, cross-linked polymer network produced by simple reaction of one or more monomers
46
What is the unique property of hydrogels with water?
swell and retain significant amount of water but does not dissolve in water
47
What causes the unique property of hydrogels with water?
hydrophilic functional groups attached to the polymer backbone
48
Why don't hydrogels dissolve in water?
their crosslinking does not allow them to dissolve
49
What does the structure of hydrogels mimic?
body tissue

BME 312 Exam 3 (6 decks)

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