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BME 312 Exam 3 > Types of Hydrogels > Flashcards

Types of Hydrogels Flashcards

1
Q

How is alginate made?

A
  1. naturally occurring brown seaweed is extracted from brown algae.
  2. extract is filtered
  3. sodium or calcium chloride is added to filtrate to precipitate alginate
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2
Q

How is alginic acid made?

A

alginate salt treated with dilute HCl

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3
Q

How is sodium alginate powder produced?

A

after further purification and conversion

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4
Q

Is alginate low or high cost to produce?

A

low cost

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5
Q

Describe alginate’s structure

A

linear copolymers containing blocks of M and G residues

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6
Q

What is the unique trait of G-blocks in alginates?

A

participate in intermolecular cross-linking with divalent cations (Ca^2+) to form hydrogels.

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7
Q

What 4 factors affect the physical properties of alginate and resultant hydrogel?

A
  1. composition (M/G ratio)
  2. sequence
  3. G-block length
  4. molecular weight
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8
Q

How are the mechanical properties of alginate gels enhanced?

A

by increasing the length of G-block and molecular weight

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9
Q

What are the properties of alginate?

A
  1. biocompatible
  2. low toxicity
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10
Q

What are the medical applications of alginate?

A
  1. wound healing
  2. delivery of bioactive agents
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11
Q

What are the pharmaceutical applications of alginate?

A
  1. thickening, gel-forming, and stabilizing agents
  2. delivery of low MW drugs
  3. drug release overtime in alginate gels
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12
Q

The physiochemical properties of alginate are highly dependent on what 4 things?

A
  1. molecular weight
  2. chemical composition
  3. cross-linking type
  4. cross-linking density
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13
Q

What types of cross-linking affect the properties of alginate?

A
  1. ionic
  2. covalent
  3. cell
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14
Q

What is debated about alginate?

A

biocompatibility

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15
Q

What is the structure of hyaluronic acid (HA)?

A

long unbranched polysaccharide chain, composed of twin sugar units

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16
Q

Where is hyaluronic acid found?

A
  1. extracellular matrix of skin, cartilage, vitreous humor, and other body tissue
  2. umbilical cord
  3. rooster combs
17
Q

What was the first medical use for hyaluronic acid in late 1950s?

A

vitreous substitution/replacement during eye surgery

18
Q

Hyaluronic acid is a ____________ naturally occurring in all organisms

A

carbohydrate

19
Q

When hyaluronic acid binds to water it gives it a more ___________ consistency similar to jello

A

viscous

20
Q

What are the 4 biological functions of HA?

A
  1. join synovial fluid
  2. vitreous fluid
  3. control of tissue hydration
  4. water transport
21
Q

What is HA’s function in the body?

A

to bind water and to lubricate moveable parts of the body such as joints and muscles

22
Q

What are the properties of hyaluronic acid?

A
  1. high density of negative charges
  2. hygroscopic
  3. high viscosity
  4. high capacity for lubrication, water absorption and retention
23
Q

What does the high capacity of lubrication, water absorption/retention allow for in hyaluronic acids?

A

allows the migration, adhesion and proliferation of cells to function

24
Q

In the body hyaluronic acid occurs in the ________ form, called ____________.

A

salt
hyaluronate

25
Q

List the 5 medical applications of HA

A
  1. ophthalmic
  2. reduces nerve impulses and sensitivity associated with pain
  3. enhances chondrocyte HA and proteoglycan synthesis
  4. reduces production of pro-inflammatory mediators and matrix metalloproteinases
  5. alters the behavior of immune cells
  6. orthopedic
26
Q

Describe the 3 orthopedic applications of HA

A
  1. development of cartilage
  2. maintenance of synovial fluid
  3. regeneration of tendons
27
Q

What 2 characteristics of HA make it optimal for orthopedics?

A
  1. viscoelastic nature
  2. ability to form highly hydrated matrices
28
Q

In the joint, HA acts as the _______ and the __________.

A

lubricant and shock absorber

29
Q

What is HA particularly useful for in ophthalmic applications?

A

space-filling matrix in the eye so intraocular injection of HA is used to maintain shape of anterior chamber

30
Q

HA solutions serve as ___________ of eye drops and as a __________ to eye tissue repair

A

viscosity-enhancing component and adjuvant

31
Q

Both HA and enzyme that eliminates HA, hyaluronidases, correlate with _______ progression

A

cancer

32
Q

Expression of HA synthases increases HA levels which leads to acceleration of __________ growth and _________.

A

tumor growth and metastasis

BME 312 Exam 3 (6 decks)

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