Biomaterials

Question 1

Biomaterials desirable properties? (10)

Answer 1

Biocompatible
Biodegradable
Mechanics
   - strength
   - toughness
   - flexibility
Sterilisable
Non-toxic
Surface area
Texture & Surface area
FBR

Question 2

Hydrogel advantages (4) & disadvantages (2)?

Answer 2

Ad:
Range of chemistries
Biocompatible
High water content
Potentially injectable
Dis:
Poor mechanical properties
Difficult to sterilise

Question 3

Hydrogel formation?

Answer 3

Physical

Chemical

Question 4

Alginate & Dextran

Answer 4

Polysaccharides

Injectable, in situ gelling materials

Question 5

Chitosan

Answer 5

Polysaccharide
Minimal FBR
Bone, cartilage, skin, liver

Question 6

Cellulose

Answer 6

Polysaccharide
High mechanical & chemical stability
BUT no in vivo biodegradation

Question 7

Starch

Answer 7

Polysaccharide

Partially degradable bone cements

Question 8

Hyuluronan

Answer 8

Polysaccharide
stimulates differentiation & proliferation of chondrocytes, bone marrow stromal cells
Soft tissue eng

Question 9

Collagen (ad/dis)

Answer 9

Protein
Wound dressing, artificial skin
AD: biocom/deg, cell binding, low antigenicity
DIS: low mech strength, risk of viral infection

Question 10

Elastin

Answer 10

Protein

Excellent properties but complex purification and difficult processing

Question 11

Polymer synthesis methods?

Answer 11

Addition
Step growth
Ring-opening

Question 12

Homo vs copolymer?

Answer 12

Homo: higher Tg, slower degradation
Co: lower Tg, faster degradation

Question 13

Biodegradable definition?

Answer 13

a substance capable of being decomposed by bacteria or other living organisms

Question 14

Erosion definition?

Answer 14

Loss of mass of materials when degradation products diffuse and dissolve

Question 15

Bulk erosion vs surface erosion

Answer 15

graphs

Question 16

Why is degradation faster in vivo?

Answer 16

Faster chain scission via FBR
Faster mass loss from passive & active transport, increased solubility of oligomers due to presence of lipids, mechanical stresses and cellular activity

Question 17

Ceramic definiton?

Answer 17

A body of crystalline, or partly crystalline, structure which is produced from essentially inorganic, nonmetallic substances and is formed from a molten mass which solidifies on cooling

Question 18

Glass definition?

Answer 18

Specific form of amorphous inorganic solids that results from very rapid cooling of a viscous molten material to a solid state without crystallising

Question 19

Glass-ceramic definition?

Answer 19

A slower and controlled cooling down of a glass, partly crystalline and partly glassy

Question 20

Ceramic microstructure features?

Answer 20

Porosity, grains (boundaries, size, shape, orientation), microcracks
Effect mechanical properties (Hall-Petch)

Question 21

Ceramic processing

Answer 21

Sintering
Hot pressing
Defects affect final properties!

Question 22

Ceramic porosity equation

Answer 22

-

Question 23

Ceramic degradation mechanisms?

Answer 23

Physiochemical, influenced by:
  - crystalline features (amorphous is faster)
  - thermodynamic stability
  - additives
Cell-mediated degradation, influenced by:
  - osteoclasts & macrophages
  - physiochemical kinetics
  - surface roughness (rough = faster)