chap4 cntbdv

Which is traditional scaffold fabricating methods?

1.   Solvent casting particulate leaching

2.   Gas foaming

3.   Phase separation

4.   Melt moulding

5.   Emulsion freeze-drying

6.   Solution casting

7.   Freeze-drying

8.   Stereolithography Apparatus (SLA) system

9.   Fused Deposition Modeling (FDM)

• 1,2,3

• 4, 5, 6

• 7, 8, 9

• 1, 2, 3, 4, 5, 6, 7

Arrange the following steps into a scaffolding process of phase separation?

1: Dissolving polymers in phenol or naphthalene

2: Add bioactive molecules (such as alkaline phosphatase)

3: Lower the temperature

4: Solvent sublimation

5: Scaffold foam with biological molecules that work inside the structure

6: Solvent evaporation

7: Dissolving PLA in methylene chloride one more time

• 1, 2, 3, 4, 5

• 7, 5, 4, 3, 1

• 2, 6, 3, 5, 4

• 2, 7, 5, 4, 3

Which is Solid freeform fabrication (SFF)?

1.   Three dimensional printing (3DP)

2.   Stereolithography Apparatus (SLA) system

3.   Fused Deposition Modeling (FDM)

4.   Plotter 3D system

5.   Phase change jet printing

6.   Melt moulding

7.   Emulsion freeze-drying

8.   Solution casting

• 1, 2, 3, 4, 5

• 1, 2, 4, 8

• 3, 5, 6, 7

• All above correct

What is the common materials for scaffolds?

1.    PPF (Poly(propylene fumarate))

2.    PGA (Poly(glycolic acid))

3.    PLA (poly(lactic acid))

4.    PLGA (poly(lactic acid-co-glycolic acid))

5.    PCL (poly(ε-caprolactone) )

6.    PHB (poly(hydroxy butyrate))

7.    PVC (Polyvinyl clorua)

8.    PE (polyetylen) 

9. 9.PS (polystyren) 

• 1, 2, 3, 4, 5, 6

• 2, 4, 5, 7, 8

• 2, 3, 4, 7

• 1, 7, 8, 9

In phase separation, we lower the temperature for what purpose?

• Create liquid-liquid phase separation and cool to make a two-phase solid

• Cool to make a two-phase solid and dry scaffold

• Soak gelatin in water to remove and dry scaffold

• Create liquid-liquid phase separation and Created scaffold has the shape of the mold

What is the limitations of tissue engineering scaffold by using gas foaming method?

• Only 10-30% of pores are interconnected. The mesh fibers have weak mechanical properties. Solvent backlog make high risk of toxins and cancer

• Can not ensure the interconnection of pores.

• Only thin scaffold layers can be created because it is difficult to remove salt particles inside the mold.

• Can not control exactly the size and shape of pores

Which scaffold parameters the solid freeform fabrication (SFF) method can controls ?

• Pore size, porous state, the distribution of pores, as well as how to organize the artificial vessel system

• Pore size, the spatial distribution of pores

• Porous state, pore size

• The mesh fibers have weak mechanical properties

What is the solid freeform fabrication (SFF) definition?

• is the production of freeform solid objects directly from a computer model without part-specific tooling or human intervention

• processes by which scaffolds with a continuous, uninterrupted pore structure can be made

• is the production directly from a computer by using CAD (computer aided design) make model and 3DP ( three domensional printing)

• All of above wrong

What is the step of solution casting?

1.   Dissolve PLGA in chloroform

2.   Add methanol (creating precipitate)

3.   Cold-dry bones can be combined with PLGA

4.   Composite material is pressed into the mold

5.   Heat up to 45-48^oC in 24 hours (creating scaffold)

6.   Dissolve polymer in cold acetic acid or benzene

7.   Created scaffold has the shape of the mold.

8.   Identify two non-mixed layers (water-oil emulsion)

• 1, 2, 3, 4, 5

• 6, 4, 3, 2, 5

• 1, 2, 3, 5, 8

• 1, 3, 7, 8, 4

What is the step of emulsion freeze-drying?

1.  Using PLGA powder and gelatin microspheres having special diameter to fill a Teflon mold

2.  Soak gelatin in water to remove

3.  Freeze-drying (creating porous mold)

4.  Add hyper-clean water to methylene chloride and PGA solution

5.  Identify two non-mixed layers (water-oil emulsion)

6.  Refrigerate in liquid nitrogen

7.  Freeze-drying (creating porous structure)

• 4, 5, 6, 7

• 1, 2, 3, 5

• 3, 2, 4, 1

• 1, 3, 4, 5