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21 Cards in this Set
- Front
- Back
Molecules to deliver
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***Growth factors
* steroids * anti-inflammatories/immuno-supressants |
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TYPES OF RELEASE
bolus |
one single delivery (ex: injection)
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TYPES OF RELEASE
sustained |
delivery is prolonged
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TYPES OF RELEASE
controlled |
predictability and reproducibility of dose delivery
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DELIVERY MECHANISMS
systemic |
addition of a bolus; uncontrolled; requires a lot of the growth factor
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DELIVERY MECHANISMS
soluble delivery |
growth factor is adsorbed or entrapped in the scaffold
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DELIVERY MECHANISMS
tethered |
- can be covalent or non-covalent bonds
- release can be mediated by cellular activity - we have more control over time of delivery |
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TYPES OF SOLUBLE DELIVERY
dissolution |
- growth factor is directly soluble in the polymer
- completely homogeneous |
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TYPES OF SOLUBLE DELIVERY
adsorption |
- only if the scaffold supports protein adsorption
- commonly used with PLGA |
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TYPES OF SOLUBLE DELIVERY
emulsions |
- growth factors are phase-separated from the rest of the polymer
- allows tailoring of release from the pocket |
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TYPES OF SOLUBLE DELIVERY
suspension |
- growth factors are not soluble in the polymer
- not released until the polymer degrades |
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how to make an interspersed loading homogeneous
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** dissolution **
1) mix growth factor in polymer solution 2) cross-link the material |
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how to make an interspersed loading heterogeneous
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- adsorb onto surface
OR - emulsion |
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INTERSPERSED DELIVERY MECHANISMS
solely diffusion |
- controlled by diffusion coefficient
- use if growth factors can fit through scaffold pores |
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INTERSPERSED DELIVERY MECHANISMS
diffusion and bulk degradation |
- growth factor diffuses as polymer degrades
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INTERSPERSED DELIVERY MECHANISMS
surface erosion |
- growth factor released with surface hydrolysis
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altering material release profiles
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- porosity
- degradation |
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altering growth factor release profiles
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- all growth factor properties
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growth factors can be affected by:
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- chemicals
- pH changes - adsorption |
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how to alter delivery of covalently tethered growth factors
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degrade the cross-linker, either hydrolytically or enzymatically
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how to alter delivery of heparin-bound growth factors
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alter the ratio of heparin to growth factor; more heparin = slower release
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