Biodegradable Polymers Flashcards
Why would a medical practitioner like a material to degrade in the body?
- do not require a second surgery for removal
- avoid stress shielding (metal disadvantage)
- tremendous potential as the basis for controlled drug delivery
Degradation
bond cleavage event leading to a change in the structure of a material, characterized by a loss of properties and/or fragmentation.
Bond cleavage can occur through
hydrolysis, enzymatic activity, or exposure to light
Resorable
process of eliminating the degradation products
Erosion
process that results in the mas s loss of a material that may result in a change of size, shape, or mass
Biodegradation
cleavage of bonds as a consequence of a biological agent, such as an enzyme, cell, or microorganism
Surface erosion
erosion that is restricted to the surface of a material and proceeds via an erosion front, degradation is almost linear to time, gradually degrades
Bulk erosion
erosion that occurs throughout a sample causing the whole material to degrade, entire mass loss, abrupt change in the structure
Surface erosion applications
Drug delivery
- drug release rate is independent of diffusion
- easily altered by changing the device geometry
Why do we prefer synthetic polymers?
- tailor-able properties
- can design different monomers
- predictable lot-to-lot uniformity
- consistent properties between batches as opposed to natural polymers
- free from concerns of immunogenicity
- select the monomers and choose ones that aren’t immunogenic
- reliable source of raw materials
Poly(lactic-co-glycolic) acid (PLGA)
Degradable polymer
- two monomers to create, glycolide and lactide
- polymer with high physiological context
- biocompatibility
- flexibility to modulate the ratio and therefore the degradation rate
- change ratio of lactic and glycolic acid can modulate degradation and mechanical strength
- different modifications to have better interactions with biological environment
