Biomedical Engineering Reference
In-Depth Information
1
Polyesters
Adam L. Sisson , Michael Schroeter , and Andreas Lendlein
1.1
Historical Background
1.1.1
Biomedical Applications
Biomaterials are defi ned as any materials intended to interface with biological
systems to analyze, treat, or replace any tissue, organ, or function of the body [1].
The current trend in biomaterial development is shifted toward the use of biode-
gradable materials that have defi nite advantages in the fi elds of tissue engineering
[2] and drug delivery [3]. The general principle is to use a material that achieves a
specifi c therapeutic task and is subsequently, over time, degraded and removed
harmlessly from the body. As an increasingly relevant part of the medical device
and controlled release industry, biodegradable polymers are used to fabricate
temporary scaffolds for tissue regeneration, medical sutures, and nano- or micro-
scale drug delivery vehicles [4 - 6] .
The important properties that are required for biodegradable biomaterials can
be summarized as follows:
•
Nontoxic and endotoxin -free, aiming to minimalize unwanted foreign body
responses upon implantation.
•
Degradation time should be matched to the regeneration or required therapy
time.
•
Mechanical properties must be suited to the required task.
•
Degradation products should be nontoxic and readily cleared from the body.
•
Material must be easily processed to allow tailoring for the required task.
Although natural polymers such as collagen have been used in medical applica-
tions throughout history, synthetic polymers are valuable also, as they allow us to
tailor properties such as mechanical strength and erosion behavior. Naturally
