Biomaterials Tutorial

Poly(lactic acid) (PLA) and Poly(glycolic acid) (PGA)

Felix Simonovsky
University of Washington Engineered Biomaterials

Poly(lactic acid) (PLA), poly(glycolic acid) (PGA), and their copolymers are linear aliphatic polyesters derived from glycolic acid and lactic acid monomers. 

They are the most widely used biodegradable polymers.  The presence of ester linkages in the polymer backbone allows gradual hydrolytic degradation of the polymer.  The degradation products are endogenous compounds and as such are non-toxic. 

In order to balance the material properties of these polymers for a wider range of possible applications, copolymers of PGA and PLA are used.  PGA is more hydrophilic, while PLA is more hydrophobic.  While PGA is highly crystalline, crystallinity is lost rapidly in the PGA/PLA copolymers.   Adjustments in material properties lead to changes in the rates of hydration (swelling) and hydrolysis (degradation), making the material suitable for specific applications.

These materials are popular because they have already been used in many approved medical implant devices and have been shown to be safe, non-toxic, and biocompatible.  These polymers have been used in the development of several commercially available medical products, such as sutures, tissue screws and tacks, guided tissue regeneration membranes for dentistry, internal bone fixation devices, microspheres for implantable drug delivery systems, and systems for meniscus and cartilage repair.

These polymers can potentially be used in the design of vascular and urological stents and skin substitutes.  That is possible through the manipulation of the polymer characteristics of these materials, such as their three dimensional architecture, their mechanical and structural integrity, and their biodegradability.  They can also be used as scaffolds for tissue engineering and for tissue reconstruction.

References:

Ratner BD, Hoffman AS, Schoen FJ, Lemons JE, Editors. Biomaterials science: An introduction to materials in medicine, 2nd ed. London: Elsevier Academic Press; 2004.

Wnek GE, Bowlin GL, Editors. Encyclopedia of biomaterials and biomedical engineering. New York: Marcel Dekker; 2004.