PLA, PGA, and PLGA as biomaterials
- 1 Background
- 2 History
- 3 Synthesis
- 4 Bio-degradation Mechanism
- 5 Bulk Modification
- 6 Surface Modification
- 7 Biomedical Applications
- 8 Sources
The polymer materials of polylactic acid (PLA), polyglycolic acid (PGA), and poly(lactic-co-glycolic) acid (PLGA) have been shown in recent years to be strong contributors to the development of biodegradable medical implants within the human body, drug carrier designs, and even uses in the packaging industry. The immense utility of many of these polymers were over looked due to their degradation via hydrolysis. The increase in popularity can be attributed to a general increase in demand for biodegradable plastics (Xiao et al.). More focus on environmental responsibility as well as a push away from plastics produced from fossil fuel sources, create a high demand for plastics that are both biodegradable and able to be produced from organic sources (Cheng et al.) (Xiao et al. Fig 1).
There are three main areas of use for PLA, PGA, and PLGA plastics: (1) Use a drug carrier in drug delivery applications (2) The promotion of cell growth and organ healing in cell scaffolds and other tissue engineered materials (3) The implementation of plastics in packaging materials (Cheng et al.; Xiao et al.). It is also advantageous to utilize co-polymer and polymer blends of biodegradable monomers of PLA and PGA. PLGA is the most obvious example of Lactic Acid and Glycolic Acid co-polymerization. Some other common monomers that a co-polymerized with these monomers are malic acid or PEG (Cheng et al.). Some of the properties that can be modified through blending and co-polymerizing these polymers are biodegradability, hydrophilicity, mechanical properties, physical properties, and surface topography (Lee et al.; Sasatsu et al.).
1780 - Lactic Acid first discovered in 1780 by Carl Wilhelm Scheele (Experimental Chemist) (Auras et al.)
1880s - Industrial production of Lactic Acid in US (Auras et al.)
1944 - Study of Lactic Acid Condensation Polymers (Filachione et al.)
1954 - PGA became known (Gilding et al.)
1962 - PGA suture marketed as Dexon (Gilding et al.)
1994 - Kanebo LTd. introduced Lactron PLLA fiber adn spun-laid nonwovens (Auras et al.).
1996 - Mitsui Chemicals, Inc. commercialized PLA produced by polycondensation route (Auras et al.).
1997 - Formatin of Cargill Dow LLC, to commercialize PLA under the name NatureWorks (Auras et al.).
2003 - Toyota produced PLA for automotive applications (Auras et al.).
2005 - NatureWorksLLC and Teijin Limited formed 50-50 joint venture to market Ingeo bio-based thermoplastic resins (Auras et al.).
2008 - PURAC started to commercialize solid lactide monomers under PURALACT (Auras et al.).
2009 - PURAC, Sulzer, and Synbra announced production of PLA from solid lactide for foamed products (Auras et al.).
2010 - Recombinant Escherichia coli to produce PLA (Auras et al.).
The synthesis PLA, PGA, and PLGA can be done under many different mechanisms with main mechanisms being (1) Direct condensation polymerization (2) Ring Opening Polymerization each with its own set of advantages and disadvantages.
Polylactic Acid and Polyglycolic Acid
The extraction of the monomers is often not conducted by synthetic means unlike conventional plastics. Currently, most Lactic acid is produced through a fermentation process, over a synthetic method (Auras et al.).
Direct Condensation Polymerization
Ring Opening Polymerization
Alternative Polymerization Methods
Being aliphatic polyesters PLA, PGA, and PLGA are flexible and all degrade at certain pH range. This degradation is conducted via hydrolic cleavage of the bond between monomers (Auras et al.).
Rotary Cuff Surgery
Bone Fixation Components
Stress Shearing Effect
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