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Bioabsorbable Polymers: Processing Matters


If we had to use just one word to sum up the exceptional value of bioabsorbable polymers, it would be “change.”

Polylactic acid (PLA), Polyglycolide (PGA), Polycaprolactone (PCL) and their copolymers are unique in their ability change in the human body, and be absorbed without causing harm to living tissue — making them ideal materials for medical devices and implants. This quality allows the devices and implants made from bioabsorbable polymers to effect positive changes in patients’ bodies by speeding healing and delivering medicines. In this context, “change” is good.

But the changeability of bioabsorbable polymers can also create challenges. Because the performance of bioabsorbable polymers in medical devices and implants is, quite often, literally a life-and-death matter, it’s critical that device-makers be able to manage how the material (and their devices) change in the human body.

Bioabsorbable polymers are susceptible to temperature and moisture differences, a vulnerability that helps them dissolve inside a patient. However, temperature and moisture can also affect bioabsorbable polymers during manufacturing processes. These factors can influence the molecular weight, structure and morphology of the polymer, which in turn affects the mechanical properties of the material and the rate at which the polymer will dissolve in a patient’s body.

When that happens, the end result may be a polymer and/or a device that doesn’t behave as the manufacturer intended. A buildup of polymeric degradation products can also occur, possibly threatening a patient’s health.

Fortunately, testing of bioabsorbable polymers can go a long way toward ensuring the safety and efficacy of medical devices and implants made from these change-friendly materials. An array of testing methods can help us analyze bioabsorbable polymers, including:

  • Karl Fisher Titration — This bioabsorbable polymer testing method can help us determine moisture content and identify moisture contamination.
  • Gel Permeation Chromatography/Size Exclusion Chromatography (THF, Chloroform, HFIP) determines molecular weight of polymer samples.
  • Residual Monomer via Gas Chromatography (GC-FID) can help identify potential toxicity issues caused by the presence of residual monomers.
  • Degradation and aging studies can aid in understanding how long a bioabsorbable polymer may retain its integrity in patients’ bodies before beginning to degrade, and once degradation has begun how long it will take for the material to be partially and completely absorbed.
  • Through Nuclear Magnetic Resonance Spectroscopy Analysis, we can determine comonomer ratios.

Of course, there are many other tests that can help predict how a biodegradable polymer or a product made from one (or more) will behave in the real world. And since in the world of science “change” is often synonymous with “progress,” it seems likely researchers will continue to discover new ways to analyze biodegradable polymers — just as innovators will find new ways to use these change-friendly polymers to continue improving people’s health.