A case study
Abstract: Poly(lactic-co-glycolic) acid (PLGA) has attracted considerable interest as a base material for biomedical applications due to its: biocompatibility, tailored biodegradation rate, approval for clinical use in humans by the FDA and the potential to modify surface properties to provide better interaction with biological materials. Testing the end product should be done according to certain standards in-vitro, as well as to get a sense of these unique material’s behavior in simulated body conditions. This case study presents a serious of tests performed for one of Medibrane customers for their biodegradable surgical implant.
Author: Dr. Amir kraitzer
A customer is using a biodegradable implant in order to temporarily secure a wound at the healing period. The implant is required to hold mechanical properties for a minimum of 30 days and then to biodegrade gradually. ASTM 1635 deals with the testing of Hydrolytically Degradable Polymer Resins and Fabricated Forms for Surgical Implants. The customer requested to test the implant according to the standard.
Medibrane performed a degradation profile study so as to provide data regarding the strength retention, weight loss, and molecular weight (MW) of a biodegradable implant according to ASTM 1635-95-11. The study included an incubation of the final product (post sterilization) in purified water at 37oC for two months and extraction of samples at predefined time points, measuring strength retention using tensile machine, dry weight using analytical balance and MW using Gel Permeation chromatography (GPC).
Fig 1 presents the strength retention of the implant at different time points. As it can be seen, after 2 weeks the retention strength didn’t change significantly and after 2 months the maximal strength decreased by 20%.
The implants retained more than 80% of their initial strength after two months. The molecular weight was reduced by ~40% throughout the test period. The weight of the implants was kept relatively constant during the 2-month test period. During this time the slow reduction of the molecular weight and the absence of weight loss are evident that the degradation is stable and in accordance to bulk eroding poly-alpha hydroxy acids.