Particulate retrieval of hydrolytically degraded poly(lactide-co-glycolide) polymers

This article describes a technique for the retrieval of polymeric particula te debris following advanced hydrolytic in vitro degradation of a biodegrad able polymer and presents the results of the subsequent particle analysis. Granular 80/20 poly(L-lactide-co-glycolide) (PLG) was degraded in distilled , deionized water in Pyrex(TM) test tubes at 80 degrees C for 6 weeks. Subs equently, a density gradient was created by layering isopropanol over the w ater, followed by a 48-h incubation. Two opaque layers formed in the PLG tu bes, which were removed and filtered through 0.2-mu m polycarbonate membran e filters. In addition, Fourier transform IR spectroscopy (FTIR) was perfor med to confirm the presence of polymer in the removed layers. The filters w ere gold sputter coated, and scanning electron microscopy (SEM) images were made. FTIR analysis confirmed that the removed material was PLG. SEM image s of the extracts from the upper (lowest density) opaque layer showed a fin e, powder-like substance and globular structures of 500-750 nm. The SEM ima ges of the lower (highest density) opaque layer showed particles with a cry stalline-like morphology ranging in size from 4 to 30 mu m. Particulate PLG debris generated with the described technique can be useful for further st udies of its biological role in complications associated with poly(cr:hydro xy)ester implants. This study shows the presence of very persistent nano- a nd microparticles in the degradation pathway of PLG. (C) 2000 John Wiley & Sons, Inc.