Biodegradation evaluation of polyether and polyester‐urethanes with oxidative and hydrolytic enzymes

Abstract

Enzyme-induced liberation of components from seven different radiolabeled polyurethanes was monitored by radiolabel counting of the incubation solutions and product isolation by high performance liquid chromatography (HPLC). The polyurethanes were selected to reflect variations in the hard-segment chemistry, soft-segment chemistry, and polyurethane hydrophilicity resulting from combinations of hydrophobic/hydrophilic soft segments. All materials were characterized using electron spectroscopy for chemical analysis, differential scanning calorimetry, size exclusion chromatography, and Fourier transform infrared spectroscopy. The material surfaces were examined both before and after incubation with enzyme and control solutions using scanning electron microscopy. Biodegradation assays were carried out at 37 degrees C using cholesterol esterase (CE) and horseradish peroxidase (HRP) under optimal pH conditions for each enzyme. The hydrolytic enzyme (CE) was effective in releasing degradation products that contained hard-segment components from some of the polyurethanes. HPLC analysis of products for a polyesterurethane synthesized with toluene diisocyanate (TDI) suggested that the bulk of the incorporated radiolabeled TDI was still covalently bonded within the cleaved chain segments of the original polymer and was not released as pure toluene diamine (TDA). The data suggest that urethane linkages in the soft-segment domains of phase separated polyetherurea-urethanes may be more prone to cleavage by CE than are the urea/urethane groups in the hard-segment domains. This could be related to the nature of the hard-segment domain structures. The oxidative enzyme (HRP) was not able to induce liberation of radiolabeled segments from either the polyether or polyester-based polyurethanes.

Palliative treatment of malignant gastroduodenal obstruction with metallic stent: prospective comparison of covered and uncovered stents

“…The covering membrane can be damaged by mechanical trauma during the process of stent deployment or chemical degradation with exposure to digestive juice [23]. Chemical degradation of polyurethane after exposure to strongly acidic juice and pancreatic secretion has been reported in several studies [24,25]. Materials such as polyurethane and silicone have been used to cover the surface of stents [10Á13]; nevertheless, new chemical-resistant covering materials are necessary to prevent disruption of the covering membrane.…”

Use of surface-modifying macromolecules to enhance the biostability of segmented polyurethanes

“…Further complicating material development is the fact that there is still a general lack of understanding of the specific biological interactions involved in the process of biodegradation. 12 At the same time, the use of these new polyurethanes is still under question for their thrombogenic nature, and although there have been some approaches developed to improve polymer-blood compatibility, [13][14][15][16][17] no method has been proven successful for challenging applications such as heart valves and small-diameter arteries.…”

Characterization of the Polyurethanolytic Activity of Two Alicycliphilus sp. Strains Able To Degrade Polyurethane and N -Methylpyrrolidone

“…However, only Comamonas acidovorans TB-35 has the ability to attack solid PU and use it as a carbon source (31). Protease, urease, and esterase activities have been associated with the degradation of polyester PU by fungi and bacteria (12,18,31,32,34,39). Polyurethanase protease activities have been reported for Pseudomonas fluorescens and P. chlororaphis (19,36), polyurethanase lipase activity has been detected in Bacillus subtilis strains (35), and polyurethanase esterase activities have been reported for Corynebacterium sp., Comamonas acidovorans TB-35, and P. chlororaphis (20,22,30).…”