Characterization and assessment of a novel poly(ethylene oxide)/polyurethane composite hydrogel (Aquavene®) as a ureteral stent biomaterial

• Published in: Journal of biomedical materials research 1998-03, Vol.39 (4), p.642-649
• Main Authors: Gorman, S. P., Tunney, M. M., Keane, P. F., Van Bladel, K., Bley, B.
• Format: Article
• Language: English
• Subjects: Aquavene; Biocompatible Materials; Biological and medical sciences; Body fluids; Elastic moduli; encrustation; Extraction; Flow of fluids; Gels; Hardness; Hydration; hydrogel; Hydrogels; Materials Testing; Medical sciences; Microscopy, Atomic Force; Microscopy, Electron, Scanning; Molecular structure; Polyethylene oxides; polyurethane; Polyurethanes; silicone; Silicones; Stents; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the urinary system; Ureter; ureteral stent
• ISSN: 0021-9304; 1097-4636
• DOI: 10.1002/(SICI)1097-4636(19980315)39:4<642::AID-JBM20>3.0.CO;2-7

The effective long‐term use of indwelling ureteral stents is often hindered by the formation of encrusting deposits which may cause obstruction and blockage of the stent. Development of improved ureteral stent biomaterials capable of preventing or reducing encrustation is therefore particularly desirable. In this study, the suitability as a ureteral stent biomaterial of Aquavene®, a novel poly(ethylene oxide)/polyurethane composite hydrogel was compared with that of silicone and polyurethane, two materials widely employed in ureteral stent manufacture. Examination of Aquavene® in dry and hydrated states by confocal laser scanning microscopy, scanning electron microscopy, and atomic force microscopy showed the presence of numerous channels within a cellular matrix structure. The channel size increased considerably to as much as 10 μm in diameter in the hydrated state. Aquavene® provided superior resistance to encrustation and intraluminal blockage over a 24‐week period in a simulated urine flow model. Unobstructed urine flow continued with Aquavene® at 24 weeks, whereas silicone and polyurethane stents became blocked with encrustation at 8 and 10 weeks, respectively. Weight loss within Aquavene® on the order of 9% (w/w) over the 24–week flow period indicates that extraction of the noncrosslinked poly(ethylene oxide) hydrogel may be responsible for the prevention of encrustation blockage of this biomaterial. In the dry state, Aquavene® was significantly harder than either silicone or polyurethane, as shown by Young's modulus, and rapidly became soft on hydration. These additional properties of Aquavene® would facilitate ease of stent insertion in the dry state past obstructions in the ureter and provide improved patient comfort on subsequent biomaterial hydration in situ. Aquavene® is a promising candidate for use in the urinary tract, as it is probable that effective long‐term urine drainage would be maintained in vivo. Further evaluation of this novel biomaterial is therefore warranted. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 642–649, 1998.