In vivo biocompatibility and biostability of modified polyurethanes

Mathur, Anshu B.; Collier, Terry O.; Kao, Weiyuan John; Wiggins, Michael J.; Schubert, Mark; Hiltner, A.; Anderson, James M.

doi:10.1002/(sici)1097-4636(199708)36:2<246::aid-jbm14>3.3.co;2-9

Cited by 52 publications

(77 citation statements)

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“…Poly(carbonate urethanes) are currently being examined as more biostable replacements for PEU in long‐term implants 1. Several in vitro and early in vivo studies demonstrated that polyurethanes with polycarbonate soft segments are more biostable than comparable poly(ether urethanes) 2–5. Evidence of surface degradation of poly(carbonate urethane) rods that were explanted from rabbits after 15 months in vivo have recently been reported 6.…”

Section: Introductionmentioning

confidence: 99%

Antioxidant inhibition of poly(carbonate urethane) in vivo biodegradation

Christenson

Anderson

Hiltner

2005

J Biomedical Materials Res

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This study compared the effect of an antioxidant on the in vivo biodegradation of a poly(carbonate urethane) (PCU) and a poly(ether urethane) (PEU). Unstrained PEU and PCU films with and without Santowhite were implanted subcutaneously into 3-month-old Sprague-Dawley rats for 3, 6, and 12 months. Characterization of unstabilized PEU and PCU with ATR-FTIR and SEM showed soft-segment and hard-segment degradation consistent with previous studies. In particular, evidence of chain scission and crosslinking of the surface was present in the ATR-FTIR spectra of explanted specimens. Addition of 2.2 wt % antioxidant inhibited the in vivo degradation of both PCU and PEU. Although the antioxidant probably improved polyurethane biostability by decreasing the susceptibility of the polymer to degradation, modulation of the cellular response to prevent the release of degradative agents was also possible. To differentiate the effects, the foreign-body response was investigated with the use of a standard cage implant protocol. Polyurethane films were implanted in wire mesh cages subcutaneously in rats for 4, 7, and 21 days. There were no statistical differences among materials in the inflammatory exudate cell counts, adherent cell densities, or percent fusion of macrophages into foreign-body giant cells (FBGCs). Therefore, it was concluded that the antioxidant inhibited degradation by capturing oxygen radicals that would otherwise cause polyurethane chain scission and crosslinking.

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Section: Introductionmentioning

confidence: 99%

Antioxidant inhibition of poly(carbonate urethane) in vivo biodegradation

Christenson

Anderson

Hiltner

2005

J Biomedical Materials Res

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“…[6,7] This can limit the suitability of these materials for long-term implants. It has been found, however, that the mechanical properties gradually deteriorate when the polyurethane devices are implanted.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Deformation of Polyurethanes

Laity

Taylor

Wong

et al. 2004

Journal of Macromolecular Science, Part B

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The mechanical properties of thermoplastic polyurethanes (TPU) depend upon their composition and the complex two-phase morphologies, which originate from microphase separation of chains segments. In the present work, poly(ether-urethanes) were prepared with hard segment contents from 36% to 71% by weight, by systematically varying the length of the soft-segment macrodiol. Samples were prepared by hot pressing or solvent casting, and the resulting hard-and soft-segment morphologies were characterized by using small-angle x-ray scattering (SAXS) and transmission electron microscopy (TEM). Environmental scanning electron microscopy (ESEM) was used to study the fracture surfaces of TPU samples. The deformation behavior of the morphology was studied in real time, by using 2-dimensional SAXS (2D-SAXS) at the Daresbury synchrotron radiation source. Two distinct mechanisms were identified, with the dominant mechanism in a given material 95 ORDER REPRINTS dependent on the copolymer composition and the extent of microphase separation, which developed during processing.

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“…The macrophage density on the hydrogels and Pellethane reached a maximum after 1 week and decreased gradually until 7 weeks, which was consistent with a previous report using polyurethane. 20 In contrast to macrophage density, the FBGC density on all polymer surfaces exhibited a minimum at 1 week, followed by a rapid increase up to 3 weeks, and then tended to reach a constant or slightly decreased value (Fig. 2).…”

Section: Cell Adhesionmentioning

confidence: 88%

“…It has been suggested that the polyethers are subject to oxidative degradation, which is initiated by abstraction of an ␣-methylene hydrogen atom attributed to hydroxyl radicals released from phagocytic cells. 15,16 This often resulted in decrease of average molecular weight, 8,47,48 generation of new bands observed by FTIR, 15,16,20,44 and alteration of polymer morphology. 16,23,25 Our previous results showed that the water capacity of hydrogels studied is larger than unity in PBS (pH 7.4) at 37°C, where water capacity was defined as the value of water weight in hydrogels divided by dried polymer weight.…”

Section: Discussionmentioning

confidence: 99%

“…Our results showed that minimal macrophage density and FBGC density on PEO 3.4k PDMS were influenced by PDMS, which might also play an important role in the retardation of degradation rate. Mathur et al 20 proposed that the reduction of the amount of total cell coverage and shielding effect of the PDMS on the surfaces could inhibit oxidative cleavage. Our previous study 17 found that a certain amount of PDMS domain in phase-separated hydrogel was exposed to the outermost layer, which allowed the surfaces to be PDMS-rich, even if the high flexibility and hydrophobicity of PDMS might have a high tendency to bury itself into the interior of hydrogel in an aqueous environment.…”

Section: Discussionmentioning

confidence: 99%

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Hydrogels based on poly(ethylene oxide) and poly(tetramethylene oxide) or poly(dimethyl siloxane). III. In vivo biocompatibility and biostability

Park

Bae

2002

J Biomedical Materials Res

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To investigate the effects of polymer chemistry and topology (linear or graft copolymer) on in vivo biocompatibility and biostability based on cage implant system, various hydrogels, composed of short hydrophilic [polyethylene oxide (PEO)] and hydrophobic block, were prepared by polycondensation reaction. Poly(tetramethylene oxide) (PTMO) or poly(dimethyl siloxane) (PDMS) was chosen as a hydrophobic block because of their wide utilization as a biomaterial. By using the specimens retrieved from rats killed after 1, 2, 3, 5, and 7 weeks' implantation, cellular and material responses were assessed. Most hydrogels showed a comparable value of macrophage density to Pellethane(R), control polymer, whereas they did significantly lower foreign body giant cell (FBGC) density and coverage because of the presence of PEO. However, PEO block length and polymer topology did not affect macrophage adhesion and FBGC formation in our polymer composition. The hydrogel based on PDMS alone showed significantly lower macrophage density and FBGC density than Pellethane(R), indicating that PDMS plays a role in inhibiting cellular adhesion. The results obtained from gel permeation chromatography curve and Fourier transform infrared spectra exhibited that all the polymers were susceptible to oxidative degradation in vivo. Although Pellethane(R) revealed surface degradation by 5 weeks in vivo, hydrogels showed rapid degradation in the bulk within 2 weeks because of the penetration of oxidative chemicals released from phagocytic cells into PEO domain of phase-separated hydrogels. The more significant degradation was observed in the hydrogels with longer PEO block and PTMO as a hydrophobic block instead of PDMS. It was evident that the minor degradation could be achieved by grafting PEO and adopting PDMS as a hydrophobic block in the hydrogel.

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In vivo biocompatibility and biostability of modified polyurethanes

Cited by 52 publications

References 0 publications

Antioxidant inhibition of poly(carbonate urethane) in vivo biodegradation

Antioxidant inhibition of poly(carbonate urethane) in vivo biodegradation

Mechanical Deformation of Polyurethanes

Hydrogels based on poly(ethylene oxide) and poly(tetramethylene oxide) or poly(dimethyl siloxane). III. In vivo biocompatibility and biostability

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